摘要：According to the requirements of a solar dish-Brayton system,a centrifugal compressor stage with a minimum total pressure ratio of 5,an adiabatic efficiency above 75% and a surge margin more than 12% needs to be designed.A single stage,which consists of impeller,radial vaned diffuser,90° crossover and two rows of axial stators,was chosen to satisfy this *** achieve the stage performance,an impeller with a 6:1 total pressure ratio and an adiabatic efficiency of 90% was designed and its preliminary geometry came from an in-house one-dimensional *** vaned diffuser was applied downstream of the *** rows of axial stators after 90° crossover were added to guide the flow into axial *** jet-wake flow,shockwave and boundary layer separation coexisted in the impeller-diffuser region,optimization on the radius ratio of radial diffuser vane inlet to impeller exit,diffuser vane inlet blade angle and number of diffuser vanes was carried out at design ***,an optimized centrifugal compressor stage fulfilled the high expectations and presented proper *** simulation showed that at design point the stage adiabatic efficiency was 79.93% and the total pressure ratio was *** surge margin was 15%.The performance map including 80%,90% and 100% design speed was also presented.

摘要：In order to establish the design methodology of an ultra micro centrifugal compressor, which is the most important component of an ultra micro gas turbine unit, a 10 times size of the final target compressor （impeller outer diameter 40 mm, corrected rotational speed 220,000 r/min） was designed. The problems to be solved for downsizing were examined and a 2-dimensional impeller was chosen as the first model due to its productivity. The conventional 1D prediction method and CFD were used. The prototyped compressor was tested by using cold air at the reduced speed of 110,000 r/min. Following to the 10 times model, a 5 times size of the final target model having fully 3-dimensional shape （impeller outer diameter 20mm, corrected rotational speed 500,000 r/min） was designed and tested by using hot gas at the reduced speed of 250,000 r/min.

摘要：Three vaned diffusers, designed to have high negative incidence (-8°) at the design operating point, are studied experimentally. The overall performance (efficiency and pressure ratio) are measured at three rotational speeds, and flow angles before and after the diffuser are measured at the design rotational speed and with three mass flow rates. The results are compared to corresponding results of the original vaneless diffuser design. Attention is paid to the performance at lower mass flows than the design mass flow. The results show that it is possible to improve the performance at mass flows lower than the design mass flow with a vaned diffuser designed with high negative incidence. However, with the vaned diffusers, the compressor still stalls at higher mass flow rates than with the vaneless one. The flow angle distributions after the diffuser are more uniform with the vaned diffusers.

摘要：Very high flow coefficient centrifugal compressor stages are mostly performance of this type of stages is critical to the entire centrifugal applied as the first stages of multistage compressors. The compressors, but surprisingly little related information is available in the open literature. A centrifugal compressor with high inlet flow coefficient of 0.2, presenting a narrow operating range and unstable running situation even at design speed during the test, is investigated here. To reveal flow details in this centrifugal compressor, numerical simulations have been carried out and indicate that excessive impeller flow diffusion results in the poor performance of this centrifugal compressor. With the same inlet flow coefficient, six redesign cases coming from an in-house one-dimensional analysis program are proposed together with impeller trimming and equal flow area design method for corresponding vaneless diffuser. Performance comparison among these redesign centrifugal compressors is presented and the most suitable one is recommended for test in the future. In addition, three redesign cases with lower inlet flow coefficient developed by means of flow trimming are shown in the end to satisfy potential application areas. Finally, the results in this study can provide valuable reference information for multistage centrifugal compressor design.

摘要：This paper presents the design of a centrifugal compressor for high-speed *** main focus of the research is to develop a centrifugal compressor with improved aerodynamic *** a meridional frame has a significant effect on overall performance of the compressor,special attention has been paid to the end wall *** shroud profile is design with bezier curve and hub profile with circular arc *** blade angle distribution has been arranged in a manner that it merges with single value at impeller *** rake angle is positive at leading edge and negative at trailing edge with identical ***,three-dimensional straight line element approach has been used for this design for better *** verification of the aerodynamic performance has been carried out using CFD software with consideration of a single blade passage and vaneless *** result has been compared with matching size aftermarket compressor stage gas stand *** compressor stage with Trim 55 provides 34%increase in choke flow at 210000 RPM as compared to gas stand data with 87%peak stage efficiency at 110000 *** addition,new surge margin improvement technique has been proposed by means of diffuser *** technique provides an average of 16%improvement in surge margin compared to standard diffuser stage with 55 trim compressor *** mechanical integrity has been validated at maximum RPM with the aluminum alloy 2014-T6 as a fabrication material.

摘要：Starting from the classical centrifugal compressor, cone shaped in meridional cross section, two modifications are considered on the basis of results from 2D and 3D flow models. The first modification is the change of the meridional cross section to hyperbolically shaped channel. The second modification, proposed on the basis of 2D axisymmetric solution, concerns the shape of blading. On the strength of this solution the blades are formed as 3D shaped blades, coinciding with the recent tendency in 3D designs. Two aims were considered for the change of meridional compressor shape. The first was to remove the separation zone which appears as the flow turns from axial to radial direction. The second aim is to uniformize the flow at exit of impeller. These two goals were considered within the frame of 2D axisymmetric model. Replacing the cone shaped compressor by a hyperbolically shaped one, the separation at the corner was removed. The disc and shroud shape of the compressor was chosen in the way which satisfies the condition of most uniform flow at the compressor exit. The uniformity of exit flow from the rotor can be considered as the factor which influences the performance of the diffuser following the rotor. In the 2D model a family of stream surfaces of S1 type is given in order to find S2 surfaces which may be identified with the midblade surfaces of compressor blading. A computation of 3D type has been performed in order to establish the relations between 2D and 3D models in the calculation of flow parameters. In the presented example the 2D model appears as the inverse model which leads to 3D shape of blading whereas the 3D model has been used for the direct solution. In the presented example the confrontation of two models, 2D and 3D, leads to a better understanding of the application of these models to the design procedure.

摘要：Multidisciplinary design optimization （MDO） is widely employed to enhance turbomachinery compo- nents efficiency. The aim of this work is to describe a complete tool for the aero-mechanical design of a radial in- flow turbine and a centrifugal compressor. The high rotational speed of such machines and the high exhaust gas temperature （only for the turbine） expose blades to really high stresses and therefore the aerodynamics design has to be coupled with the mechanical one through an integrated procedure. The described approach employs a fuUy 3D Reynolds Averaged Navier-Stokes （RANS） solver for the aerodynamics and an open source Finite Element Analysis （FEA） solver for the mechanical integrity assessment. Due to the high computational cost of both these two solvers, a meta model, such as an artificial neural network （ANN）, is used to speed up the optimization design process. The interaction between two codes, the mesh genera- tion and the post processing of the results are achieved via in-house developed scripting modules. The obtained results are widely presented and discussed.

摘要：High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. R is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.

摘要：This paper discusses the influence of various volute designs on volute overall performance for a certain centrifu- gal compressor with both vaned and vaneless diffuser. Firstly, based on a free vortex flow pattern and the assumption of a circumferentially uniform flow at the design condition, a corrected method for volute design is adopted. By means of this method, corresponding to five geometric parameters affecting the volute overall performance, ten volute cases are designed. Secondly, the numerical simulation is employed and the detailed flow field and losses in different volutes with different geometric parameters are analyzed. The numerical investigation reveals that in all of the five geometric parameters, the radial location of the cross-section has the strongest influence on the performance of the volute. The non-uniform volute inlet formed by the upward vaned diffuser outlet flow is another important factor. Finally a relatively better value of D1/D2 is concluded.

摘要：In order to improve the performances of an 11 cm-diameter turbine engine,this article suggests to substitute a new-style micro diffuser redesigned based on a new concept for the traditional diffuser having poor performances. The new diffuser comprises integral blades and splitters,which are taken for a series of ducts in designing. This article investigates the effects of the cross-section area distribution along the flow path on the redesigned diffuser＇s performances. Having furnished with the new diffuser in place of the original vaned one,the 11 cm-diameter prototype engine is tested on the rig for its performances. CFD and experiments have shown that the improved diffuser with the unchanged original size has gained excellent performance parameters of pressure coefficient over 0.65 and total pressure recovery coefficient over 0.9. Equipped with the redesigned micro diffuser,the engine increases the thrust by 11% and decreases the specific fuel consumption by 9%.