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Biba, Yuri, i Peter Menegay. "Inverse Design of Centrifugal Compressor Stages Using a Meanline Approach". International Journal of Rotating Machinery 10, nr 1 (1.01.2004): 75–84. http://dx.doi.org/10.1080/10236210490258106.
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Biba, Yuri, i Peter Menegay. "Inverse Design of Centrifugal Compressor Stages Using a Meanline Approach". International Journal of Rotating Machinery 10, nr 1 (2004): 75–84. http://dx.doi.org/10.1155/s1023621x04000089.
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This article discusses an approach for determining meanline geometric parameters of centrifugal compressor stages given specified performance requirements. This is commonly known as the inverse design approach. The opposite process, that of calculating performance parameters based on geometry input is usually called analysis, or direct calculation. An algorithm and computer code implementing the inverse approach is described. As an alternative to commercially available inverse design codes, this tool is intended for exclusive OEM use and calls a trusted database of loss models for individual stage components, such as impellers, guide vanes, diffusers, etc. The algorithm extends applicability of the inverse design code by ensuring energy conservation for any working medium, like imperfect gases. The concept of loss coefficient for rotating impellers is introduced for improved loss modelling. The governing conservation equations for each component of a stage are presented, and then described in terms of an iterative procedure which calculates the required one-dimensional geometry. A graphical user interface which facilitates user input and presentation of results is discussed briefly. The object-oriented nature of the code is highlighted as a platform which easily provides for maintainability and future extensions.
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Bahamonde, Sebastian, Matteo Pini, Carlo De Servi i Piero Colonna. "Active subspaces for the optimal meanline design of unconventional turbomachinery". Applied Thermal Engineering 127 (grudzień 2017): 1108–18. http://dx.doi.org/10.1016/j.applthermaleng.2017.08.093.
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Cho, Soo-Yong, Bum-Seog Choi i Hyung-Soo Lim. "Off-Design Performance Analysis of a 7 MW Class Steam Turbine by Meanline Analysis". Journal of Power System Engineering 24, nr 2 (30.04.2020): 5–14. http://dx.doi.org/10.9726/kspse.2020.24.2.005.
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Lee, Sangkyoung, i Hal Gurgenci. "A comparison of three methodological approaches for meanline design of supercritical CO2 radial inflow turbines". Energy Conversion and Management 206 (luty 2020): 112500. http://dx.doi.org/10.1016/j.enconman.2020.112500.
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Deligant, Michael, Moritz Huebel, Tchable-Nan Djaname, Florent Ravelet, Mathieu Specklin i Mohamed Kebdani. "Design and off-design system simulation of concentrated solar super-critical CO2 cycle integrating a radial turbine meanline model". Energy Reports 8 (listopad 2022): 1381–93. http://dx.doi.org/10.1016/j.egyr.2022.07.141.
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Bahamonde, Sebastian, Matteo Pini, Carlo De Servi, Jürg Schiffmann i Piero Colonna. "Corrigendum to “Active subspaces for the optimal meanline design of unconventional turbomachinery” [Appl. Therm. Eng. 127 (2017) 1108–1118]". Applied Thermal Engineering 150 (marzec 2019): 1353–55. http://dx.doi.org/10.1016/j.applthermaleng.2018.12.099.
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Jung, Hyung-Chul, i Susan Krumdieck. "Meanline design of a 250 kW radial inflow turbine stage using R245fa working fluid and waste heat from a refinery process". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 230, nr 4 (10.03.2016): 402–14. http://dx.doi.org/10.1177/0957650916637966.
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Alawadhi, Khaled, Yousef Alhouli, Ali Ashour i 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, nr 11 (29.10.2020): 855. http://dx.doi.org/10.3390/jmse8110855.
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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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Large, James, i Apostolos Pesyridis. "Investigation of Micro Gas Turbine Systems for High Speed Long Loiter Tactical Unmanned Air Systems". Aerospace 6, nr 5 (14.05.2019): 55. http://dx.doi.org/10.3390/aerospace6050055.
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In this study, the on-going research into the improvement of micro-gas turbine propulsion system performance and the suitability for its application as propulsion systems for small tactical UAVs (<600 kg) is investigated. The study is focused around the concept of converting existing micro turbojet engines into turbofans with the use of a continuously variable gearbox, thus maintaining a single spool configuration and relative design simplicity. This is an effort to reduce the initial engine development cost, whilst improving the propulsive performance. The BMT 120 KS micro turbojet engine is selected for the performance evaluation of the conversion process using the gas turbine performance software GasTurb13. The preliminary design of a matched low-pressure compressor (LPC) for the proposed engine is then performed using meanline calculation methods. According to the analysis that is carried out, an improvement in the converted micro gas turbine engine performance, in terms of thrust and specific fuel consumption is achieved. Furthermore, with the introduction of a CVT gearbox, the fan speed operation may be adjusted independently of the core, allowing an increased thrust generation or better fuel consumption. This therefore enables a wider gamut of operating conditions and enhances the performance and scope of the tactical UAV.
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Liu, Yumin, Patrick Hendrick, Zhengping Zou i Frank Buysschaert. "A Reliable Update of the Ainley and Mathieson Profile and Secondary Correlations". International Journal of Turbomachinery, Propulsion and Power 7, nr 2 (21.04.2022): 14. http://dx.doi.org/10.3390/ijtpp7020014.
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Empirical correlations are still fundamental in the modern design paradigm of axial turbines. Among these, the prominent Ainley and Mathieson correlation (Ainley D. and Mathieson G., 1951, “A Method of Performance Estimation for Axial-Flow Turbines,” ARC Reports and Memoranda No. 2974) and its derivatives, plays a crucial role. In this paper, the underlying assumptions of the aforementioned models are discussed by means of a descriptive review, whilst an attempt is made to enhance their reliability and, potentially, accuracy in performance estimations. Closer investigation reveals an intriguing misuse of the lift coefficient in the secondary loss. In light of this, an enhanced model that, notably, builds upon the Zweifel criterion and the vortex penetration depth concept is developed and discussed. The obtained accuracy is subsequently assessed through CFD computations, employing a database comprising 109 cascades. The results indicate a 50% probability of achieving the ±15% error interval, which is twice as good as the most recent Aungier model (Aungier R., 2006, “Turbine Aerodynamics: Axial-Flow and Radial-Inflow Turbine Design and Analysis”, ASME Press, New York). Furthermore, the reliability of the proposed model is demonstrated by a reconstruction of the Smith chart, on the one hand, and a performance analysis, on the other. The reconstruction exhibits contours that conform to the original. The results of the performance study are compared with the CFD solutions of eight cascades working in off design conditions and confirm the need of the additionally included turbine design parameters, such as the axial velocity and the meanline radius ratios.
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Siddappaji, Kiran, i Mark G. Turner. "Versatile Tool for Parametric Smooth Turbomachinery Blades". Aerospace 9, nr 9 (31.08.2022): 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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Sun, J., i R. L. Elder. "Numerical optimization of a stator vane setting in multistage axial-flow compressors". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 212, nr 4 (1.06.1998): 247–59. http://dx.doi.org/10.1243/0957650981536772.
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This paper presents a numerical methodology for optimizing a stator stagger setting in a multistage axial-flow compressor environment. The method involves simultaneous resetting of several blade rows, which influences overall performance in a complex manner. The paper is presented in four parts: modelling the effect of stagger setting on individual stage performance, overall performance including surge point prediction, stagger setting optimization and numerical examples. The stage performance model is a one-dimensional meanline method where correlations are used to introduce real flow effects. The method uses (experimental or predicted) stage characteristics at design (nominal) setting to generate characteristics at other settings. A stage-by-stage model is used to ‘stack’ the stages together with a dynamic surge prediction model. A direct search method incorporating a sequential weight increasing factor technique (SWIFT) was then used to optimize stagger setting. The objective function in this optimization is penalized externally with an updated factor which helped to accelerate convergence. The methodology has been incorporated into a FORTRAN program and validated using data from a seven-stage aircraft compressor with hypothetical variable stagger vanes. Results have demonstrated that variable stagger is a powerful method to rematch stages which can be used to improve desired overall performance. Parametric studies on the optimization algorithm have also been conducted where it showed numerical stability and fast convergence.
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Benner, M. W., S. A. Sjolander i S. H. Moustapha. "An Empirical Prediction Method for Secondary Losses in Turbines—Part I: A New Loss Breakdown Scheme and Penetration Depth Correlation". Journal of Turbomachinery 128, nr 2 (1.02.2005): 273–80. http://dx.doi.org/10.1115/1.2162593.
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Despite its wide use in meanline analyses, the conventional loss breakdown scheme is based on a number of assumptions that are known to be physically unsatisfactory. One of these assumptions states that the loss generated in the airfoil surface boundary layers is uniform across the span. The loss results at high positive incidence presented in a previous paper (Benner, M. W., Sjolander, S. A., and Moustapha, S. H., 2004, ASME Paper No. GT2004-53786.) indicate that this assumption causes the conventional scheme to produce erroneous values of the secondary loss component. A new empirical prediction method for secondary losses in turbines has been developed, and it is based on a new loss breakdown scheme. In the first part of this two-part paper, the new loss breakdown scheme is presented. Using data from the current authors’ off-design cascade loss measurements, it is shown that the secondary losses obtained with the new scheme produce a trend with incidence that is physically more reasonable. Unlike the conventional loss breakdown scheme, the new scheme requires a correlation for the spanwise penetration depth of the passage vortex separation line at the trailing edge. One such correlation exists (Sharma, O. P., and Butler, T. L., 1987, ASME J. Turbomach., 109, pp. 229–236.); however, it was based on a small database. An improved correlation for penetration distance has been developed from a considerably larger database, and it is detailed in this paper.
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Hohenberg, Karl, Ricardo Martinez-Botas, Piotr Łuczyński, Carola Freytag i Manfred Wirsum. "Numerical and Experimental Investigation of a Low Order Radial Turbine Model for Engine-Level Optimization of Turbocharger Design". Journal of Engineering for Gas Turbines and Power 143, nr 10 (3.09.2021). http://dx.doi.org/10.1115/1.4051488.
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Abstract This paper presents the development and validation of a meanline model by means of numerical and experimental methods, to determine it's feasibility as an optimization tool for turbocharger matching. Using a parametric turbine model, numerical experiments were conducted accounting for variations of several key turbine design parameters and a wide operating range. The resulting dataset was used to test the accuracy of the meanline model when calibrated to a baseline design and thus evaluate it's ability of extrapolating to different designs. The loss models were examined in more detail, and a set of loss models which provided the most accurate results is presented. The meanline model was further validated experimentally using dynamometer test results of 6 turbine designs from the same parametric turbine model. The result showed that for design point and high power operation, an error of less than 3.1% and 2.0% was achieved for efficiency and mass flow parameters, respectively. This led to the conclusion that the model would be sufficiently accurate to represent design changes relevant to turbocharger matching.
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Meier zu Ummeln, Robert, Antoine Moreau i Markus Schnoes. "Influence of Different Flow Solvers and Off-Design Conditions On the Determination of Fan-Rotor Wakes for Broadband Noise Prediction". Journal of Engineering for Gas Turbines and Power, 26.09.2022. http://dx.doi.org/10.1115/1.4055753.
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Abstract The acoustic interaction of fan-rotor wakes with the downstream stator vanes is considered as an important noise source of an aircraft engine. The turbulence induced by the rotor generates a stochastic acoustic source that appears as broadband noise in the acoustic spectrum. During the preliminary design phase of an engine, established meanline and throughflow solvers usually do not resolve turbulence and associated unsteady flow parameters. But such solvers provide rotor pressure losses that can be used to estimate the mean and turbulent rotor wakes. A crucial step is the deduction of turbulence parameters from the mean wakes. A semi-empirical model for rotor-wake turbulence estimation is presented in this paper. The meanline method and the throughflow solver are compared to three-dimensional computational flow simulations investigating the capabilities of the different solvers to provide flow data for broadband wake interaction noise prediction. The methods are applied to a representative modern fan stage at a comprehensive number of operating points, comprising several speed lines from surge to choking conditions. Microphone measurements are consulted to assess the noise predictions. The evaluation confirms the applicability of the meanline and throughflow method in combination with the turbulence model for broadband noise estimation during the preliminary design phase. The underestimated turbulence in the tip region of the fan is found to be negligible even during off-design conditions.
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Ketata, Ahmed, i Zied Driss. "New FORTRAN meanline code for investigating the volute to rotor interspace effect on mixed flow turbine performance". Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 7.04.2021, 095440892110070. http://dx.doi.org/10.1177/09544089211007023.
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Mixed flow turbines are widely used in several industrial applications covering turbomachinery, automotive engineering and electricity production. For decades, it is well known that mixed flow turbines are a seat of several loss phenomena such as the volute to rotor interspace loss, subject of this paper. Commonly, the meanline approach is the first step solution for building a preliminary design of such turbines and estimating subsequent losses. The accuracy of the code used in the meanline modeling is crucial for building an optimized turbine design with a minimized loss generation. This paper presents an improved validated meanline code, written in the newest object-oriented version of the FORTRAN language, for turbomachinery performance prediction. Unlike commercially available codes, the code allows the calculation of the rotor passage loss coefficient given the turbine expansion ratio without the need for additional test data. The standard deviation value between the code and test data is less than 10%, for all studied cases which ensure the validity of the developed model. Then, the developed code is exploited to investigate the effect of the volute to rotor interspace geometry on the loss generation and performance of a mixed flow turbine. Indeed, a performance distribution over a wide range of rotational speed and an energy loss breakdown are depicted and discussed showing a significant impact of the volute to rotor interspace. The results revealed an improvement in the turbine efficiency up to 2.9% with a volute to rotor interspace radii ratio of 0.59 at 80% of the design speed.
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Alvarez-Regueiro, Eva, Bijie Yang, Maria Esperanza Barrera-Medrano, Ricardo F. Martinez-Botas i Srithar Rajoo. "Optimisation of an ORC Radial Turbine Using a Reduced-Order Model Coupled With CFD". Journal of Engineering for Gas Turbines and Power, 26.08.2022. http://dx.doi.org/10.1115/1.4055359.
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Abstract This paper presents the geometry optimisation of a single stage radial turbine for an Organic Ranking Cycle system operating over a pressure ratio of 9. The specific fluid used in this investigation is R1233zd (E), but the methodology applies to other organic fluids as well. The ORC system is used to recover excess waste heat from the operation of an offshore oil and gas platform in the gulf of Thailand and its conditions will be replicated at pilot plant level. The geometry is optimised for the highest total-to-static efficiency using non gradient based algorithms to allow for wide design space. Firstly, a 1D meanline geometry is optimised, which is followed by a Computational Fluid Dynamics (CFD) optimisation in 3D using a parameterised model. CFD validate and calibrate the meanline model as well as to understand the flow and the sensitivity of the design parameters not captured by the low-order model. Moreover, the flow field of the successful designs is analysed by CFD to identify the main flow structures that explain the difference in performance among the designs. The non-ideal gas thermophysical properties of R1233zd (E) are calculated using equations of state to account for the non-ideal gas behaviour.
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Ketata, Ahmed, i Zied Driss. "A methodology for loss and performance assessment of a variable geometry turbocharger turbine through a new meanline FORTRAN program". Engineering Computations, 11.11.2021. http://dx.doi.org/10.1108/ec-05-2021-0290.
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Purpose Variable geometry turbine (VGT), a key component of modern internal combustion engines (ICE) turbochargers, is increasingly used for better efficiency and reduced exhaust gas emissions. The aim of this study is the development of a new meanline FORTRAN code for accurate performance and loss assessment of VGTs under a wider operating range. This code is a useful alternative tool for engineers for fast design of VGT systems where higher efficiency and minimum loss are being required. Design/methodology/approach The proposed meanline code was applied to a variable geometry mixed flow turbine at different nozzle vane angles and under a wide range of rotational speed and the expansion ratio. The numerical methodology was validated through a comparison of the predicted performance to test data. The maps of the mass flow rate as well as the efficiency of the VGT system are discussed for different nozzle vane angles under a wide range of rotational speed. Based on the developed model, a breakdown loss analysis was carried out showing a significant effect of the nozzle vane angle on the loss distribution. Findings Results indicated that the nozzle angle of 70° has led to the maximum efficiency compared to the other investigated nozzle vane angles ranging from 30° up to 80°. The results showed that the passage loss was significantly reduced as the nozzle vane angle increases from 30° up to 70°. Originality/value This paper outlines a new meanline approach for variable geometry turbocharger turbines. The developed code presents the novelty of including the effect of the vane radii variation, due to the pivoting mechanism of the nozzle ring. The developed code can be generalized to either radial or mixed flow turbines with or without a VGT system.
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Taddei, Simone Rosa. "Time-marching solution of transonic flows at axial turbomachinery meanline". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 9.12.2020, 095441002097735. http://dx.doi.org/10.1177/0954410020977350.
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A new blade force model is coupled to quasi-one dimensional Euler equations for a variable geometry flowpath. After analytical inclusion of the blade force, the flow equations take a strictly one-dimensional form with specific expressions of the convective flux and blade load source terms. Regardless of the flow turning, that is simply achieved by the load source term as an explicit function of the blade camber, the new form describes a perfect analogy between the average flow inside a blade passage and strictly one-dimensional flows, especially concerning wave propagation. This property allows capture of passage choking and shocks. Other types of shock more important for turbomachinery analysis, like leading edge strong shocks in compressors and trailing edge weak shocks in choked turbines, are modelled by properly matching the new set of equations inside blade regions with the standard quasi-one dimensional equations outside. Upon specification of viscous losses and subsonic deviations fitted from experimental results, the model predicts the choke mass flow of a transonic compressor stage (NASA stage 37) at a 0.1% to 0.4% accuracy both in the absence and in the presence of the leading edge shock. This result supports the effectiveness of the leading edge shock model. The accuracy on choke mass flow would decrease to around 1% if empirical input was specified from open-literature experimental correlations. The model captures the typical trend of exit angle with total pressure ratio for a choked turbine (NASA Lewis two-stage). This result involves satisfactory prediction of not only choke mass flow, but also trailing edge shock loss and supersonic deviation. The complete turbine operational map in terms of shaft torque and pressure ratio is also re-obtained with noticeable accuracy except in strong off-design conditions, where experimental correlations likely fail.
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Lee, Changgu, Selin Arslan i Luc G. Fréchette. "Design Principles and Measured Performance of Multistage Radial Flow Microturbomachinery at Low Reynolds Numbers". Journal of Fluids Engineering 130, nr 11 (23.09.2008). http://dx.doi.org/10.1115/1.2979010.
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This paper introduces and experimentally demonstrates the design concept of multistage microturbomachinery, which is fabricated using silicon microfabrication technology. The design process for multistage microscale turbomachinery based on meanline analysis is presented, along with computational fluid dynamics predictions of the key aerodynamic performance parameters required in this design process. This modeling was compared with a microturbine device with a 4 mm diameter rotor and 100 μm chord blades, based on microelectromechanical system technology, which was spun to 330,000 rpm and produced 0.38 W of mechanical power. Modeling suggests a turbine adiabatic efficiency of 35% and Re=266 at the maximum speed. The pressure distribution across the blade rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 W with an adiabatic efficiency of 63% at a rotor speed of 1.1×106 rpm.
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Ventura, Carlos A. M., Peter A. Jacobs, Andrew S. Rowlands, Paul Petrie-Repar i Emilie Sauret. "Preliminary Design and Performance Estimation of Radial Inflow Turbines: An Automated Approach". Journal of Fluids Engineering 134, nr 3 (1.03.2012). http://dx.doi.org/10.1115/1.4006174.
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A comprehensive one-dimensional meanline design approach for radial inflow turbines is described in the present work. An original code was developed in Python that takes a novel approach to the automatic selection of feasible machines based on pre-defined performance or geometry characteristics for a given application. It comprises a brute-force search algorithm that traverses the entire search space based on key non-dimensional parameters and rotational speed. In this study, an in-depth analysis and subsequent implementation of relevant loss models as well as selection criteria for radial inflow turbines is addressed. Comparison with previously published designs, as well as other available codes, showed good agreement. Sample (real and theoretical) test cases were trialed and results showed good agreement when compared to other available codes. The presented approach was found to be valid and the model was found to be a useful tool with regards to the preliminary design and performance estimation of radial inflow turbines, enabling its integration with other thermodynamic cycle analysis and three-dimensional blade design codes.
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Karaefe, Renan Emre, Pascal Post, Francesca di Mare, Valerius Venzik, Paul Wotzka, Dirk Müller i Riley Bradley Barta. "On Integrated Fluid Screening and Turbomachinery Design for Optimized Industrial Heat Pumps". Journal of Engineering for Gas Turbines and Power, 27.09.2022. http://dx.doi.org/10.1115/1.4055795.
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Abstract This work presents an approach to the contextual integration of fluid selection and compressor design for the cycle design of efficient industrial heat pumps. The vapor-compression cycle of an air-water heat pump operated at 42 °C source and 82 °C target temperature is investigated as a theoretical case study. An optimization study is performed, which includes the assessment of suitable refrigerants. Besides well-known single-component refrigerants, various binary mixtures are considered. The cycle optimization aims at simultaneously providing high cycle coefficient of performance and volumetric heating capacity. Cycle operation with the mixtures R-41/Trans-2-Butene (10, 90) mol % and CO2/R-161 (40, 60) mol % yields the highest values of these parameters, respectively. For further evaluation, centrifugal compressors operated with each of the two promising mixtures are designed with an in-house meanline program. In addition, the compressor design for the hydrofluoro-olefin refrigerant R-1234ze(Z) is considered as a reference. All designs are reviewed with respect to cycle as well as compressor design criteria and the applied methodology will assist designers in identifying key decision variables. The comprehensive design assessment suggests that CO2/R-161 (40, 60) mol % provides the best overall solution for an efficient cycle with a compact compressor design.
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Lampe, Matthias, Carlo De Servi, Johannes Schilling, André Bardow i Piero Colonna. "Toward the Integrated Design of Organic Rankine Cycle Power Plants: A Method for the Simultaneous Optimization of Working Fluid, Thermodynamic Cycle, and Turbine". Journal of Engineering for Gas Turbines and Power 141, nr 11 (8.10.2019). http://dx.doi.org/10.1115/1.4044380.
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Abstract The conventional design of organic Rankine cycle (ORC) power systems starts with the selection of the working fluid and the subsequent optimization of the corresponding thermodynamic cycle. More recently, systematic methods have been proposed integrating the selection of the working fluid into the optimization of the thermodynamic cycle. However, in both cases, the turbine is designed subsequently. This procedure can lead to a suboptimal design, especially in the case of mini- and small-scale ORC systems, since the preselected combination of working fluid and operating conditions may lead to infeasible turbine designs. The resulting iterative design procedure may end in conservative solutions after multiple trial-and-error attempts due to the strong interdependence of the many design variables and constraints involved. In this work, we therefore present a new design and optimization method integrating working fluid selection, thermodynamic cycle design, and preliminary turbine design. To this purpose, our recent 1-stage continuous-molecular targeting (CoMT)-computer-aided molecular design (CAMD) method for the integrated design of the ORC process and working fluid is expanded by a turbine meanline design procedure. Thereby, the search space of the optimization is bounded to regions where the design of the turbine is feasible. The resulting method has been tested for the design of a small-scale high-temperature ORC unit adopting a radial-inflow turbo-expander. The results confirm the potential of the proposed method over the conventional iterative design practice for the design of small-scale ORC turbogenerators.
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Massoudi, Soheyl, Cyril Picard i Jürg Schiffmann. "Robust design using multiobjective optimisation and artificial neural networks with application to a heat pump radial compressor". Design Science 8 (2022). http://dx.doi.org/10.1017/dsj.2021.25.
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Abstract Although robustness is an important consideration to guarantee the performance of designs under deviation, systems are often engineered by evaluating their performance exclusively at nominal conditions. Robustness is sometimes evaluated a posteriori through a sensitivity analysis, which does not guarantee optimality in terms of robustness. This article introduces an automated design framework based on multiobjective optimisation to evaluate robustness as an additional competing objective. Robustness is computed as a sampled hypervolume of imposed geometrical and operational deviations from the nominal point. In order to address the high number of additional evaluations needed to compute robustness, artificial neutral networks are used to generate fast and accurate surrogates of high-fidelity models. The identification of their hyperparameters is formulated as an optimisation problem. In the frame of a case study, the developed methodology was applied to the design of a small-scale turbocompressor. Robustness was included as an objective to be maximised alongside nominal efficiency and mass-flow range between surge and choke. An experimentally validated 1D radial turbocompressor meanline model was used to generate the training data. The optimisation results suggest a clear competition between efficiency, range and robustness, while the use of neural networks led to a speed-up by four orders of magnitude compared to the 1D code.
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Liu, Yu Min, Patrick Hendrick, Zhengping Zou i Frank Buysschaert. "Statistical and Computational Evaluation of Empirical Axial Turbine Correlations in Design of Centrifugal Turbines". Journal of Turbomachinery, 23.09.2021, 1–31. http://dx.doi.org/10.1115/1.4052525.
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Abstract Centrifugal turbines have recently regained interest of the engineering community as they could serve as cost-effective alternatives in diverse energy applications. In this device, the working fluid expands in a centrifugal flowpath and entails rotation of concentric rings of airfoil-shaped blades. Yet in their current design paradigm, their meanline performance estimation and optimisation have dubiously exploited axial turbine empirical loss correlations. To the authors knowledge, there are no theoretical nor practical foundation that could justify such practice. Hence, this paper intends to deliver an answer on this matter with application of the traditional and biased Kacker & Okapuu(KO) and Aungier(Ag) correlations on 33 pairs of geometrically similar axial and centrifugal cascades. The uncovered content is twofold. First, the Ag loss has a probability of achieving an error of within ±15% error of 44% whereas the KO loss is lessened to 38%. The Ag deviation attains 15% which is thrice that of the KO. In second, the insensitivity of the profile and secondary loss correlations under drastic change of flow condition in the centrifugal cascades is proven to be practically significant. While the Ag deviation is still able to reach an accuracy of 11%. Thereupon, the empirical axial turbine loss correlations must not be used for performance estimation nor optimisation of centrifugal turbines.
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Ghoreyshi, Seyed M., i Meinhard T. Schobeiri. "The ultra-high efficiency gas turbine engine, UHEGT, part I: Design and numerical analysis of the multistage system". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 27.08.2020, 095765092095166. http://dx.doi.org/10.1177/0957650920951666.
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The Ultra-High Efficiency Gas Turbine Engine (UHEGT) was introduced in our previous studies. In UHEGT, the combustion process is no longer contained in isolation between the compressor and turbine. It is rather distributed in multiple stages and integrated within the high-pressure turbine stator rows. Compared to the current most advanced conventional gas turbines, UHEGT considerably improves the efficiency and output power of the engine while reducing its emissions and size. In this study, a six-stage UHEGT turbine with three stages of stator internal combustion is designed and analyzed. The design represents a single spool turboshaft system for power generation using gaseous fuels. The preliminary flow path for each turbine stage is designed by the meanline approach and modified using Computational Fluid Dynamics (CFD). Unsteady CFD calculation (via commercial software ANSYS CFX) is used to simulate and optimize the flow and combustion process through high-pressure turbine stages. The results show a base thermal efficiency of above 45% is achieved. It shows a successful integration of the multi-stage combustion process into the high-pressure turbine stages and a highly uniform temperature distribution at the inlet of each rotor row. High temperatures in some areas on the stator blade surfaces are controlled using indexing of fuel injectors and stator blades.
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Harrison, Herbert, i Nicole L. Key. "A New Approach to Modeling Slip and Work Input for Centrifugal Compressors". Journal of Engineering for Gas Turbines and Power, 21.12.2020. http://dx.doi.org/10.1115/1.4049412.
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Abstract A new method of modeling slip factor and work input for centrifugal compressor impellers is presented. Rather than using geometry to predict the behavior of the flow at the impeller exit, the new method leverages governing relationships to predict the work input delivered by the impeller with dimensionless design parameters. The approach incorporates both impeller geometry and flow conditions and, therefore, is inherently able to predict the slip factor both at design and off-design conditions. Five impeller cases are used to demonstrate the efficacy of the method, four of which are well documented in the open literature. Multiple implementations of the model are introduced to enable users to customize the model to specific applications. Significant improvement in the accuracy of the prediction of slip factor and work input is obtained at both design and off-design conditions relative to Wiesner's slip model. While Wiesner's model predicts the slip factor of 52% of the data within ±0.05 absolute error, the most accurate implementation of the new model predicts 99% of the data within the same error band. The effects of external losses on the model are considered, and the new model is fairly insensitive to the effects of external losses. Finally, detailed procedures to incorporate the new model into a meanline analysis tool are provided in the appendices.
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Badum, Lukas, Boris Leizeronok i Beni Cukurel. "New Insights From Conceptual Design of an Additive Manufactured 300 W Micro Gas Turbine Towards UAV Applications". Journal of Engineering for Gas Turbines and Power, 7.10.2020. http://dx.doi.org/10.1115/1.4048695.
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Abstract Owing to high energy density of hydrocarbon fuels, ultra-micro gas turbines with power outputs below 1 kW have potential as battery replacement in drones. To overcome the obstacles observed in previous works on gas turbines of this scale, novel gas turbine architecture is proposed based on conventional roller bearing technology that operates at up to 500,000 RPM and additively manufactured monolithic rotor in cantilevered configuration, equipped with internal cooling blades. The optimum turbomachinery design is elaborated using diabatic cycle calculation, coupled with turbomachinery meanline design. This approach provides new insights on interdependencies of heat transfer, component efficiency and system electric efficiency. Thereby, reduced design pressure ratio of 2.5 with 1200 K turbine inlet temperature is identified as most suitable for 300 W electric power output. In following, material properties and design constraints for the monolithic rotor are obtained from available additive manufacturing technologies. Rotordynamic simulations are then conducted for four available materials using simplified rotor model. CFD simulations are conducted to quantify compressor efficiency and conjugate heat transfer analysis is performed to assess the benefit of internal cooling cavity and vanes for different rotor materials. It is demonstrated that the cavity flow absorbs large heat flux from turbine to compressor, thus cooling the rotor structure and improving the diabatic cycle efficiency. Finally, results of this conceptual study show that ultra-micro gas turbine with electric efficiency of up to 5% is feasible, while energy density is increased by factor of 3.6, compared to lithium-ion batteries.
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Asli, Majid, i Panagiotis Stathopoulos. "An Optimization Methodology for Turbines Driven by Pulsed Detonation Combustors". Journal of Engineering for Gas Turbines and Power, 3.09.2022. http://dx.doi.org/10.1115/1.4055490.
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Abstract A step-change in efficiency of gas turbine technology and, subsequently, an emissions reduction from this technology requires conceptual changes. Substituting conventional combustion chambers with pressure gain combustion in the form of pulsed detonation combustion (PDC) is one of the promising methods that can reduce gas turbine emissions significantly. Nevertheless, the component matching for the respective systems and specifically that of turbine expanders working with the exhaust flow of PDC tubes is still not solved. The unsteady nature of PDC exhaust flow makes 3D-CFD simulations too expensive to be applied in optimization loops in early design stages. To address this question, the present paper introduces a new cost-effective but reliable methodology for turbine analysis and optimization, based on the unsteady exhaust flow of pulsed detonation combustors. The methodology unitizes a robust unsteady one-dimensional solver, a meanline performance analysis, and an adaptive surrogate optimization algorithm. A two-stage axial turbine is optimized considering all unsteady flow features of a hydrogen-air PDC configuration with five PDC tubes. A three-dimensional URANS simulation is performed for the optimized geometry and the baseline to evaluate the methodology. The results showed that the optimized turbine produces 16% lower entropy than the original one. Additionally, the turbine output power is increased by 14% by the optimized design. Based on the results, it is concluded that the approach is fast and reliable enough to be applied in optimizing any turbine working with unsteady flows, more specifically in PDC applications.
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De Servi, Carlo M., Matteo Burigana, Matteo Pini i Piero Colonna. "Design Method and Performance Prediction for Radial-Inflow Turbines of High-Temperature Mini-Organic Rankine Cycle Power Systems". Journal of Engineering for Gas Turbines and Power 141, nr 9 (2.08.2019). http://dx.doi.org/10.1115/1.4043973.
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The realization of commercial mini organic Rankine cycle (ORC) power systems (tens of kW of power output) is currently pursued by means of various research and development activities. The application driving most of the efforts is the waste heat recovery from long-haul truck engines. Obtaining an efficient mini radial inflow turbine, arguably the most suitable type of expander for this application, is particularly challenging, given the small mass flow rate, and the occurrence of nonideal compressible fluid dynamic effects in the stator. Available design methods are currently based on guidelines and loss models developed mainly for turbochargers. The preliminary geometry is subsequently adapted by means of computational fluid-dynamic calculations with codes that are not validated in case of nonideal compressible flows of organic fluids. An experimental 10 kW mini-ORC radial inflow turbine will be realized and tested in the Propulsion and Power Laboratory of the Delft University of Technology, with the aim of providing measurement datasets for the validation of computational fluid dynamics (CFD) tools and the calibration of empirical loss models. The fluid dynamic design and characterization of this machine is reported here. Notably, the turbine is designed using a meanline model in which fluid-dynamic losses are estimated using semi-empirical correlations for conventional radial turbines. The resulting impeller geometry is then optimized using steady-state three-dimensional computational fluid dynamic models and surrogate-based optimization. Finally, a loss breakdown is performed and the results are compared against those obtained by three-dimensional unsteady fluid-dynamic calculations. The outcomes of the study indicate that the optimal layout of mini-ORC turbines significantly differs from that of radial-inflow turbines (RIT) utilized in more traditional applications, confirming the need for experimental campaigns to support the conception of new design practices.
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Harley, Peter, Stephen Spence, Dietmar Filsinger, Michael Dietrich i Juliana Early. "Meanline Modeling of Inlet Recirculation in Automotive Turbocharger Centrifugal Compressors". Journal of Turbomachinery 137, nr 1 (4.09.2014). http://dx.doi.org/10.1115/1.4028247.
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This study provides a novel meanline modeling approach for centrifugal compressors. All compressors analyzed are of the automotive turbocharger variety and have typical upstream geometry with no casing treatments or preswirl vanes. Past experience dictates that inducer recirculation is prevalent toward surge in designs with high inlet shroud to outlet radius ratios; such designs are found in turbocharger compressors due to the demand for operating range. The aim of the paper is to provide further understanding of impeller inducer flow paths when operating with significant inducer recirculation. Using three-dimensional (3D) computational fluid dynamics (CFD) and a single-passage model, the flow coefficient at which the recirculating flow begins to develop and the rate at which it grows are used to assess and correlate work and angular momentum delivered to the incoming flow. All numerical modeling has been fully validated using measurements taken from hot gas stand tests for all compressor stages. The new modeling approach links the inlet recirculating flow and the pressure ratio characteristic of the compressor. Typically for a fixed rotational speed, between choke and the onset of impeller inlet recirculation the pressure ratio rises gradually at a rate dominated by the aerodynamic losses. However, in modern automotive turbocharger compressors where operating range is paramount, the pressure ratio no longer changes significantly between the onset of recirculation and surge. Instead the pressure ratio remains relatively constant for reducing mass flow rates until surge occurs. Existing meanline modeling techniques predict that the pressure ratio continues to gradually rise toward surge, which when compared to test data is not accurate. A new meanline method is presented here which tackles this issue by modeling the direct effects of the recirculation. The result is a meanline model that better represents the actual fluid flow seen in the CFD results and more accurately predicts the pressure ratio and efficiency characteristics in the region of the compressor map affected by inlet recirculation.
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Stuart, Charles, Stephen Spence, Dietmar Filsinger, Andre Starke i Sung In Kim. "Characterizing the Influence of Impeller Exit Recirculation on Centrifugal Compressor Work Input". Journal of Turbomachinery 140, nr 1 (25.10.2017). http://dx.doi.org/10.1115/1.4038120.
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Impeller recirculation is a loss which has long been considered in one-dimensional (1D) modeling; however, the full extent of its impact on stage performance has not been analyzed. Recirculation has traditionally been considered purely as a parasitic (or external) loss, i.e., one which absorbs work but does not contribute to total pressure rise across the stage. Having extensively analyzed the impact of recirculation on the impeller exit flow field, it was possible to show that it has far-reaching consequences beyond that of increasing total temperature. The overall aim of this package of work is to apply a much more physical treatment to the impact of impeller exit recirculation (and the aerodynamic blockage associated with it) and hence realize an improvement in the 1D stage performance prediction of a number of turbocharger centrifugal compressors. The factors influencing the presence and extent of this recirculation are numerous, requiring detailed investigations to successfully understand its sources and to characterize its extent. A combination of validated three-dimensional computational fluid dynamics (CFD) data and gas stand test data for six automotive turbocharger compressor stages was employed to achieve this aim. In order to capture the variation of the blockage presented to the flow with both geometry and operating condition, an approach involving the impeller outlet to inlet area ratio and a novel flow coefficient term were employed. The resulting data permitted the generation of a single equation to represent the impeller exit blockage levels for the entire operating map of all the six compressor stages under investigation. With an understanding of the extent of the region of recirculating flow realized and the key drivers leading to its creation identified, it was necessary to comprehend how the resulting blockage influenced compressor performance. Consideration was given to the impact on impeller work input through modification of the impeller exit velocity triangle, incorporating the introduction of the concept of an “aerodynamic meanline” to account for the reduction in the size of the active flow region due to the presence of blockage. The sensitivity of the stage to this change was then related back to the level of backsweep applied to the impeller. As a result of this analysis, the improvement in the 1D performance prediction of the six compressor stages is demonstrated. In addition, a number of design recommendations are presented to ensure that the detrimental effects associated with the presence of impeller exit recirculation can be minimized.