Subsonic Centrifugal Compressor Research Articles

CFD Modeling of Flow Performance inside Subsonic Centrifugal Compressor

Centrifugal Compressors, which offer good flow stability, compact size and high stage pressure ratio, have been widely used in helicopter engines and sometime served as high pressure stage in small turbojet engines. In this paper, a method of developing a CFD model is presented for investigating the flow performance of a subsonic centrifugal compressor. The configuration used for the study is a subsonic centrifugal compressor which has a 60mm diameter impeller. A CFD modeling is carried out to obtain the performance and operational range of the compressor stage. The mesh independence studies were performed to provide confidence in the numerical results at operation speed. Particular emphasis is laid on the flow performance analysis with designed rotational speed of impeller.

A Time-Marching Method for the Calculation of Nonsimilar 3D Boundary Layers on Turbomachinery Blades

A method is presented for the computation of three-dimensional boundary layers on turbomachinery blades. The method is based on a finite difference approach on a body-fitted curvilinear coordinate system, in which the time-dependent 3D boundary layer equations are marched in time until the steady-state solution is found. The method does not employ a similarity law and can therefore be applied to nonsimilar boundary layers. The method not only enables one to compute the skin friction and displacement of the boundary, but also provides information on the sources of entropy generation on the blades. The entropy generation is in fact split into three main components, which correspond to heat conduction, streamwise shear stress, and cross-flow shear stress. By considering each of the components of shear stress, at the design stage considerable insight can be found on the best way of modifying the blade geometry in order to reduce blade losses. The method is validated by comparison with analytical data for a laminar flat plate, experimental results for a helical blade in turbulent flow, and an axial compressor blade. Finally, the method is applied to the prediction of boundary layers on a subsonic centrifugal compressor impeller blade.

Prediction of active control of subsonic centrifugal compressor rotating stall

Prediction of active control of subsonic centrifugal compressor rotating stall

Experimental and Computational Results From the NASA Lewis Low-Speed Centrifugal Impeller at Design and Part-Flow Conditions

The NASA Lewis Low-Speed Centrifugal Compressor (LSCC) has been investigated with laser anemometry and computational analysis at two flow conditions: the design condition as well as a lower mass flow condition. Previously reported experimental and computational results at the design condition are in the literature (Hathaway et al., 1993). In that paper extensive analysis showed that inducer blade boundary layers are centrifuged outward and entrained into the tip clearance flow and hence contribute significantly to the throughflow wake. In this report results are presented for a lower mass flow condition along with further results from the design case. The data set contained herein consists of three-dimensional laser velocimeter results upstream, inside, and downstream of the impeller. In many locations data have been obtained in the blade and endwall boundary layers. The data are presented in the form of throughflow velocity contours as well as secondary flow vectors. The results reported herein illustrate the effects of flow rate on the development of the through flow momentum wake as well as on the secondary flow. The computational results presented confirm the ability of modern computational tools to model the complex flow in a subsonic centrifugal compressor accurately. However, the blade tip shape and tip clearance must be known in order to properly simulate the flow physics. In addition, the ability to predict changes in the throughflow wake, which is largely fed by the tip clearance flow, as the impeller is throttled should give designers much better confidence in using computational tools to improve impeller performance.