Experimental Study of the Flow Field Within a Transonic Axial Compressor Rotor by Laser Velocimetry and Comparison With Through-Flow Calculations

Abstract

The flow field ahead, within, and behind the rotor of a transonic axial compressor designed for a total pressure ratio of 1.51 at a relative tip Mach number of 1.4 has been studied in detail using an advanced laser velocimeter. The tests were carried out at 70 and 100 percent design speed (20,260 rpm) and equivalent mass flows corresponding to the point of maximum isentropic efficiency. The tests yielded quite complete data on the span- and gap-wise velocity profiles, on the three-dimensional shock waves in and outside of the rotor blade channels, and on the blade wakes. Some of the experimental results will be submitted, discussed, and compared to corresponding analytical data of a through-flow calculation. The comparison reveals considerable discrepancies inside the blade row between the two-dimensional calculation and the experiments primarily due to the loss and deviation correlations used, as well as to the distribution of losses and flow angles inside the blade channels.

Three-Dimensional Shock Structures for Transonic/Supersonic Compressor Rotors

“…A similar investigation is reported in Ref. 6. These two investigations appear to contain the only readily available results of this type.…”

“…6 "It is recognized that the velocity jump across the normal shock does not follow the classical normal shock relations." 5 "Considered in two dimensional terms this front would represent a normal shock.…”

Review—Computational Methods for Internal Flows With Emphasis on Turbomachinery

“…Secondorder isoparametric quadrilateral elements were used to permit accurate simulation of blade curvature. Results compared favorably with the LDV data obtained by DFVLR in Germany [65]. In 1980 Hirsch [66] presented an iterative analysis for centrifugal compressors, and applied it to the radial compressor mapped with LDV by Eckardt [67].…”

Efficient Laser Anemometer for Intra-Rotor Flow Mapping in Turbomachinery

“…Several approaches to laser anemometry have been applied to turbomachine ry. Among these are the fringe-type anemometer (sometimes called 3 laser Doppler velocimeter) (2,3) and the time-of-flight anemometer (4)(5)(6).…”

“…In each of the systems described in (2,(4)(5)(6), the laser was time-gated so that velocity measurements were accepted only during a small fraction of each revolution of the rotor. The reason fur this is as follows.…”