Gotowe bibliografie tematyczne / Vaneless diffusers

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Gotowa bibliografia na temat „Vaneless diffusers”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "Vaneless diffusers"

Калінкевич, Микола Васильович, i Микола Іванович Радченко. "ЗБІЛЬШЕННЯ ДІАПАЗОНУ СТІЙКОЇ РОБОТИ СТУПЕНЯ ВІДЦЕНТРОВОГО КОМПРЕСОРА З БЕЗЛОПАТКОВИМ ДИФУЗОРОМ". Aerospace technic and technology, nr 6 (24.12.2019): 4–9. http://dx.doi.org/10.32620/aktt.2019.6.01.

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Centrifugal compressors often operate at different capacities, so it is important to ensure their stable operation over a wide flow range. Stages with vaneless diffusers have several advantages compared to stages with other types of diffusers: they are more technologically advanced to manufacture, and more uniform pressure distribution behind the impeller improves the dynamics of the rotor. At low flows, due to the occurrence of a rotating stall and surge, the efficiency of stages with vaneless diffusers rapidly decreases. The occurrence of unstable operating modes of centrifugal compressor stages at low flow rates is associated with the appearance of developed backflows in the flow part. To expand the range of stable operation of the stages, it is necessary to use methods of flow separation control. Separation of the flow can be controlled either by special profiling the flow part channels or by actively influencing the flow, for example, by injecting gas. To solve this problem, a mathematical model of the gas flow in a vaneless diffuser with gas injection is developed. The characteristics and parameters of the flow in the vaneless diffusers with various meridional profiles with and without injecting gas were calculated. A comparison of the calculated and experimental characteristics of the vaneless diffusers and flow parameters in diffusers with different geometries and with different injection modes confirms the adequacy of the mathematical model. Investigations have confirmed the possibility of improving the characteristics of the stages of centrifugal compressors through the use of vaneless diffusers and diffusers with gas injection. Gas injection diffusers extend the stable operation range of the stages. The use of gas injection in a vaneless diffuser allows reducing the power consumption during antisurge control in comparison with the widespread bypass suction system at the entrance to the impeller

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Galerkin, Y. B., A. F. Rekstin i O. A. Solovyeva. "Selecting the Dimensions of the Vaneless Diffuser of a Centrifugal Compressor Stage at the Primary Design Phase". Proceedings of Higher Educational Institutions. Маchine Building, nr 10 (715) (październik 2019): 43–57. http://dx.doi.org/10.18698/0536-1044-2019-10-43-57.

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The advances in the primary design method of centrifugal compressors of the Universal Modeling Method have led to the need to analyze and revise the recommendations for the optimal size and configuration selection of vaneless diffusers of centrifugal compressor stages. The results of CFD calculations of a family of vaneless diffusers with different relative width, radial length, velocity coefficients and flow angles at the inlet are used to develop new recommendations. The choice of the optimal width of the vaneless diffuser is based on ensuring a non-separable flow in it at the boundary of the surge. The optimal value of the relative radial length of the diffuser is in the range of 1.65–2.0. Considering the above, a formula for selecting the vaneless diffuser outer diameter is proposed depending on the design flow rate coefficient. The developed primary design method of vaneless diffusers is included in the software programs of the Universal Modeling Method and is used in design and research practice.

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Zhang, Qian, Liang Zhang, Qiuhong Huo i Lei Zhang. "Study on Two Types of Stall Patterns in a Centrifugal Compressor with a Wide Vaneless Diffuser". Processes 8, nr 10 (4.10.2020): 1251. http://dx.doi.org/10.3390/pr8101251.

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Two types of stall patterns in the centrifugal compressor with a wide vaneless diffuser were numerically studied in this paper. We carried out kinds of three-dimensional numerical simulations of the instability process in wide vaneless diffusers with different radius ratios. The results show that there are two kinds of stall patterns in wide vaneless diffusers with different radius ratios. For a short diffuser with a radius ratio of 1.5, the speed of the propagation of stalled cells is relatively high, and the propagation speed and frequency of stall cells do not change with the decrease in the flow rate. For a long diffuser with a radius ratio of 1.8, the propagation velocity of stall cells is smaller to the one in the short diffuser, and increases with the decrease in flow rate. For wide vaneless diffusers with different radius ratios, the main factor causing stall is the outlet reflux. Reducing the radius ratio of the wide vaneless diffuser has an important influence on the stability of the centrifugal compressor.

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Engeda, A. "The design and performance results of simple flat plate low solidity vaned diffusers". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 215, nr 1 (1.02.2001): 109–18. http://dx.doi.org/10.1243/0957650011536471.

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Vaned diffusers for centrifugal compressors have decades of development history, but most of it is of a proprietary and empirical nature. Centrifugal compressor designers are continuously searching for a diffuser system that combines the good qualities of vaneless and vaned diffuser systems. Vaneless diffusers are known to possess wide operating range with relatively low efficiency while current conventional vaned diffusers have narrow range and high efficiency. The low solidity vaned diffuser (LSVD) has shown good performance from both range and efficiency standpoints. Its relatively high efficiency and wide flow range potentials are strong current factors, leading the compressor manufacturer to seriously consider it as the best compromise diffuser that has been sought through the years. This paper discusses the design and experimental performance results of eight flat plate LSVDs. These diffusers had a solidity of 0.9, 0.8, 0.7 and 0.6. Eight low solidity vaned diffusers (LSVD1 to LSVD8) and for comparison purposes two vaneless diffusers (VNL1 and VNL2) and a conventional vaned diffuser (CVND) were all tested downstream of the same impeller at three speeds.

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Zhu, Xiaocheng, Chenxing Hu i Zhaohui Du. "Formation and suppression of the instability in radial vaneless diffusers". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, nr 12 (10.02.2019): 4606–22. http://dx.doi.org/10.1177/0954410019827390.

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The change of width radius ratio may lead to different physical mechanisms for the instabilities in vaneless diffusers. Reynolds-averaged Navier–Stokes numerical simulations were performed and the results were used to present the mean flow. A quasi-laminar mixed approach based was applied on the vaneless diffusers with narrow and moderate width. The frequency of the perturbations in the vaneless diffuser flow with different axial widths was validated against the experimental data. Moreover, in order to reveal the wavemaker region, the structural sensitivity analysis of the vaneless diffuser flow was carried out. The sensitivity of the eigenvalue to the mean flow modifications were used to guide the flow control. The results indicate that the viscosity tends to stabilize the narrow diffusers but destabilize the moderate width diffusers. For narrow diffusers, the wavemaker regions lie at the centerline near the intersection region of boundary layers. However, the wavemaker regions lie beside the centerline for moderate width diffusers. The occurrence of instabilities may be related with the inflection point of the velocity distribution in axial direction. Given the distribution of the sensitivity to mean flow modifications, the flow control effect may be associated with the amplitude of viscosity stress at the local flow field.

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Seralathan, S., i D. G. Roy Chowdhury. "Numerical Study on the Effect of Free Rotating Vaneless Diffuser of Exit Diameter to Inlet Diameter Ratio 1.3 with Speed Ratio 0.50 on Centrifugal Compressor Performance". Applied Mechanics and Materials 813-814 (listopad 2015): 1063–69. http://dx.doi.org/10.4028/www.scientific.net/amm.813-814.1063.

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Innovative methods in the design of radial diffuser are necessary for reducing the energy losses associated with diffusion in order to design an efficient centrifugal compressor. Rotating vaneless diffusers is one such concept, in which a particular type, free rotating vaneless diffuser, the diffuser speed becomes a fraction of the rotating impeller speed and rotates independently. In this paper, an impeller with stationary vaneless diffuser alone of diffuser diameter ratio 1.40 and the same impeller with a freely rotating vaneless diffuser of diffuser diameter ratio 1.30 along with stationary vaneless diffuser at downstream for the remaining radius ratio are analyzed for flow diffusion and performance. Higher static pressure rise with reduced stagnation pressure losses and a marginally lesser efficiency by around 3.5% compared to SVD is achieved by the free rotating vaneless diffuser configuration (FRVD30SR0.5).

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Solovyeva, О. А., А. А. Drozdov, E. Yu Popova i K. V. Soldatova. "CFD-model of Vaneless Diffuser of Centrifugal Compressor". Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, nr 2 (137) (czerwiec 2021): 109–30. http://dx.doi.org/10.18698/0236-3941-2021-2-109-130.

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The centrifugal compressor design involves the use of approximate engineering techniques based on mathematical modeling. One of such techniques is the universal modeling method, which proves to be practically applicable. Having generalized a series of CFD calculations, we used a mathematical model in the latest version of the compressor model to calculate flow parameters in vaneless diffusers. The diffuser model was identified based on the results of experimental studies of average-flow model stages carried out at SPbPU. The model is also used to calculate Clark low-flow centrifugal compressor stages with narrow diffusers with a relative width in the range of 0.5--2.0 %. For these stages, the developed mathematical model showed insufficient efficiency, since the dimensions of the diffusers go beyond the limits of its applicability. To solve this problem, we calculated a series of vaneless diffusers with a relative width in the range of 0.6--1.2 % in the ANSYS CFX software package. Relying on the results of CFD calculations, we plotted the gas dynamic characteristics of the loss coefficients and changes in the flow angle depending on the flow angle at the inlet to the vaneless diffuser. To process the calculated data, the method of regression analysis was applied, with the help of which a system of algebraic equations was developed that connects geometric, gas-dynamic parameters and similarity criteria. The obtained equations are included in a new mathematical model of the universal modeling method for calculating the flow parameters of vaneless diffusers. Comparison of the calculated gas-dynamic characteristics according to the new model with experimental data showed the average error of modeling the calculated (maximum) efficiency equal to 1.08 %

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Pinarbasi, A., i M. W. Johnson. "Three-Dimensional Flow Measurements in Conical and Straight Wall Centrifugal Compressor Vaneless Diffusers". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 210, nr 1 (styczeń 1996): 51–61. http://dx.doi.org/10.1243/pime_proc_1996_210_169_02.

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In the current work three-dimensional flow measurements in two types of centrifugal compressor vaneless diffuser were obtained using hot wire anemometry. The first diffuser was conical, designed to give a constant flow area, while the second straight wall diffuser had a constant axial width. Measurements of mean velocity, flow angle and velocity fluctuation level were obtained on eight cross-sectional planes in each diffuser. The jet-wake flow pattern and the impeller blade wakes are clearly visible at the inlet of both diffusers. Mixing out of the blade wake proceeds more rapidly in the straight diffuser. The hub boundary layer also develops more rapidly in this diffuser because of the adverse pressure gradient. Velocity fluctuation level measurements highlight the mixing regions within the diffusers. Recommendations are also made for the design of vaned diffusers. A larger vaneless space would be required with a straight wall diffuser and significant twisting of the vane would be required for both diffuser geometries if significant incidence losses are to be avoided.

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Dou, H. S., i S. Mizuki. "Analysis of the Flow in Vaneless Diffusers With Large Width-to-Radius Ratios". Journal of Turbomachinery 120, nr 1 (1.01.1998): 193–201. http://dx.doi.org/10.1115/1.2841381.

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The flow in vaneless diffusers with large width-to-radius ratios is analyzed by using three-dimensional boundary-layer theory. The variations of the wall shear angle in the layer and the separation radius of the turbulent boundary layer versus various parameters are calculated and compared with experimental data. The effect of the separation point on the performance of vaneless diffusers and the mechanism of rotating stall are discussed. It is concluded that when the flow rate becomes very low, the reverse flow zone on the diffuser walls extends toward the entry region of diffusers. When the rotating jet-wake flow with varying total pressure passes through the reverse flow region near the impeller outlet, rotating stall is generated. The influences of the radius ratio on the reverse flow occurrence as well as on the overall performance are also discussed.

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Zhang, Qian, Qiuhong Huo, Lei Zhang, Lei Song i Jianmeng Yang. "Effect of Vaneless Diffuser Shape on Performance of Centrifugal Compressor". Applied Sciences 10, nr 6 (12.03.2020): 1936. http://dx.doi.org/10.3390/app10061936.

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The influence of four different vaneless diffuser shapes on the performance of centrifugal compressors is numerically studied in this paper. One of the studied shapes was a parallel wall diffuser. Two others had the width reduced only from hub and shroud and the rest had the width reduced from hub and shroud divided evenly. Then the numerical simulation was employed and the overall compressor aerodynamic performance was studied. The detailed velocity and pressure distribution and energy loss within the centrifugal compressor with different diffuser geometries and different operating conditions were analyzed. The results revealed that shroud pinch significantly improved the overall compressor aerodynamic performance more than any other pinch types, and the best performance can be achieved by pinched diffusers under the design condition compared with pinched diffusers under the near surge condition or choking condition. The range of energy loss, namely the static entropy area in the compressor, become reduced with the above three pinches diffusers.

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Rozprawy doktorskie na temat "Vaneless diffusers"

Pinarbasi, Ali. "Flow investigation in centrifugal compressor vaneless and vaned diffusers". Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284261.

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He, Ning. "Impeller diffuser interactions in high speed centrifugal compressors". Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/11403.

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In the current research work, a computational analysis of a high-speed centrifugal compressor stage for turbocharger applications is presented. A detailed investigation about the interactions between backswept impeller and downstream vaneless and vaned diffusers is carried out. ' A unshrouded backswept impeller with splitters was combined with a vaneless diffuser or a number of different designs of vaned diffusers. The CFD solver CFX-TASCow was used. The three-dimensional Reynolds- Averaged Navier-Stokes equations are solved and a pressure correction method is employed to solve the system of equations. A steady simulation and analysis of the interactions between the impeller and the vaneless diffuser is carried out, emphasis is focused on the comparisons of the different interactions at different conditions regarding the flow structures at different radius ratios, effect of rotational speed, mass flow rate and impeller tip clearance. The predicted results were also compared with the available experimental results in terms of radial Velocity, tangential Velocity and flow angle. In general, the predicted results show a reasonable agreement with the experimental data. A steady state simulation and analysis regarding the interaction between the impeller and various vaned diffusers is carried out. For the interface between the rotational impeller outlet and the stationary vaned diffuser inlet, the stage averaging condition is used. A detailed comparison between the predicted and the available experimental data is performed in terms of static pressure rise, total pressure ratio, choking mass flow and efficiency characteristics, and very good agreement is accomplished. In addition, detailed flow distributions are compared, assessed and critically analysed, regarding different number of diffuser vanes, rotational speed, gap between the leading edge of the vaned diffuser and impeller tip, mass flow rate. Emphasis is focused on the steady state study of the effect of the number of diffuser vanes on the stage operating range. Further more, unsteady simulation and analysis regarding the interactions between backswept impeller and downstream vaned diffusers is carried out. In the unsteady simulation, a geometry scaling method is used to modify the diffuser geometry to the nearest integer pitch ratio while keeping the throat area, flow direction and area ratio unchanged in order to deal with the unequal pitch ratio problems which exist in the unsteady simulation. The unsteady investigation was undertaken regarding different number of diffuser vanes, rotational speed, gap between the leading edge of the vaned diffuser and impeller tip, mass flow rate and impeller tip clearance. The detailed interactions at different conditions are compared, assessed and analysed. The studies focus on the analyses of the effect of the different interactions on the stage operating range, peak efficiency, total pressure ratio, level of unsteadiness, flow structures, flow angle or incidence angle, etc. In addition, the' predicted results are compared with available experimental data and a quite good agreement is achieved although the geometry is scaled. On the other hand, a detailed investigation on the differences between the time averaged unsteady simulation results and steady simulation results was performed at different conditions. The comparisons were carried out regarding static pressure, total pressure, speed, flow angle (or incidence angle) and isentropic efficiency. The investigation confirms that unsteady simulation is still quite important, since some of the steady state simulation results are still not similar to the time averaged ones. Designers should take into account the influence of the unsteadiness on the flow fields when they employ the steady state model in the design process.

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Усенко, Наталія Миколаївна, Наталия Николаевна Усенко, Nataliia Mykolaivna Usenko i O. Shcherbacov. "Multi-objective optimization of a 3D vaneless diffuser". Thesis, Видавництво СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/17187.

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Kumlu, Armagan. "CFD INVESTIGATION OF IMPELLER DIFFUSER INTERACTION EFFECTS ON RADIAL COMPRESSOR STAGE". Thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157534.

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The effects of impeller-diffuser interaction are investigated through numerically simulating the modified wedge vane profiles. Steady and time-accurate, 3D- viscous RANSsolver is used to perform flow field computations. The original design is modified to obtain better aerodynamic performance. Five morechanges are made to the leading edge profile of the new design, in order to assess different degrees of unsteadiness. These changes show that their contribution on stageefficiency is rather minor, while they have a huge reduction on blade loadings. Moreover, it is shown that the shorter radial distance of vaneless space does not necessarilymean an increased loading thanks to the eliminating in-phase fluctuations on pressureand suction sides. It is found that the impeller reacts to the upstream static pressure disturbance, whichis caused by the applied geometry change and its resultant flow field in the wedge diffuser, but not to the radial location of a certain profile. In addition, the results indicatethat the wedge diffuser aerodynamic performance is driven by time-averaged flow fieldbehaviour.

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Ahmed, Noukhez. "Performance evaluation and optimisation of vaneless diffuser of various shapes for a centrifugal compressor". Thesis, University of Huddersfield, 2018. http://eprints.hud.ac.uk/id/eprint/34684/.

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In recent years, diesel engines with reduced emissions and low fuel consumption have been developed worldwide for the purpose of environmental protection and energy conservation. Turbochargers are playing an important role in these modern engines by providing power boost to the engine. A turbocharger comprises of three major parts i.e. the turbine stage, the bearing housing and the compressor stage. Turbocharger designers are continuously seeking for compact stage designs, while maintaining the stage performance. A turbocharger’s compressor stage comprises of various parts i.e. inlet, impeller, diffuser and volute. The diffuser is an important section of the turbocharger compressor stage that plays a key role in increasing the isentropic efficiency of the stage. The diffuser converts the kinetic energy imparted to the flow by the impeller, into static pressure rise, which inturn increases the isentropic efficiency of the stage. The shape of a diffuser is conventionally simple in design. Modifications to the diffuser geometry can lead to higher efficiencies and compact designs of the compressor stage. The present study focuses on the use of advanced computational techniques, such as Computational Fluid Dynamics (CFD), to analyse the effects of diffuser modifications on the local flow features, and the global performance parameters. A baseline diffuser configuration, consisting of a parallel wall diffuser, is numerically analysed to establish the accuracy of CFD based predictions. Various diffusers’ geometrical configurations have been analysed in the present study, both qualitatively and quantitatively. These geometrical configurations cover a wide range, such as diverging, tilting and curving of the diffuser walls. These parametric investigations aid to improve the compressor stage performance and make it more compact. The first aim of the study is to quantify the increase in the stage performance by diverging the straight wall vaneless diffuser passage. This is carried out by diverging the shroud wall (i.e. increasing the outlet-to-inlet width ratio) and varying the location of the divergence point on the shroud wall. The results obtained depict that the effect of increasing the diffuser’s outlet-to-inlet width ratio is dominant in comparison with the location of the wall divergence point. Moreover, increase in diffuser’s outlet-to-inlet width ratio increases the downstream area ratio of the diffuser, causing the flow to separate and creating flow recirculation near the hub wall. This creates restriction to the flow and causes air blockage. Furthermore, shifting the wall divergence point towards the outlet of the diffuser relocates the flow separation point closer to the diffuser exit. The second aim of this study is to analyse the effects of tilted diffuser walls on the flow variables within the compressor stage of the turbocharger. Tilting diffuser walls provides an increased streamwise length to the flow. Furthermore, divergence is applied to the diffuser hub wall in order to increase the outlet-to-inlet width ratio. This makes the turbocharger compressor stage compact in design, while maintaining the stage performance, which is the current requirement of the automotive sector. Design of Experiments, using Taguchi method, has been incorporated in this study to define the scope of the numerical work. The results obtained show that the diffuser with both titled and diverged walls together, performs optimally as compared to the other configurations considered. The third aim of this study is to use curved diffuser walls in order to make the design more compact. Divergence to the hub wall is also applied to enhance the performance of the compressor stage. Various configurations of curvilinear diffuser walls have been considered for numerical analysis. The local flow field analysis has been carried out, quantifying the effects of the geometrical parameters on the stage performance. The results depict that a curved diffuser model reduces the losses within the diffuser passage, but there is negligible effect on the stage efficiency. However, when the divergence is applied to the hub wall of the curved diffuser, there is significant increase in the stage efficiency. Based on these investigations, a turbocharger’s compressor stage can be designed for a compact design and optimal efficiency.

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Gongol, Jakub. "Návrh malého proudového motoru do 1kN tahu". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230963.

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This work will be focused on issue of a jet engine. The thesis will be divided into search retrieval part and computational part. In the search retrieval part it will focus on different configurations of jet engines as well as areas of their use. The main part of the thesis will however focus on a calculations where a turbine, compressor and an exhaust nozzle will be designed in order to give a thrust of approximately 1kN. Next step will be determination of an engine charcteristic that will give us a preview on how the engine performance will look like in off-design modes.

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BILIOTTI, DAVIDE. "Characterization of vaneless diffuser rotating stall on centrifugal compressors for industrial applications". Doctoral thesis, 2014. http://hdl.handle.net/2158/867715.

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In this study, a systematic approach both to characterize the industrial rotating stall and to predict the behavior of the machine in case of operation in stall conditions was developed and validated. The attention was mainly focused on the vaneless diffuser rotating stall, which generally occurs as a result of a separation of boundary layer and consequently a reverse flow by analyzing the phenomenon from both a numerical and an experimental point of view.

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Reddy, D. Narasimha. "Some studies on swirling compressible flow through a vaneless radial diffuser". Thesis, 1986. http://localhost:8080/iit/handle/2074/4921.

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Książki na temat "Vaneless diffusers"

Center, Lewis Research, red. A three-dimensional axisymmetric calculation procedure for turbulent flows in a radial vaneless diffuser. Cleveland, Ohio: Lewis Research Center, 1985.

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Center, Lewis Research, red. A three-dimensional axisymmetric calculation procedure for turbulent flows in a radial vaneless diffuser. Cleveland, Ohio: Lewis Research Center, 1985.

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Center, Lewis Research, red. A three-dimensional axisymmetric calculation procedure for turbulent flows in a radial vaneless diffuser. Cleveland, Ohio: Lewis Research Center, 1985.

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Center, Lewis Research, red. A three-dimensional axisymmetric calculation procedure for turbulent flows in a radial vaneless diffuser. Cleveland, Ohio: Lewis Research Center, 1985.

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Moore, F. K. Theory of finite disturbances in a centrifuglal compression system with a vaneless radial diffuser. [Washington, D.C.]: National Aeronautics and Space Administration, 1990.

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A three-dimensional axisymmetric calculation procedure for turbulent flows in a radial vaneless diffuser. Cleveland, Ohio: Lewis Research Center, 1985.

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A three-dimensional axisymmetric calculation procedure for turbulent flows in a radial vaneless diffuser. Cleveland, Ohio: Lewis Research Center, 1985.

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Części książek na temat "Vaneless diffusers"

Solomon, Gnanadurai Ravikumar, R. Rahul, R. Balaji i Ashish Selokar. "Fluid Flow Analysis of a Rotating Vaneless Diffuser Using CFD". W Lecture Notes in Mechanical Engineering, 1121–37. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-2794-1_97.

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Frolov, Alexey, Rudolf Izmaylov i Denis Voroshnin. "Flow Field Numerical Research in a Low-Pressure Centrifugal Compressor with Vaneless Diffuser". W Mathematics in Industry, 203–10. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05365-3_28.

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Zhou, Banglun, Antoine Dazin, Annie-Claude Bayeul-Lainé, Jianping Yuan, Yaguang Heng, Patrick Dupont i Najib Ouarzazi. "“Low Cost” Approaches for the Prediction of Rotating Instabilities in the Vaneless Diffuser of a Radial Flow Pump". W Advances in Hydroinformatics, 965–79. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7218-5_68.

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Kalinkevych, M., O. Shcherbakov, O. Gusak i V. Ihnatenko. "Investigation of the gas flow in the vaneless diffusers of the centrifugal compressors". W 7th International Conference on Compressors and their Systems 2011, 51–60. Elsevier, 2011. http://dx.doi.org/10.1533/9780857095350.2.51.

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"Vaneless Diffuser Design". W Centrifugal Compressors: A Strategy for Aerodynamic Design and Analysis, 159–66. ASME Press, 2000. http://dx.doi.org/10.1115/1.800938_ch8.

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Kalinkevych, M., O. Shcherbakov i V. Ihnatenko. "Investigation of gas flow with injection in vaneless diffuser of centrifugal compressor". W 8th International Conference on Compressors and their Systems, 501–10. Elsevier, 2013. http://dx.doi.org/10.1533/9781782421702.9.501.

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Ubaldi, M., P. Zunino i A. Ghiglione. "Detailed flow measurements within the impeller and the vaneless diffuser of a centrifugal turbomachine". W Engineering Turbulence Modelling and Experiments, 753–62. Elsevier, 1996. http://dx.doi.org/10.1016/b978-0-444-82463-9.50078-2.

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Jaatinen, A., A. Grönman i T. Turunen-Saaresti. "Effect of diffuser width and tip clearance on the static pressure distributions in a vaneless diffuser of a high-speed centrifugal compressor". W 10th International Conference on Turbochargers and Turbocharging, 319–24. Elsevier, 2012. http://dx.doi.org/10.1533/9780857096135.6.319.

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Streszczenia konferencji na temat "Vaneless diffusers"

Niizeki, Yoshiki, i Toshimichi Sakai. "A Study of Radially Curved Mixed-Flow Vaneless Diffusers". W ASME 1986 International Gas Turbine Conference and Exhibit. American Society of Mechanical Engineers, 1986. http://dx.doi.org/10.1115/86-gt-89.

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The flow pattern and performance of radially-curved mixed-flow vaneless diffusers were examined. From the experimental results the correlation between the inlet flow angle, the radius of curvature of the radially curved test section and diffuser performance was clarified. Favorable inner flow with higher diffuser performance were obtained in the case of diffusers having small pressure gradient normal to the diffuser walls. From this concept, a method to give an optimum configuration of the radially curved diffuser was established.

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De Bellis, Fabio, Angelo Grimaldi, Dante Tommaso Rubino, Riccardo Amirante i Elia Distaso. "Accurate Radial Vaneless Diffuser 1D Model". W ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25232.

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A simplified one dimensional model for the performance estimation of vaneless radial diffusers is presented. The starting point of such a model is that angular momentum losses occurring in vaneless diffusers are usually neglected in the most common turbomachinery textbooks: it is assumed that the angular momentum is conserved inside a vaneless diffuser, although a non-isentropic pressure transformation is considered at the same time. This means that fluid-dynamic losses are taken into account only for what concerns pressure recovery, whereas the evaluation of the outlet tangential velocity incoherently follows an ideal behavior. Several attempts were presented in the past in order to consider the loss of angular momentum, mainly solving a full set of differential equations based on the various developments of the initial work by Stanitz. However, such formulations are significantly more complex and are based on two empirical or calibration coefficients (skin friction coefficient and dissipation or turbulent mixing loss coefficient) which need to be properly assessed. In the present paper, a 1D model for diffuser losses computation is derived considering a single loss coefficient and without the need of solving a set of differential equations. The model has been validated against massive industrial experimental campaigns, in which several diffuser geometries and operating conditions have been considered. The obtained results confirm the reliability of the proposed approach, able to predict the diffuser performance with negligible drop of accuracy in comparison with more sophisticated techniques. Both preliminary industrial designs and experimental evaluations of the diffusers may benefit from the proposed model.

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Jaatinen, Ahti, Aki-Pekka Gro¨nman, Teemu Turunen-Saaresti i Jari Backman. "Experimental Study of Vaned Diffusers in Centrifugal Compressor". W ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22883.

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Improving the performance of a centrifugal compressor can lead to decreased energy consumption in industry. Vaned diffusers are known to narrow the operating range but increase the peak efficiency compared to vaneless diffusers. In this study, three vaned diffusers and one vaneless diffuser are studied experimentally to improve compressor performance. Attention is paid to the operating range and performance of the diffuser, specially close to stall, and therefore the vaned diffusers are designed to have large negative incidence (−8°) at the design conditions. Different vane numbers and vane turnings are used. Compressor performance maps are measured at different rotating speeds and diffuser flow fields at the design rotating speed. The results show that the vaned diffusers make the diffuser outlet flow field more uniform than the vaneless one. The peak efficiency of the vaned diffusers occur at lower mass flows, and the efficiency is also higher at the design operation point with the vaned diffusers. In general, the vaned diffusers are better at lower mass flows, but stall earlier.

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Dou, Huashu. "Investigation of the Prediction of Losses in Radial Vaneless Diffusers". W ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-323.

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The non-dimensional width B and the inlet flow angle αi are the important parameters influencing the losses and the stability of radial vaneless diffusers. Their effects on diffuser losses are analyzed in this paper. The portions of the various flow losses change with the variation of non-dimensional width parameter B and flow angle αi. In a diffuser with small width B, the loss is primarily due to wall friction loss. In a diffuser with large B, the wall friction loss becomes a small part of the total loss, especially when αi is large. Comparison with experimental data shows that it is better to calculate the performance parameters of radial vaneless diffusers by using Dou’s method than by Senoo’s method in the design of centrifugal compressors. Senoo’s method is found to be only suitable for the conditions of small B values because it calculates simply the wall friction loss and the secondary flow loss and neglects diffusion loss.

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Harada, Hideomi, i Masanori Goto. "Numerical and Experimental Studies of Single and Tandem Low-Solidity Cascade Diffusers in a Centrifugal Compressor". W ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-108.

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In order to experimentally determine the performance characteristics of low-solidity cascade diffusers, three kinds of diffusers, a vaneless diffuser, a single and a tandem low-solidity cascade diffuser were attached to a medium specific speed centrifugal compressor stage and tested on a closed-loop test stand. The three-dimensional incompressible viscous flow analysis method, which had recently been established in our laboratory, was used to calculate the internal flow conditions inside of these diffusers. Both the single and tandem low-solidity cascade diffusers performed better than the vaneless diffuser. In particular, the tandem low-solidity cascade diffuser showed an increase in static pressure recovery coefficient of greater than 15% at the design point, and an increase greater than 40% at the lower flow rate, as compared with the pressure recovery of a vaneless diffuser. The total-to-static overall compressor stage efficiency was improved by 4% to 10% from 100% to 70% flow rate by using the tandem diffuser. The measured blade to blade static pressure distribution inside the low-solidity cascade diffusers was compared with the numerical results obtained via 3D viscous incompressible flow analysis, and the authors found that the static pressure recovery was qualitatively well predicted by this flow analysis method.

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Epple, Philipp, Mihai Miclea, Caslav Ilic i Antonio Delgado. "Combined Impeller-Diffuser Design and the Influence of Slotted Guide Vanes on the Performance of Radial Diffusers". W ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11260.

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Radial diffusers are devices to increase the static pressure of a radial impeller-diffuser-unit (IDU) and in many cases also its efficiency. A new design method for the coupled Impeller-Diffuser-Layout is proposed. This new design method is presented and the resulting theoretical differences of the vaned and vaneless diffusers are shown. It is known, also, that at high flow rates, the vaned diffusers will choke, i.e. the maximum flow rate of an IDU will be much less as the one of the impeller alone or an IDU with vaneless diffuser. In order to avoid the flow rate decrease in the vaned diffuser due to this blockage or choking, a new kind of diffuser is proposed: the slotted diffuser. The theoretical principles of chocking and the solution with the slotted diffusers are explained. In order to have an in depth understanding of its working principle, three IDU are numerically examinated: with vaneless diffuser, regular vaned diffuser and the new slotted diffuser. In general the slotted diffuser delivers approximately the same pressure and efficiency but a substantial higher flow rate than the vaned diffuser. The vaneless diffuser has the highest flow rate, but the lowest pressure. An in detail analysis of the gap losses between the exit of the impeller and the entry of the vaned regular and slotted diffusers is presented, unrevealing an major loss source in vaned IDU. Flow patterns of the different diffuser types are shown illustrating in a clear manner the working principle of these diffusers and their respective advantages and disadvantages. Finally, in order to validate the theoretical and numerical results, prototypes were built and measurements performed at a norm test rig according to DIN 24 163. Pictures of the prototypes as well as of the test rig are shown. The experimental results are in good agreement with the predictions of the numerical simulations confirming the theoretical and numerical investigations.

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Engeda, Abraham. "Comparative Rotating Stall and Surge Characteristic of a Centrifugal Compressor With Three Different Types of Diffusers". W ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-245.

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The diffuser system of a centrifugal compressor comes basically in two general categories either as vaneless or vaned diffuser. Vaned diffusers can further be subdivided into two depending on channel geometry as straight channel or curved channel, or depending on solidity. Three different diffuser types: a vaneless, conventional vaned and a low solidity vaned were tested in the present study. All diffusers were tested downstream of the same impeller. All the diffusers had the same diffuser exit radius to impeller tip radius ratio. The influence of each type of diffuser on the performance and stall characteristics of the inducer and impeller as a whole was studied. In addition, diffuser stall characteristics of each type diffuser were also studied. The type of diffuser had no significant effect on inducer and impeller stall. The inducer was more stable with the conventional vaned diffuser configuration. Rotating Stall was detected with the vaneless diffuser configuration at the onset of surge. Four stall cells rotated in the same direction as the impeller at 122 Hz. Numerous works have been documented on rotating stall and surge for centrifugal compressors. Prediction of the inception of rotating stall and surge for a specific geometry and operation is not yet fully possible. Therefore, experimental results and correlations are still of great importance.

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Kinoshita, Yoshifumi, i Takashi Matsumura. "Direct Numerical Simulation of Rotating Stall and Stall Induced in Centrifugal Vaneless Diffusers". W ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0452.

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A direct numerical simulation (DNS) method is proposed to evaluate the general incompressible flow behaviors in the centrifugal vaneless diffusers. This method is then applied to three kinds of centrifugal vaneless diffusers. In this way, it is confirmed that the flow pattern predicted based on the present DNS method agrees with experiments not only under the rotating stall condition but also under the diffuser stall condition. In addition, the predictions for rotating stall limit are shown to agree with the authors’ previously proposed criterion for rotating stall limit. Finally, it is clarified both experimentally and numerically that the authors’ previously proposed criterion for diffuser stall is correct; that is, when the zone of inward swirl flow reaches the exit of the diffuser, diffuser stall begins.

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Engeda, Abraham. "Design and Investigation of Four Low Solidity Vaned Diffusers to Assess the Effect of Solidity and Vane Number". W ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-252.

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As part of a continued effort to understand the design and performance of Low Solidity Vaned Diffusers (LSVD), four new LSVDs have been designed and tested. A centrifugal compressor stage usually consists of the inlet, impeller, diffuser and collector systems. Even though the individual components of the compressor are capable of achieving high efficiency, it is the efficiency of the whole stage that is of great importance. The diffuser system of a centrifugal compressor comes basically in two general categories either as vaneless or vaned diffuser (excluding pipe diffusers). Vaned diffusers can further be subdivided into two depending on channel geometry as straight channel or curved channel, or depending on solidity. It is currently believed that the LSVD offers a compromise between a vaned and a vaneless diffuser by possessing the virtues of each. This paper discusses the design and experimental investigation of the new four LSVDs. The diffusers had a solidity of 0.9, 0.8, 0.7 and 0.6. These newly designed LSVDs are known as LSVD#5 to LSVD#8.

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Wulf, James B. "Stage Efficiency Effects of Vaneless Diffuser Wall Contours". W ASME 1992 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/92-gt-018.

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The effects of vaneless diffuser wall contour were investigated in a systematic series of laboratory tests. The test stage was investigated in an integral gear compressor operating on a laboratory test stand. The compressor was driven with a variable speed 1500 HP motor. A computer controlled data acquisition and reduction system was used. The 27.94 cm diameter test impeller was operated with vaneless diffusers and volute collectors. Beginning with a substantially parallel wall vaneless diffuser, peak stage adiabatic total to total efficiency was improved from 80.2% to 87.5% and operating range was extended. The interaction between the impeller, diffuser and volute was studied through detailed analysis of intra-stage static pressure data using a jet wake model. The results of data analysis show that wall contour had a small influence on impeller efficiency and that most of the stage performance improvement resulted from improved recovery in the vaneless diffuser.

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