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1
Schröder, Tilman Raphael, Hans-Josef Dohmen, Dieter Brillert, and Friedrich-Karl Benra. "Impact of Leakage Inlet Swirl Angle in a Rotor–Stator Cavity on Flow Pattern, Radial Pressure Distribution and Frictional Torque in a Wide Circumferential Reynolds Number Range." International Journal of Turbomachinery, Propulsion and Power 5, no. 2 (April 17, 2020): 7. http://dx.doi.org/10.3390/ijtpp5020007.
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In the side-chambers of radial turbomachinery, which are rotor–stator cavities, complex flow patterns develop that contribute substantially to axial thrust on the shaft and frictional torque on the rotor. Moreover, leakage flow through the side-chambers may occur in both centripetal and centrifugal directions which significantly influences rotor–stator cavity flow and has to be carefully taken into account in the design process: precise correlations quantifying the effects of rotor–stator cavity flow are needed to design reliable, highly efficient turbomachines. This paper presents an experimental investigation of centripetal leakage flow with and without pre-swirl in rotor–stator cavities through combining the experimental results of two test rigs: a hydraulic test rig covering the Reynolds number range of 4 × 10 5 ≤ R e ≤ 3 × 10 6 and a test rig for gaseous rotor–stator cavity flow operating at 2 × 10 7 ≤ R e ≤ 2 × 10 8 . This covers the operating ranges of hydraulic and thermal turbomachinery. In rotor–stator cavities, the Reynolds number R e is defined as R e = Ω b 2 ν with angular rotor velocity Ω , rotor outer radius b and kinematic viscosity ν . The influence of circumferential Reynolds number, axial gap width and centripetal through-flow on the radial pressure distribution, axial thrust and frictional torque is presented, with the through-flow being characterised by its mass flow rate and swirl angle at the inlet. The results present a comprehensive insight into the flow in rotor–stator cavities with superposed centripetal through-flow and provide an extended database to aid the turbomachinery design process.
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Denton, J. D., and L. Xu. "The exploitation of three-dimensional flow in turbomachinery design." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 213, no. 2 (February 1, 1998): 125–37. http://dx.doi.org/10.1243/0954406991522220.
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Many of the phenomena involved in turbomachinery flow can be understood and predicted on a two-dimensional (2D) or quasi-three-dimensional (Q3D) basis, but some aspects of the flow must be considered as fully three-dimensional (3D) and cannot be understood or predicted by the Q3D approach. Probably the best known of these fully 3D effects is secondary flow, which can only be predicted by a fully 3D calculation which includes the vorticity at inlet to the blade row. It has long been recognized that blade sweep and lean also produce fully 3D effects and approximate methods of calculating these have been developed. However, the advent of fully 3D flow field calculation methods has made predictions of these complex effects much more readily available and accurate so that they are now being exploited in design. This paper will attempt to describe and discuss fully 3D flow effects with particular reference to their use to improve turbomachine performance. Although the discussion is restricted to axial flow machines, many of the phenomena discussed are equally applicable to mixed and radial flow turbines and compressors.
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Перевезенцев, Виктор, Viktor Perevezentsev, Максим Шилин, and Maksim Shilin. "Improving the design of the seal gaps in the flow of the pumping unit GTK-10-4." Bulletin of Bryansk state technical university 2015, no. 1 (March 31, 2015): 35–40. http://dx.doi.org/10.12737/22746.
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Describes the methods of modernization seal the radial clearance of the gas turbine by using the honeycomb structure at the periphery of the wheel. Discusses the gas-dynamic and thermal engineering problems using honeycomb seals in turbomachinery.
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Fei, Cheng-Wei, Wen-Zhong Tang, Guang-chen Bai, and Zhi-Ying Chen. "A dynamic probabilistic design method for blade-tip radial running clearance of aeroengine high-pressure turbine." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 10 (August 28, 2014): 1861–72. http://dx.doi.org/10.1177/0954406214549267.
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Around the engineering background of the probabilistic design of high-pressure turbine (HPT) blade-tip radial running clearance (BTRRC) which conduces to the high-performance and high-reliability of aeroengine, a distributed collaborative extremum response surface method (DCERSM) was proposed for the dynamic probabilistic analysis of turbomachinery. On the basis of investigating extremum response surface method (ERSM), the mathematical model of DCERSM was established. The DCERSM was applied to the dynamic probabilistic analysis of BTRRC. The results show that the blade-tip radial static clearance δ = 1.82 mm is advisable synthetically considering the reliability and efficiency of gas turbine. As revealed by the comparison of three methods (DCERSM, ERSM, and Monte Carlo method), the DCERSM reshapes the possibility of the probabilistic analysis for turbomachinery and improves the computational efficiency while preserving computational accuracy. The DCERSM offers a useful insight for BTRRC dynamic probabilistic analysis and optimization. The present study enrichs mechanical reliability analysis and design theory.
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Jahn, Ingo, and Peter Jacobs. "Using Meridional Streamline and Passage Shapes to Generate Radial Turbomachinery Geometry and Meshes." Applied Mechanics and Materials 846 (July 2016): 1–6. http://dx.doi.org/10.4028/www.scientific.net/amm.846.1.
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An important aspect for structural and aerodynamics design of radial flow turbomachinery is the definition of the geometry and the generation of meshes for computational analysis. Particularly in the area of computational design and optimization, the way the geometry is defined is important, as it can limit design space. Traditionally, radial compressors and radial turbine rotors are defined using a mechanical design approach. Effectively a hub and shroud profile, followed by a rotorblade geometry are defined and the shape is adjusted in order to meet certain aerodynamic boundary conditions. The current paper presents an alternative approach, in which the overall geometry is defined starting from an aerodynamic requirement. The corresponding rotor and blade geometry is generated automatically, based on certain constraints. The advantage of this approach is the ability to define directly the aerodynamic requirements, which may allow a simpler efficient optimization of the aerodynamics.
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Siddappaji, Kiran, and Mark G. Turner. "Versatile Tool for Parametric Smooth Turbomachinery Blades." Aerospace 9, no. 9 (August 31, 2022): 489. http://dx.doi.org/10.3390/aerospace9090489.
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Designing blades for efficient energy transfer by turning the flow and angular momentum change is both an art and iterative multidisciplinary engineering process. A robust parametric design tool with few inputs to create 3D blades for turbomachinery and rotating or non-rotating energy converters is described in this paper. The parameters include axial–radial coordinates of the leading/trailing edges, construction lines (streamlines), metal angles, thickness-to-chord ratio, standard, and user-defined airfoil type among others. Using these, 2D airfoils are created, conformally mapped to 3D stream surfaces, stacked radially with multiple options, and they are transformed to a 3D Cartesian coordinate system. Smooth changes in blade curvature are essential to ensure a smooth pressure distribution and attached flow. B-splines are used to control meanline curvature, thickness, leading edge shape, sweep-lean, and other parameters chordwise and spanwise, making the design iteration quick and easy. C2 curve continuity is achieved through parametric segments of cubic and quartic B-splines and is better than G2. New geometries using an efficient parametric scheme and minimal CAD interaction create watertight solid bodies and optional fluid domains. Several examples of ducted axial and radial turbomachinery with special airfoil shapes or otherwise, unducted rotors including propellers and wind and hydrokinetic turbines are presented to demonstrate versatility and robustness of the tool and can be easily tied to any automation chain and optimizer.
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Kirk, R. G. "Evaluation of AMB Turbomachinery Auxiliary Bearings." Journal of Vibration and Acoustics 121, no. 2 (April 1, 1999): 156–61. http://dx.doi.org/10.1115/1.2893958.
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The use of active magnetic bearings (AMB) for turbomachinery has experienced substantial growth during the past two decades. The advantages for many applications make AMB’s a very attractive solution for potentially low loss and efficient support for both radial and thrust loads. New machinery must be shop tested prior to shipment to the field for installation on-line. For AMB turbomachinery, one additional test is the operation of the auxiliary drop or overload bearings. A major concern is ability of the selected auxiliary bearing to withstand the contact forces following an at speed rotor drop. The proper design of AMB machinery requires the calculation of the anticipated loading for the auxiliary bearings. Analytical techniques to predict the rotor transient response are reviewed. Results of transient response evaluation of a full-size compressor rotor are presented to illustrate some of the important parameters in the design for rotor drop.
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Schröder, Tilman, Sebastian Schuster, and Dieter Brillert. "Experimental Investigation of Centrifugal Flow in Rotor–Stator Cavities at High Reynolds Numbers >108." International Journal of Turbomachinery, Propulsion and Power 6, no. 2 (May 26, 2021): 13. http://dx.doi.org/10.3390/ijtpp6020013.
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The designers of radial turbomachinery need detailed information on the impact of the side chamber flow on axial thrust and torque. A previous paper investigated centripetal flow through narrow rotor–stator cavities and compared axial thrust, rotor torque and radial pressure distribution to the case without through-flow. Consequently, this paper extends the investigated range to centrifugal through-flow as it may occur in the hub side chamber of radial turbomachinery. The chosen operating conditions are representative of high-pressure centrifugal compressors used in, for example, carbon capture and storage applications as well as hydrogen compression. To date, only the Reynolds number range up to Re=2·107 has been investigated for centrifugal through-flow. This paper extends the range to Reynolds numbers of Re=2·108 and reports results of experimental and numerical investigations. It focuses on the radial pressure distribution in the rotor–stator cavity and shows the influence of the Reynolds number, cavity width and centrifugal mass flow rate. It therefore extends the range of available valid data that can be used to design radial turbomachinery. Additionally, this analysis compares the results to data and models from scientific literature, showing that in the higher Reynolds number range, a new correlation is required. Finally, the analysis of velocity profiles and wall shear delineates the switch from purely radial outflow in the cavity to outflow on the rotor and inflow on the stator at high Reynolds numbers in comparison to the results reported by others for Reynolds numbers up to Re=2·107.
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Salah, Salma I., Mahmoud A. Khader, Martin T. White, and Abdulnaser I. Sayma. "Mean-Line Design of a Supercritical CO2 Micro Axial Turbine." Applied Sciences 10, no. 15 (July 23, 2020): 5069. http://dx.doi.org/10.3390/app10155069.
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Supercritical carbon dioxide (sCO2) power cycles are promising candidates for concentrated-solar power and waste-heat recovery applications, having advantages of compact turbomachinery and high cycle efficiencies at heat-source temperature in the range of 400 to 800 ∘C. However, for distributed-scale systems (0.1–1.0 MW) the choice of turbomachinery type is unclear. Radial turbines are known to be an effective machine for micro-scale applications. Alternatively, feasible single-stage axial turbine designs could be achieved allowing for better heat transfer control and improved bearing life. Thus, the aim of this study is to investigate the design of a single-stage 100 kW sCO2 axial turbine through the identification of optimal turbine design parameters from both mechanical and aerodynamic performance perspectives. For this purpose, a preliminary design tool has been developed and refined by accounting for passage losses using loss models that are widely used for the design of turbomachinery operating with fluids such as air or steam. The designs were assessed for a turbine that runs at inlet conditions of 923 K, 170 bar, expansion ratio of 3 and shaft speeds of 150k, 200k and 250k RPM respectively. It was found that feasible single-stage designs could be achieved if the turbine is designed with a high loading coefficient and low flow coefficient. Moreover, a turbine with the lowest degree of reaction, over a specified range from 0 to 0.5, was found to achieve the highest efficiency and highest inlet rotor angles.
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Yang, Y. L., C. S. Tan, and W. R. Hawthorne. "Aerodynamic Design of Turbomachinery Blading in Three-Dimensional Flow: An Application to Radial Inflow Turbines." Journal of Turbomachinery 115, no. 3 (July 1, 1993): 602–13. http://dx.doi.org/10.1115/1.2929297.
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A computational method based on a theory for turbomachinery blading design in three-dimensional inviscid flow is applied to a parametric design study of a radial inflow turbine wheel. As the method requires the specification of swirl distribution, a technique for its smooth generation within the blade region is proposed. Excellent agreements have been obtained between the computed results from this design method and those from direct Euler computations, demonstrating the correspondence and consistency between the two. The computed results indicate the sensitivity of the pressure distribution to a lean in the stacking axis and a minor alteration in the hub/shroud profiles. Analysis based on a Navier–Stokes solver shows no breakdown of flow within the designed blade passage and agreement with that from a design calculation; thus the flow in the designed turbine rotor closely approximates that of an inviscid one. These calculations illustrate the use of a design method coupled to an analysis tool for establishing guidelines and criteria for designing turbomachinery blading.
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Persky, Rodney, and Emilie Sauret. "Loss models for on and off-design performance of radial inflow turbomachinery." Applied Thermal Engineering 150 (March 2019): 1066–77. http://dx.doi.org/10.1016/j.applthermaleng.2019.01.042.
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Ghaly, W. S. "A Parametric Study of Radial Turbomachinery Blade Design in Three-Dimensional Subsonic Flow." Journal of Turbomachinery 112, no. 3 (July 1, 1990): 338–45. http://dx.doi.org/10.1115/1.2927665.
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An aerodynamic design method is described and used to implement a parametric study of radial turbomachinery blade design in three-dimensional subsonic flow. Given the impeller hub and shroud, the number of blades and their stacking position, the design method gives the detailed blade shape, flow, and pressure fields that would produce a prescribed tangentially averaged swirl schedule. The results from that study show that decreasing the number of blades increases the blade wrap, and that the blade loading is strongly affected by the rate of change of mean swirl along the mean streamlines. The results also show that the blade shape and the pressure field are rather sensitive to the prescribed mean swirl schedule, which suggests that, by carefully tailoring the swirl schedule, one might be able to control the blade shape and the pressure field and hence secondary flow.
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Zangeneh, M. "A compressible three-dimensional design method for radial and mixed flow turbomachinery blades." International Journal for Numerical Methods in Fluids 13, no. 5 (September 5, 1991): 599–624. http://dx.doi.org/10.1002/fld.1650130505.
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Liu, Gao-Lian. "The Radial Equilibrium Problem of Flow in Wave Machinery." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 207, no. 1 (February 1993): 23–30. http://dx.doi.org/10.1243/pime_proc_1993_207_004_02.
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The present paper deals with the radial equilibrium problem of gas flow at the inlet and outlet of a wave rotor theoretically, presenting a method of solution. The salient feature of this method is that, in contrast to turbomachinery, the outlet flow parameters are related to those at inlet by the state characteristic (compatibility) equations of unsteady rotor flow. The numerical example has shown that the radial equilibrium effect plays a very important role in the design and performance of wave machinery and hence it is suggested that a complete gas dynamic design procedure of a wave machine should include two parts: (a) solution of the one-dimensional unsteady relative flow in rotor at the mean radius; (b) solution of the radial equilibrium problem of gas flow at the rotor inlet and outlet.
15
Jennions, I. K., and P. Stow. "The Importance of Circumferential Non-uniformities in a Passage-Averaged Quasi-Three-Dimensional Turbomachinery Design System." Journal of Engineering for Gas Turbines and Power 108, no. 2 (April 1, 1986): 240–45. http://dx.doi.org/10.1115/1.3239894.
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The purpose of this paper is to show, for both rotating and non-rotating blade rows, the importance of including circumferential non-uniform flow effects in a quasi-three-dimensional blade design system. The paper follows from previous publications on the system in which the mathematical analysis and computerized system are detailed. Results are presented for a different stack of the nozzle guide vane presented previously and for a turbine rotor. In the former case it is again found that the blade force represents a major contribution to the radial pressure gradient, while for the rotor the radial pressure gradient is dominated by centrifugal effects. In both examples the effects of circumferential non-uniformities are detailed and discussed.
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Abed, Cheikh Brahim, Sofiane Khelladi, Michael Deligant, Abdellatif El Marjani, Moisés Solis, and Farid Bakir. "Experimental Validation of the Aerodynamic Performance of an Innovative Counter-Rotating Centrifugal Compressor." Energies 14, no. 9 (April 30, 2021): 2582. http://dx.doi.org/10.3390/en14092582.
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Turbomachinery with double counter-rotating impellers offers more degrees of freedom in the choice of design and control parameters compared to conventional machines. For these innovative machines, the literature review shows that more publications concerning axial type turbomachines are available than centrifugal ones. This work deals with a design and experimental performance analysis, applied to two counter-rotating impellers of a centrifugal compressor “CRCC”. CRCC was designed with a specifically developed tool based on mean-line approach coupled with optimization algorithms and a stream-curvature through-flow method to satisfy the design criteria. This paper presents an experimental validation of the CRCC design tool and its performances against the baseline “SR”, composed of one centrifugal impeller and a volute for which experimental data are available. CRCC numeric simulations are also validated by experimental data. For a fair comparison between CRCC and SR, the same volute is used for both configurations. The CRCC studied here includes a first conventional impeller with an axial inlet and a radial outlet, while the second impeller is parametrically designed and can be considered a rotating bladed diffuser with a radial inlet and outlet. The obtained results show that CRCC can deliver a pressure rise increase of two compared to SR, along with an increase of isentropic efficiency and also validate the design method of this novel layout. The experimental results also show that the speed ratio of CRCC has a positive effect on the surge and shock margin.
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Jennions, I. K., and P. Stow. "A Quasi-Three-Dimensional Turbomachinery Blade Design System: Part I—Throughflow Analysis." Journal of Engineering for Gas Turbines and Power 107, no. 2 (April 1, 1985): 301–7. http://dx.doi.org/10.1115/1.3239715.
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The purpose of this work has been to develop a quasi-three-dimensional blade design and analysis system incorporating fully linked throughflow, blade-to-blade and blade section stacking programs. In Part I of the paper, the throughflow analysis is developed. This is based on a rigorous passage averaging technique to derive throughflow equations valid inside a blade row. The advantages of this approach are that the meridional streamsurface does not have to be of a prescribed shape, and by introducing density weighted averages the continuity equation is of an exact form. Included in the equations are the effects of blade blockage, blade forces, blade-to-blade variations and loss. The solution of the equations is developed for the well-known streamline curvature method, and the contributions from these extra effects on the radial equilibrium equation are discussed. Part II of the paper incorporates the analysis into a quasi-three-dimensional computing system and demonstrates its operational feasibility.
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Siddappaji, Kiran, and Mark G. Turner. "An Advanced Multifidelity Multidisciplinary Design Analysis Optimization Toolkit for General Turbomachinery." Processes 10, no. 9 (September 13, 2022): 1845. http://dx.doi.org/10.3390/pr10091845.
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The MDAO framework has become an essential part of almost all fields, apart from mechanical, transportation, and aerospace industries, for efficient energy conversion or otherwise. It enables rapid iterative interaction among several engineering disciplines at various fidelities using automation tools for design improvement. An advanced framework from low to high fidelity is developed for ducted and unducted turbomachinery blade designs. The parametric blade geometry tool is a key feature which converts low-fidelity results into 3D blade shapes and can readily be used in high-fidelity multidisciplinary simulations as part of an optimization cycle. The geometry generator and physics solvers are connected to DAKOTA, an open-source optimizer with parallel computation capability. The entire cycle is automated and new design iterations are generated with input parameter variations controlled by DAKOTA. Single- and multi-objective genetic algorithm and gradient method-based optimization cases are demonstrated for various applications. B-splines are used to define smooth perturbation of parametric variables chordwise and spanwise of the blade. The ability to create parametric 3D blade shapes quickly from low-fidelity analyses with advanced control is demonstrated to be unique and enables a rapid 3D design cycle. Non-intuitive designs are feasible in this framework and designers can really benefit from parametric geometry manipulation. Optimization at each fidelity is realized through automation. As part of the multidisciplinary analysis, 3D structural analysis is also performed using the unidirectional fluid–structure interaction for a few cases with imported pressure loads from the 3D RANS solution. Examples of axial turbofans, compressor rotors, turbines, radial compressors, propellers, wind and hydrokinetic turbines are demonstrated to prove generality.
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Moore, J. J., and M. B. Flathers. "Aerodynamically Induced Radial Forces in a Centrifugal Gas Compressor: Part 1—Experimental Measurement." Journal of Engineering for Gas Turbines and Power 120, no. 2 (April 1, 1998): 383–90. http://dx.doi.org/10.1115/1.2818134.
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Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing techniquesis employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increase with higher pressures and speeds. The results are nondimensionalized, allowing the radial loading for different operating conditions to be predicted.
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Schobeiri, M. T., J. L. Gilarranz, and E. S. Johansen. "Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points." International Journal of Rotating Machinery 10, no. 1 (2004): 33–44. http://dx.doi.org/10.1155/s1023621x04000041.
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This article deals with the aerodynamic and performance behavior of a three-stage high pressure research turbine with 3-D curved blades at its design and off-design operating points. The research turbine configuration incorporates six rows beginning with a stator row. Interstage aerodynamic measurements were performed at three stations, namely downstream of the first rotor row, the second stator row, and the second rotor row. Interstage radial and circumferential traversing presented a detailed flow picture of the middle stage. Performance measurements were carried out within a rotational speed range of 75% to 116% of the design speed. The experimental investigations have been carried out on the recently established multi-stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory,TPFL, of Texas A&M University.
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Wadia, A. R., and B. F. Beacher. "Three-Dimensional Relief in Turbomachinery Blading." Journal of Turbomachinery 112, no. 4 (October 1, 1990): 587–96. http://dx.doi.org/10.1115/1.2927697.
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The leading edge region of turbomachinery blading in the vicinity of the endwalls is typically characterized by an abrupt increase in the inlet flow angle and a reduction in total pressure associated with endwall boundary layer flow. Conventional two-dimensional cascade analysis of the airfoil sections at the endwalls indicates large leading edge loadings, which are apparently detrimental to the performance. However, experimental data exist that suggest that cascade leading edge loading conditions are not nearly as severe as those indicated by a two-dimensional cascade analysis. This discrepancy between two-dimensional cascade analyses and experimental measurements has generally been attributed to inviscid three-dimensional effects. This article reports on two and three-dimensional calculations of the flow within two axial-flow compressor stators operating near their design points. The computational results of the three-dimensional analysis reveal a significant three-dimensional relief near the casing endwall that is absent in the two-dimensional calculations. The calculated inviscid three-dimensional relief at the endwall is substantiated by airfoil surface static pressure measurements on low-speed research compressor blading designed to model the flow in the high-speed compressor. A strong spanwise flow toward the endwall along the leading edge on the suction surface of the airfoil is responsible for the relief in the leading edge loading at the endwall. This radial migration of flow results in a more uniform spanwise loading compared to that predicted by two-dimensional calculations.
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Holaind, Norman, Giuseppe Bianchi, Maxence De Miol, Samira Sayad Saravi, Savvas A. Tassou, Arthur Leroux, and Hussam Jouhara. "Design of radial turbomachinery for supercritical CO 2 systems using theoretical and numerical CFD methodologies." Energy Procedia 123 (September 2017): 313–20. http://dx.doi.org/10.1016/j.egypro.2017.07.256.
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Laos, Hector E., John M. Vance, and Steven E. Buchanan. "Hybrid Brush Pocket Damper Seals for Turbomachinery." Journal of Engineering for Gas Turbines and Power 122, no. 2 (January 3, 2000): 330–36. http://dx.doi.org/10.1115/1.483211.
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Pocket damper seals perform a dual function: both sealing the pressurized gas around a rotating shaft and providing large amounts of vibration damping. The annular cavity between the labyrinth seal teeth is subdivided into separate annular cavities around the circumference of the rotor by partitioning walls. Also, the upstream and downstream teeth have different radial clearances to the rotor. These seals have been shown to provide a remarkable amount of direct damping to attenuate vibration in turbomachinery, but they generally leak more than conventional labyrinth seals if both seals have the same minimum clearance. Conversely, brush seals allow less than half the leakage of labyrinth seals, but published test results show no significant amount of damping. They are considered to be a primary choice for the seals in new aircraft engine designs because of their low leakage. This paper will describe a recently invented hybrid brush/pocket damper seal that combines high damping with low leakage. Previous brush seal results were studied and calculations were made to select a brush seal to combine with the pocket damper design. The result is a hybrid seal with high damping and low leakage. A special design feature can also allow active vibration control as a bonus benefit. A computer code written for the original pocket damper seal was modified to include the brush element at the exit blade. Results from the computer code indicate that the hybrid seal can have less leakage than a six bladed (or 6 knives) labyrinth seal along with orders of magnitude more damping. Experimental evaluations of the damping and leakage performance of the hybrid seal are being conducted by the authors. The experimental work reported here tested the damping capability of the new hybrid brush seal by exciting the seal journal through an impedance head. A conventional six-bladed labyrinth seal of the same working dimensions was also tested. The brush hybrid pocket damper seal is found to leak less than the labyrinth seal while producing two to three times more damping than the original pocket damper seal (orders of magnitude more than the conventional labyrinth). [S0742-4795(00)01102-9]
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Zangeneh, M., A. Goto, and H. Harada. "On the role of three-dimensional inverse design methods in turbomachinery shape optimization." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 213, no. 1 (January 1, 1999): 27–42. http://dx.doi.org/10.1243/0954406991522167.
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The application of a three-dimensional (3D) inverse design method in which the blade geometry is computed for a specified distribution of circulation to the design of turbomachinery blades is explored by using two examples. In the first instance the method is applied to the design of radial and mixed flow impellers to suppress secondary flows. Based on our understanding of the fluid dynamics of the flow in the impeller, simple guidelines are developed for input specification of the inverse method in order to systematically design impellers with suppressed secondary flows and a more uniform exit flow field. In the second example the method is applied to the design of a vaned diffuser. Again based on the understanding of the detailed flow field in the diffuser obtained by using 3D viscous calculations and oil flow visualizations, simple design guidelines are developed for input specification to the inverse method in order to suppress corner separation. In both cases the guidelines are verified numerically and in the case of the diffuser further experimental validation is presented.
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Borges, J. E. "A Three-Dimensional Inverse Method for Turbomachinery: Part II—Experimental Verification." Journal of Turbomachinery 112, no. 3 (July 1, 1990): 355–61. http://dx.doi.org/10.1115/1.2927667.
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The performance of an impeller of a low-speed radial-inflow turbine, designed using a three-dimensional inverse technique, was evaluated experimentally. This performance was compared with that achieved by a rotor typical of the present technology. Besides measuring overall quantities, in special efficiency, some traverses of flow velocity were carried out. The results of the tests showed that the new design had a peak total-to-static efficiency 1.4 points better than the conventional build. The traverses indicated that the level of swirl at exhaust of the new impeller was only half as big as that for the conventional rotor, in spite of the fact that both impellers were designed to have zero swirl at outlet. It is also shown that the rotor loss for the new impeller is considerably lower than for the conventional wheel. This research points to the desirability of using a three-dimensional inverse method for the design of turbomachines with significant three-dimensional flows.
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Borges, J. E. "A Three-Dimensional Inverse Method for Turbomachinery: Part I—Theory." Journal of Turbomachinery 112, no. 3 (July 1, 1990): 346–54. http://dx.doi.org/10.1115/1.2927666.
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There are surprisingly few inverse methods described in the literature that are truly three dimensional. Here, one such method is presented. This technique uses as input a prescribed distribution of the mean swirl, i.e., radius times mean tangential velocity, given throughout the meridional section of the machine. In the present implementation the flow is considered inviscid and incompressible and is assumed irrotational at the inlet to the blade row. In order to evaluate the velocity field inside the turbomachine, the blades (supposed infinitely thin) are replaced by sheets of vorticity, whose strength is related to the specified mean swirl. Some advice on the choice of a suitable mean swirl distribution is given. In order to assess the usefulness of the present procedure, it was decided to apply it to the design of an impeller for a low-speed radial-inflow turbine. The results of the tests are described in the second part of this paper.
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Joslyn, H. D., and R. P. Dring. "Axial Compressor Stator Aerodynamics." Journal of Engineering for Gas Turbines and Power 107, no. 2 (April 1, 1985): 485–92. http://dx.doi.org/10.1115/1.3239754.
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Axisymmetric, through-flow calculations, currently the “backbone” of most multistage turbomachinery design systems, are being pushed to their limit. This is due to the difference between the complex, three-dimensional flows that actually occur in turbomachinery and the two-dimensional flow assumed in this type of analysis. To foster the development of design analyses that account more accurately for these three-dimensional effects, there is a need for detailed flow field data in a multistage environment. This paper presents a survey of the initial results from a detailed experimental study of the aerodynamics of the second stage of a large scale, two-stage axial compressor. Data were acquired over a range of flow coefficients. The data presented here are for the second stator and include airfoil and endwall flow visualization, and radial-circumferential traverse measurements presented in the form of fullspan contour plots of total pressure. Also presented are the spanwise distributions of total and static pressures, axial velocity, air angles, and blockage. The effect of increased loading on the growth of the hub corner stall and its impact on these parameters is discussed.
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Tanaka, Keizo, Anestis I. Kalfas, and Howard P. Hodson. "Development of single sensor fast response pressure probes." E3S Web of Conferences 345 (2022): 01004. http://dx.doi.org/10.1051/e3sconf/202234501004.
Full textAbstract:
Multi-sensor fast response pressure probes are often used in turbomachinery investigations. However, the size of multi-sensor probes are often larger than is ideal. This paper describes the development of a single sensor pressure probe that has sufficient sensitivity for the measurements of unsteady 3D flow fields in turbomachines. Because there is only one sensor, the probe can be made much smaller than previous designs. Several types of probe were designed and tested using largescale models in a wind tunnel. Both the steady state and the dynamic response have been investigated. The relationship between the shape of the probe and its yaw and pitch sensitivity has been investigated through measurements of the pressure distribution on the large-scale models and through visualizations of the flow. Dambach and Hodson [3] proposed a new method of data reduction for a single sensor pressure probe. In that work, a single sensor pressure probe with the shape of a triangular prism was fabricated and tested with success in a radial flow turbine where the flow field was mainly 2D. The probe was shown to have only yaw sensitivity while pitch sensitivity is also important in the survey of three dimensional turbomachinery flows. In this paper, the model probes were used to assess the pitch sensitivity of single sensor pressure probes. All the probes have the sensing face at the end of a radially mounted stem so that they can be used for inter bladerow measurements. Through the steady state measurements, the dependency of pitch sensitivity on (1) the shape of the probe stem (e.g., Square, Circular, and Triangular) and (2) the angle of the slanted sensing face at the tip of the probe were investigated. Having assessed all the designs based on the steady state experiments, the dynamic behaviour of selected designs was investigated. The results indicate that a slanted face and appropriate probe tip design can be used to increase the pitch sensitivity of the single sensor probe to acceptable levels.
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Racca, Alberto, Tom Verstraete, and Lorenzo Casalino. "Radial Turbine Thermo-Mechanical Stress Optimization by Multidisciplinary Discrete Adjoint Method." International Journal of Turbomachinery, Propulsion and Power 5, no. 4 (November 25, 2020): 30. http://dx.doi.org/10.3390/ijtpp5040030.
Full textAbstract:
This paper addresses the problem of the design optimization of turbomachinery components under thermo-mechanical constraints, with focus on a radial turbine impeller for turbocharger applications. Typically, turbine components operate at high temperatures and are exposed to important thermal gradients, leading to thermal stresses. Dealing with such structural requirements necessitates the optimization algorithms to operate a coupling between fluid and structural solvers that is computationally intensive. To reduce the cost during the optimization, a novel multiphysics gradient-based approach is developed in this work, integrating a Conjugate Heat Transfer procedure by means of a partitioned coupling technique. The discrete adjoint framework allows for the efficient computation of the gradients of the thermo-mechanical constraint with respect to a large number of design variables. The contribution of the thermal strains to the sensitivities of the cost function extends the multidisciplinary outlook of the optimization and the accuracy of its predictions, with the aim of reducing the empirical safety factors applied to the design process. Finally, a turbine impeller is analyzed in a demanding operative condition and the gradient information results in a perturbation of the grid coordinates, reducing the stresses at the rotor back-plate, as a demonstration of the suitability of the presented method.
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Zhao, Haifang, and Robert J. Stango. "Effect of Flow-Induced Radial Load on Brush Seal/Rotor Contact Mechanics." Journal of Tribology 126, no. 1 (January 1, 2004): 208–15. http://dx.doi.org/10.1115/1.1609492.
Full textAbstract:
Brush seals comprised of special-alloy wire bristles are currently being used in lieu of traditional labyrinth seals for turbomachinery applications. This advancement in seal technology utilizes close-packed bristles that readily undergo lateral deformation arising from aerodynamic loads as well as loads imparted by the rotor surface. Thus, during operation, filament tips remain in contact with the rotor surface, which, in turn, inhibits leakage between successive stages of the turbine, and increases engine efficiency. However, contact forces generated at the interface of the rotor and fiber tips can lead to eventual bristle fatigue and wear of the seal/rotor system. Therefore, it is important that reliable modeling techniques be developed that can help identify complex relationships among brush seal design parameters, in-service loads, and contact forces that arise during the operation of turbomachinery. This paper is concerned with modeling and evaluating bristle deformation, bending stress, and bristle/rotor contact forces that are generated at the interface of the fiber and rotor surface due to radial fluid flow, and augments previous work reported by the author’s, which assessed filament tip forces that arise solely due to interference between the bristle/rotor. The current problem derives its importance from aerodynamic forces that are termed “blow-down,” that is, the inward radial flow of gas in close proximity to the face of the seal. Thus, bristle deformation, bristle tip reaction force, and bristle bending stress is computed on the basis of an in-plane, large-displacement mechanics analysis of a cantilever beam that is subjected to a uniform radial load. Solutions to the problem are obtained for which the filament tip is constrained to lie on the rotor surface, and includes the effect of Coulombic friction at the interface of the fiber tip and rotor. Contact forces are obtained for a range of brush seal design parameters including fiber lay angle, flexural rigidity, and length. In addition, the governing equation is cast in non-dimensional form, which extends the range of applicability of solutions to brush seals having a more general geometry and material composition.
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Tjokroaminata, W. D., C. S. Tan, and W. R. Hawthorne. "A Design Study of Radial Inflow Turbines With Splitter Blades in Three-Dimensional Flow." Journal of Turbomachinery 118, no. 2 (April 1, 1996): 353–61. http://dx.doi.org/10.1115/1.2836650.
Full textAbstract:
An inverse design technique to design turbomachinery blading with splitter blades in three-dimensional flow is developed. It is based on the use of Clebsch transformation, which allows the velocity field to be written as a potential part and a rotational part. It is shown that the rotational part can be expressed in terms of the mean swirl schedule (the circumferential average of the product of radius and tangential velocity) and the blade geometry that includes the main blade as well as the splitter blade. This results in an inverse design approach, in which both the main and the splitter blade geometry are determined from a specification of the swirl schedule. Previous design study of a heavily loaded radial inflow turbine, without splitter blades, for a rather wide variety of specified mean swirl schedules results in a blade shape with unacceptable nonradial blade filament; the resulting reduced static pressure distribution yields an “inviscid reverse flow region” covering almost the first half of the blade pressure surface. When the inverse design technique is applied to the design study of the turbine wheel with splitter blades, the results indicate that the use of splitter blades is an effective means for making the blade filament at an axial location more radial as well as a potential means for eliminating any “inviscid reverse flow” region that may exist on the pressure side of the blades.
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Northall, John D. "The Influence of Variable Gas Properties on Turbomachinery Computational Fluid Dynamics." Journal of Turbomachinery 128, no. 4 (February 1, 2005): 632–38. http://dx.doi.org/10.1115/1.2221324.
Full textAbstract:
This paper describes the inclusion of variable gas properties within a Reynolds average Navier-Stokes solver for turbomachinery and its application to multistage turbines. Most current turbomachinery computational fluid dynamics (CFD) models the gas as perfect with constant specific heats. However, the specific heat at constant pressure CP can vary significantly. This is most marked in the turbine where large variations of temperature are combined with variations in the fuel air ratio. In the current model CP is computed as a function of the local temperature and fuel air ratio using polynomial curve fits to represent the real gas behavior. The importance of variable gas properties is assessed by analyzing a multistage turbine typical of the core stages of a modern aeroengine. This calculation includes large temperature variations due to radial profiles at inlet, the addition of cooling air, and work extraction through the machine. The calculation also includes local variations in fuel air ratio resulting from the inlet profile and the dilution of the mixture by the addition of coolant air. A range of gas models is evaluated. The addition of variable gas properties is shown to have no significant effect on the convergence of the algorithm, and the extra computational costs are modest. The models are compared with emphasis on the parameters of importance in turbine design, such as capacity, work, and efficiency. Overall the effect on turbine performance prediction of including variable gas properties in three-dimensional CFD is found to be small.
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Visser, F. C., J. J. H. Brouwers, and R. Badie. "Theoretical analysis of inertially irrotational and solenoidal flow in two-dimensional radial-flow pump and turbine impellers with equiangular blades." Journal of Fluid Mechanics 269 (June 25, 1994): 107–41. http://dx.doi.org/10.1017/s0022112094001503.
Full textAbstract:
Using the theory of functions of a complex variable, in particular the method of conformal mapping, the irrotational and solenoidal flow in two-dimensional radialflow pump and turbine impellers fitted with equiangular blades is analysed. Exact solutions are given for the fluid velocity along straight radial pump and turbine impeller blades, while for logarithmic spiral pump impeller blades solutions are given which hold asymptotically as (r1/r2)n→0, in whichr1is impeller inner radius,r2is impeller outer radius andnis the number of blades. Both solutions are given in terms of a Fourier series, with the Fourier coefficients being given by the (Gauss) hypergeometric function and the beta function respectively. The solutions are used to derive analytical expressions for a number of parameters which are important for practical design of radial turbomachinery, and which reflect the two-dimensional nature of the flow field. Parameters include rotational slip of the flow leaving radial impellers, conditions to avoid reverse flow between impeller blades, and conditions for shockless flow at impeller entry, with the number of blades and blade curvature as variables. Furthermore, analytical extensions to classical one-dimensional Eulerian-based expressions for developed head of pumps and delivered work of turbines are given.
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Shutin, Denis, Leonid Savin, and Alexander Babin. "A Review on Active Bearings and Perspectives of Using Them in Rotating Machinery." Applied Mechanics and Materials 630 (September 2014): 181–87. http://dx.doi.org/10.4028/www.scientific.net/amm.630.181.
Full textAbstract:
The paper examines the issues of improving the rotor units by means of using support units with actively changeable characteristics. An overview of the known solutions related to the use of active bearings in various types of turbomachinery is provided. A closer look is given at the design and features of active radial bearings, the main elements of which are fluid film bearings. The results of mathematical modeling of active hybrid bearings are presented. The prospects of the use of this type of supports to improve the dynamic characteristics of rotating machinery, including reducing vibrations caused by various factors, are analyzed. Promising directions of development of active bearings are considered, which primarily involves the modification of system components and rotor motion control system algorithms, including intelligent technologies and artificial intelligence methods.
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Alawadhi, Khaled, Yousef Alhouli, Ali Ashour, and Abdullah Alfalah. "Design and Optimization of a Radial Turbine to Be Used in a Rankine Cycle Operating with an OTEC System." Journal of Marine Science and Engineering 8, no. 11 (October 29, 2020): 855. http://dx.doi.org/10.3390/jmse8110855.
Full textAbstract:
Design and optimization of a radial turbine for a Rankine cycle were accomplished ensuring higher thermal efficiency of the system despite the low turbine inlet temperature. A turbine design code (TDC) based on the meanline design methodology was developed to construct the base design of the turbine rotor. Best design practices for the base design were discussed and adopted to initiate a robust optimization procedure. The baseline design was optimized using the response surface methodology and by coupling it with the genetic algorithm. The design variables considered for the study are rotational speed, total to static speed ratio, hub radius ratio, shroud radius ration, and number of blades. Various designs of the turbine were constructed based on the Central Composite Design (CCD) while performance variables were computed using the in-house turbine design code (TDC) in the MATLAB environment. The TDC can access the properties of the working fluid through a subroutine that links NIST’s REFPROP to the design code through a subroutine. The finalization of the geometry was made through an iterative process between 3D-Reynolds-Averaged Navier-Stokes (RANS) simulations and the one-dimensional optimization procedure. 3D RANS simulations were also conducted to analyze the optimized geometry of the turbine rotor for off-design conditions. For computational fluid dynamics (CFD) simulation, a commercial code ANSYS-CFX was employed. 3D geometry was constructed using ASYS Bladegen while structured mesh was generated using ANSYS Turbogrid. Fluid properties were supplied to the CFD solver through a real gas property (RGP) file that was constructed in MATLAB by linking it to REFPROP. Computed results show that an initial good design can reduce the time and computational efforts necessary to reach an optimal design successfully. Furthermore, it can be inferred from the CFD calculation that Response Surface Methodology (RSM) employing CFD as a model evaluation tool can be highly effective for the design and optimization of turbomachinery.
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Wang, Yuqi, Jinxing Li, Di Zhang, and Yonghui Xie. "Numerical Investigation on Aerodynamic Performance of SCO2 and Air Radial-Inflow Turbines with Different Solidity Structures." Applied Sciences 10, no. 6 (March 19, 2020): 2087. http://dx.doi.org/10.3390/app10062087.
Full textAbstract:
Supercritical carbon dioxide (SCO2) is of great use in miniature power systems. It obtains the characteristics of high density and low viscosity, which makes it possible to build a compact structure for turbomachinery. For a turbine design, an important issue is to figure out the appropriate solidity of the rotor. The objective of this research is to present the aerodynamic performance and provide the design reference for SCO2 and air radial-inflow turbines considering different solidity structures. For the low solidity case of SCO2 turbine, new splitter structures are proposed to improve its performance. The automatic design and simulation process are established by batch modes in MATLAB. The numerical investigation is based on a 3D viscous compressible N-S equation and the actual fluid property of SCO2 and air. The distributions of flow parameters are first presented. Rotor blade load and aerodynamic force are then thoroughly analyzed and the aerodynamic performances of all cases are obtained. The SCO2 turbine has larger power capacity and higher efficiency while the performance of the air turbine is less affected by rotor solidity. For both SCO2 and air, small solidity can cause the unsatisfactory flow condition at the inlet and the shroud section of the rotor, while large solidity results in the aerodynamic loss at the trailing edge of rotor blade and the hub of rotor outlet. A suction side offset splitter can greatly improve the performance of the low solidity SCO2 turbine.
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Xu, Kunbo, Yun Shi, Weiyang Qiao, and Zhirong Wang. "The Methodological and Experimental Research on the Identification and Localization of Turbomachinery Rotating Sound Source." Energies 15, no. 22 (November 17, 2022): 8647. http://dx.doi.org/10.3390/en15228647.
Full textAbstract:
The localization and quantification of turbomachinery rotating sound sources is an important challenge in the field of aeroacoustics. In order to compensate the motion of a rotating sound source, a rotating beamforming technique is developed and applied in a flow duct, which uses a wall-mounted microphone array placed circularly parallel to the fan, to detect the broadband noise source of the aeroengine fan. A simulation of three discrete rotating sound sources with a non-constant rotational speed is pursued to verify the effectiveness in reconstruction of the correct source positions and quantitative prediction of the source amplitudes. The technique is ulteriorly experimentally implemented at an axial low-speed fan test rig facility. The fan test rig has 19 rotor blades and 18 stator vanes, with a design speed up to 3000 rpm. The method can accurately identify the radial and circumferential positions of the three rotating sound sources in the simulation case, large side-lobes appear near the main-lobe of the sound source due to the geometric influence of the microphone array. A noticeable feature of beamforming images for axial flow fan is that the sound sources appear to be concentrated in the tip region rather than distributed along the span.
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Cravero, Carlo, and Davide Marsano. "A comparison of strategies to extend the operating range of radial compressors for turbocharging." E3S Web of Conferences 414 (2023): 02011. http://dx.doi.org/10.1051/e3sconf/202341402011.
Full textAbstract:
The operating range extension of radial compressors is a crucial aspect in turbocharging the internal combustion engines in order to extend the operating range of the system at high efficiency for fuel and environmental impact reduction. The future scenario of automotive propulsion will have the fuel cells at the top of the ranking of possible reference systems in substitution of thermal reciprocating engines. Proton exchange membrane fuel cells for automotive or aerospace vehicles are frequently turbocharged because compressed air for the fuel cell stack is required in the cathode system. Therefore, like in turbocharged internal combustion engines, a radial compressor is combined and connected with a radial turbine to exploit the thermal energy of the exhaust gas from the fuel cell. The study and the development of this sort of radial turbomachinery is still strategic to guarantee high performance of the overall propulsion system. The operating range is an important issue and current turbocharger design must be adapted to the new requirements of the fuel cells systems with a need for extending it. Various techniques to extend the operating range of the centrifugal compressor have been investigated and a summary is reported in this work, with a focus on the casing treatment. Through a CFD simulation campaign with appropriate simplified models, the effects of installing the ported shroud, the shutter or the axial groove have been calculated with respect to a baseline configuration. These simulations have supported the identification of the main limits and advantages for each of these solutions at different operating regimes. The performance maps and some physical parameters of interest have been compared.
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Wang, Jian, Suping Wen, Wenbo Wang, and Guang Xi. "Intelligence design method for three-dimensional vaned diffusers in a centrifugal compressor." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 6 (January 8, 2018): 674–90. http://dx.doi.org/10.1177/0957650917750713.
Full textAbstract:
This paper presents a multi-objective optimization-based intelligence design method for the design of the three-dimensional vaned diffuser for a given centrifugal compressor. This design method consists of three-dimensional vaned diffuser design model and its solving strategy. The three-dimensional vaned diffuser design model consists of the diffuser geometry mathematical model, performance evaluation model, objective equation, and design space. The diffuser geometry is described by the mathematical model of the meridional configurations and vane camber, trailing edge lean, and thickness. The generic design space is determined through literature statistical investigation. An NSGA-II multi-objective optimization algorithm, utilized to solve the three-dimensional vaned diffuser design model, directs the diffuser geometry variables to achieve the maximum stage isentropic efficiency and static pressure ratio at the design point within the design space automatically and intelligently. The presented three-dimensional vaned diffuser design method is demonstrated using a case test for a centrifugal impeller. The convergence of evolutionary solving for this three-dimensional vaned diffuser model is analyzed in detail, which provides the convergence reference for engineering applications. Three representative three-dimensional vaned diffusers on Pareto front are utilized to check the diversity of geometry shape and overall range performance characteristics. The results show that the three-dimensional vaned diffuser design method established here has excellent potential in automated design and maximizing stage performance. The method reported here could provide a valuable reference for the intelligent design of radial turbomachinery diffusers.
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Zaidi, Sohail H., and Robin L. Elder. "Flow Studies using Laser Anemometry Technique in a Small Power Unit Radial Inflow Turbine." International Journal of Rotating Machinery 3, no. 2 (1997): 107–15. http://dx.doi.org/10.1155/s1023621x97000110.
Full textAbstract:
T-100 is a multipurpose small power unit developed by Sundstrand Power Systems (USA). An extensive research programme was launched for the detailed tests of the rig components including inlet protection system, Compressor stage, Combustor and the Turbine stage. Turbomachinery Group at Cranfield was involved in the study of the Turbine unit used in this programme. From the design point of view, detailed aerodynamics in these small units are of great interest especially where high velocities and narrow passages are involved. Experimental study was carried out to investigate the flow in the region between the nozzle guide vanes and the turbine rotor entry. The main concern was to find out how the nozzle guide vane flow was modified by the rotor and how the rotor flow was affected by the nozzle guide vanes. Laser measurements were taken at these positions for various flow conditions. An other area which needs considerable attention is downstream of the turbine rotor where the turning of flow and mixing process make the situation very complicated. Laser studies were undertaken in that region and to gain more confidence on laser results, a Cobra pressure probe was traversed at these stations. This paper describes various steps undertaken to obtain laser results within the machine. At the end typical laser results have been presented and discussed.
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Lazarovski, Nikolay, Paskal Novakov, and Anastas Yangyozov. "Mass Transfer Modeling into Disk Spaces of Heat Turbomachines." Defect and Diffusion Forum 362 (April 2015): 1–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.362.1.
Full textAbstract:
The thermal aerodynamic analysis of the processes in thermal turbomachinery is of great importance when it comes their design and operation in order to achieve reliable and trouble-free operation in the required turbo-power range. The distribution of kinematic and thermodynamic parameters of the working medium around heavy loaded working disks and labyrinth seals has a significant influence on heat-mass exchange and energy transformation processes. Object of this work is thermo-aerodynamic research of mass exchange processes associated with the movement of the working medium in typical complex clearances between the rotor and stator of the steam turbines of disk type and determining axial forces in the rotor. Results based on one-dimensional and two-dimensional formulations of the problem are analyzed and compared with the results of field experiment of turbine P12-90 / 18, which before the reconstruction had problems with unstable axial loading during operation in wide power range. After proper reconstruction the turbine is in a sustainable balance throughout the whole range of operation modes. There is consistency in the results in quantitative and qualitative terms regarding the extreme conditions of axial loading. There is a three-dimensional approach to solving the problem of distribution of axial loading on the structural elements of the rotor, whose advantage is the obtaining of a detailed picture of the passing fluid in the clearances between the rotor and stator of the aggregate and diaphragm-disk spaces, and a detailed presentation of the uneven distribution of the axial forces on the front surfaces. The applied thermal aerodynamic approach allows to predict the main characteristics of steam turbines at different axial and radial clearances, changing during the operation in case of wear of the the crest of the labyrinth seals. This approach can serve as a thermo-aerodynamic diagnosis of the condition of the flow part of different thermal turbomachinery and in variable working modes.
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Schüler, Eckhard, and Olaf Berner. "Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves." Lubricants 9, no. 2 (February 10, 2021): 18. http://dx.doi.org/10.3390/lubricants9020018.
Full textAbstract:
In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.
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Cuturi, Nicolò, and Enrico Sciubba. "Design of a Tandem Compressor for the Electrically-Driven Turbocharger of a Hybrid City Car." Proceedings 58, no. 1 (September 12, 2020): 24. http://dx.doi.org/10.3390/wef-06934.
Full textAbstract:
Within a broader national project aimed at the hybridization of a standard city car (the 998 cc Mitsubishi-derived gasoline engine of the Smart W451), our team tackled the problem of improving the supercharger performance and response. The design concept is that of eliminating the mechanical connection between the compressor and the turbine. It turned out that it is also possible to modify both components to extract extra power from the engine and to use it to recharge the battery pack. First, the initial configuration was analyzed on the basis of the design data provided by the manufacturer. Then, a preliminary performance assessment of the turbocharged engine allowed us to identify three “typical” operating points that could be used to properly redesign the turbomachinery. It was decided to maintain the radial configuration for both turbine and compressor, but to redesign the latter by adding an inducer. For the turbine, only minor modifications to the NGV and rotor blades shape were deemed necessary. Fully 3-D CFD simulations of the rotating machines were performed to assess their performance at three operating points: the kick-in point of the original turbo (2000 rpm), the maximum power regime (5500 rpm) and an intermediate point (3500 rpm) close to the minimum specific fuel consumption (SFC) for the original engine. The results presented in this paper demonstrate that the efficiency of the compressor is noticeably improved for steady operation at all three operating points, and that its choking characteristics have been improved, while its surge line has not been appreciably affected. The net energy recovery was also calculated, and demonstrated interesting returns in terms of storable energy in the battery pack.
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Nikolaev, Vitaly S., Sergey A. Abalakin, and Igor V. Tishchenko. "Comparison of efficiency losses due to leaks for turbine units of aviation air conditioning systems with petal-type gas-dynamic bearings and ball bearings." Refrigeration Technology 111, no. 1 (September 7, 2022): 13–20. http://dx.doi.org/10.17816/rf96964.
Full textAbstract:
BACKGROUND: Designers of turbomachines strive to increase the efficiency of expanding compressed gases by reducing all kinds of energy losses, particularly due to clearances between the impeller and the body elements of the turbomachine.
AIM: This article aimed to evaluate a possible increase in efficiency with a decrease in the radial and axial clearance between the blades of a radial-axial impeller and the casing of a centrifugal expander in the designs of turbomachines with ball bearings and petal-type gas-dynamic bearings.
MATERIALS AND METHODS: The radial and axial clearances between the blades of the radial-axial impeller and the centrifugal expander casing in the designs of turbomachines with ball bearings and petal-type gas-dynamic bearings were compared by analyzing the experience of Russian and international experts in developing turbomachines. Models were presented for estimating the efficiency losses of a centrifugal expander depending on the value of the radial and axial clearances. A comparative calculation of the efficiency loss for medium- and high-cooling-capacity refrigeration turbines of aircraft air conditioning systems was performed.
RESULTS: Based on the calculations, a conclusion was derived about the predominance of the influence of the radial clearance. The calculations revealed that with a decrease in the clearances between the impeller and the casing in a design with petal-type bearings, a refrigeration turbine of medium cooling capacity (16 kW, 2 impellers) can be expected to experience an increase in efficiency by an average of 2.3%; this expected increase is 0.75% to 1.4% for a high-capacity refrigeration turbine (55 kW, 3 or 4 impellers). Findings indicate that performing works to reduce radial clearances in the designs of turbomachines with petal-type gas-dynamic bearings is necessary.
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Cuturi, Nicolò, and Enrico Sciubba. "Design of a Tandem Compressor for the Electrically-Driven Turbocharger of a Hybrid City Car." Energies 14, no. 10 (May 17, 2021): 2890. http://dx.doi.org/10.3390/en14102890.
Full textAbstract:
Within a broader national project aimed at the hybridization of a standard city car (the 998 cc Mitsubishi-derived gasoline engine of the Smart W451), our team tackled the problem of improving the supercharger performance and response. The originally conceived design innovation was that of eliminating the mechanical connection between the compressor and the turbine. In the course of the study, it turned out that it is also possible to modify both components to extract extra power from the engine and to use it to recharge the battery pack. This required a redesign of both compressor and turbine. First, the initial configuration was analyzed on the basis of the design data provided by the manufacturer. Then, a preliminary performance assessment of the turbocharged engine allowed us to identify three “typical” operating points that could be used to properly redesign the turbomachinery. It was decided to maintain the radial configuration for both turbine and compressor, but to redesign the latter by adding an inducer. For the turbine, only minor modifications to the nozzle guide vanes (NGV) and rotor blades shape were deemed necessary, while a more substantial modification was in order for the compressor. Fully 3-D computational fluid dynamics simulations of the rotating machines were performed to assess their performance at three operating points: the kick-in point of the original turbo (2000 rpm), the maximum power regime (5500 rpm), and an intermediate point (3500 rpm) close to the minimum specific fuel consumption for the original engine. The results presented in this paper demonstrate that the efficiency of the compressor is noticeably improved for steady operation at all three operating points, and that its choking characteristics have been improved, while its surge line has not been appreciably affected. The net energy recovery was also calculated and demonstrated interesting returns in terms of storable energy in the battery pack.
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Magrini, Andrea. "Body Force Model Implementation of Transonic Rotor for Fan/Airframe Simulations." Aerospace 9, no. 11 (November 18, 2022): 725. http://dx.doi.org/10.3390/aerospace9110725.
Full textAbstract:
Three-dimensional throughflow models represent a turbomachinery cascade via a force distribution without the need for detailed geometric modelling in the numerical solution, saving consistent computational resources. In this paper, we present the application of a body force method on an axial transonic fan implemented into an in-house tool for axisymmetric throughflow simulations. By a systematic comparison of local and integral quantities with a validated numerical solution, the capabilities and limitations of the model are discussed for different operating regimes. The implementation is first validated at the peak efficiency calibration point, providing a good duplication of blade flow variables and radial profiles. The design total pressure is matched with a 0.6% absolute difference and a slightly higher slope of the characteristic towards the stall. The isentropic efficiency curve is penalised after the choking mass flow rate calibration, presenting an absolute difference close to 2%, although with a consistent off-design trend. In general, the model provides a satisfactory representation of the flow field and the outflow spanwise distributions, with locally larger discrepancies near the endwalls. Finally, the method is applied to simulate the fan and outlet guide vanes installed into an isolated turbofan nacelle. The onset of intake stall at a high angle of attack is compared between the body force and a boundary conditions-based approaches, highlighting the importance of adopting fully coupled solution methods to study fan/airframe interaction problems.
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Wen, Suping, Jian Wang, Ting Li, and Guang Xi. "Reducing solid particle erosion of an axial fan with sweep and lean using multidisciplinary design optimization." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 14 (February 7, 2014): 2584–603. http://dx.doi.org/10.1177/0954406214521409.
Full textAbstract:
A multidisciplinary design optimization (MDO) system is established to reduce solid particle erosion of an axial induced draft fan with sweep and lean. The method improves the erosion resistance of the fan blade in the aerodynamic design stage through a change of blade sweep and lean. The multidisciplinary design optimization approach takes the place of the traditional time-consuming design method by automatic calculation of the flow field, stress distribution, dynamic frequencies, and erosion distribution for blade, controlled by an optimization strategy. A multi-objective particle swarm optimization (MOPSO) algorithm combined with radial basis function approximation model is employed for finding a compromise between the conflicting demands of high efficiency and low average erosion rate with constraints on the pressure ratio and structural responses for the blade. The Navier–Stokes solver, finite element method (FEM) is used to predict the aerodynamic performance and mechanical performance of the blade, respectively. Particle paths in a viscous flow are calculated using the Lagrangian method and Tabakoff rebound model. And then Tabakoff erosion model is used to predict erosion of the blade surface. Several representative designs are selected along the Pareto front to verify using computer aided engineering tools. A compromise solution is used to analyze in detail. Compared with the reference design, the optimal design increases the η/ η0 slightly by 0.53%, while decreases the ɛavg / ɛavg0 markedly by 13.7%. The result shows that the optimized blade favors a reduced total pressure due to its forward sweep. The decrease of the ɛavg/ ɛavg0 is attributed to a reduced impact velocity and impact angle. The analysis of variance technique indicates that the blade lean has a direct impact on performances with respect to efficiency, erosion, and von Mises stress of the blade, and the blade sweep law near hub has an immeasurable influence on blade von Mises stress. As a conclusion, it can be drawn that the proposed approach may open a new opportunity for the design of axial fan to reduce erosion damage of blade taking other disciplines into consideration. Meanwhile, the multidisciplinary design optimization system can be extended to other turbomachinery and erosion-resistant design fields.
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Pagès, Valdo, Pierre Duquesne, Stéphane Aubert, Laurent Blanc, Pascal Ferrand, Xavier Ottavy, and Christoph Brandstetter. "UHBR Open-Test-Case Fan ECL5/CATANA." International Journal of Turbomachinery, Propulsion and Power 7, no. 2 (May 31, 2022): 17. http://dx.doi.org/10.3390/ijtpp7020017.
Full textAbstract:
The application of composite fans enables disruptive design possibilities but increases sensitivity to multi-physical resonance between aerodynamic, structure dynamic and acoustic phenomena. As a result, aeroelastic problems increasingly set the stability limit. Test cases of representative geometries without industrial restrictions are a key element of an open scientific culture but are currently non-existent in the turbomachinery community. In order to provide a multi-physical validation benchmark representative of near-future UHBR fan concepts, the open-test-case fan stage ECL5 was developed at Ecole Centrale de Lyon. The design intention was to develop a geometry with high efficiency and a wide stability range that can be realized using carbon fibre composites. This publication aims to introduce the final test case, which is currently fabricated and will be experimentally tested. The fan blades are composed of a laminate made of unidirectional carbon fibres and epoxy composite plies. Their structural properties and the ply orientations are presented. To characterize the test case, details are given on the aerodynamic design of the whole stage, structure dynamics of the fan and aeroelastic stability of the fan. These are obtained with a state-of-art industrial design process: static and modal FEM, RANS and LRANS simulations. Aerodynamic analysis focuses on performance and shows critical flow structures such as tip leakage flow, radial flow migration and flow separations. Mechanical modes of the fan are described and discussed in the context of aeroelastic interactions. Their frequency distribution is validated in terms of resonance risk with respect to synchronous vibration. The aeroelastic stability of the fan is evaluated at representative operating points with a systematic approach. Potential instabilities are observed far from the operating line and do not compromise experimental campaigns.
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Fischer, Axel, Walter Riess, and Joerg R. Seume. "Performance of Strongly Bowed Stators in a Four-Stage High-Speed Compressor." Journal of Turbomachinery 126, no. 3 (July 1, 2004): 333–38. http://dx.doi.org/10.1115/1.1649743.
Full textAbstract:
The FVV sponsored project “Bow Blading” (cf. acknowledgments) at the Turbomachinery Laboratory of the University of Hannover addresses the effect of strongly bowed stator vanes on the flow field in a four-stage high-speed axial compressor with controlled diffusion airfoil (CDA) blading. The compressor is equipped with more strongly bowed vanes than have previously been reported in the literature. The performance map of the present compressor is being investigated experimentally and numerically. The results show that the pressure ratio and the efficiency at the design point and at the choke limit are reduced by the increase in friction losses on the surface of the bowed vanes, whose surface area is greater than that of the reference (CDA) vanes. The mass flow at the choke limit decreases for the same reason. Because of the change in the radial distribution of axial velocity, pressure rise shifts from stage 3 to stage 4 between the choke limit and maximum pressure ratio. Beyond the point of maximum pressure ratio, this effect is not distinguishable from the reduction of separation by the bow of the vanes. Experimental results show that in cases of high aerodynamic loading, i.e., between maximum pressure ratio and the stall limit, separation is reduced in the bowed stator vanes so that the stagnation pressure ratio and efficiency are increased by the change to bowed stators. It is shown that the reduction of separation with bowed vanes leads to a increase of static pressure rise towards lower mass flow so that the present bow bladed compressor achieves higher static pressure ratios at the stall limit.
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Raheel, Muhammad M., and Abraham Engeda. "Systematic Design Approach for Radial Blade Regenerative Turbomachines." Journal of Propulsion and Power 21, no. 5 (September 2005): 884–92. http://dx.doi.org/10.2514/1.1426.
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