Investigations of the Flow Through a High Pressure Ratio Centrifugal Impeller

Abstract

In an industrial research project of German and Swiss Turbo Compressor manufacturers a high pressure ratio centrifugal impeller was designed and investigated. Performance measurements and extensive laser measurements (L2F) of the flow field upstream, along the blade passage and downstream of the impeller have been carried out. In addition to that, 3D calculations have been performed, mainly for the design point. Results have been presented by Krain et al., 1995 and 1998, Eisenlohr et al., 1998 and Hah et al.,1999. During the design period of this impeller a radial blade at the inlet region was mandatory to avoid a rub at the shroud due to stress reasons. The measurements and the 3D calculations performed later, however, showed a flow separation at the hub near the leading edge due to too high incidence. Additionally a rather large exit width and a high shroud curvature near the exit caused a flow separation near the exit, which is enlarged by the radially transported wake of the already addressed hub separation. Changes to the hub blade angle distribution to reduce the hub incidence and an adaptation of the shroud blade angle distribution for the same impeller mass-flow at the design point were investigated by means of 3D calculations first with the same contours at hub and shroud; this was followed by calculations with a major change of the shroud contour including an exit width change with a minor variation of the hub contour. These calculations showed encouraging results; some of them will be presented in conjunction with the geometry data of the original impeller design.

Mechanisms of Sweep on the Performance of Transonic Centrifugal Compressor Impellers

“…Its geometry specification has been given by Appl. Sci. 2017, 7, 1081 8 of 22 Eisenlohr et al [36] and its measurement results have been provided by Krain et al [37]. The compared pressure curves are at 60%, 70% and 80% of design speeds, where the operating pressure ratios are similar to the investigated case.…”

“…To further validate the numerical method for predicting performances and detailed flow fields of impellers with vaneless diffusers, the open transonic centrifugal compressor SRV2-O has been investigated applying the same numerical method. Its geometry specification has been given by Eisenlohr et al [36] and its measurement results have been provided by Krain et al [37]. The compared pressure curves are at 60%, 70% and 80% of design speeds, where the operating pressure ratios are similar to the investigated case.…”

An aerodynamic design and numerical investigation of transonic centrifugal compressor stage

“…It is generally said that extra losses are generated by interaction of the shock wave and the boundary layers on the blade surface. On the other hand, the flow separation very often appears inside high-pressure-ratio impeller, resulting in significant inhomogeneous rotor exit flow [4][5][6].…”

Multipoint and Multiobjective Optimization of a Centrifugal Compressor Impeller Based on Genetic Algorithm

“…The detection process continues until a preset minimum pressure rise is reached, and the last steady point is regarded as the last stable point before surge. [21,22]. The surge detection validation is carried out by the comparison of surge line between CFD prediction and experimental results of the SRV2AB impeller with vaneless diffuser, which serves as the baseline for the subsequent optimization.…”