Experimental Investigation of the Flow Field in a Multistage Axial Flow Compressor

Abstract

The nature of the flow field in a three stage axial flow compressor, including a detailed survey at the exit of an embedded stator as well as the overall performance of the compressor is presented and interpreted in this paper. The measurements include area traverse of a miniature five hole probe (1.07 mm dia) downstream of stator 2, radial traverses of a miniature five hole probe at the inlet, downstream of stator 3 and at the exit of the compressor at various circumferential locations, area traverse of a low response thermocouple probe downstream of stator 2, radial traverses of a single sensor hot-wire probe at the inlet, and casing static pressure measurements at various circumferential and axial locations across the compressor at the peak efficiency operating point. Spectral analysis of the hot-wire data reveal the existence of several harmonics of all three rotor blade passing frequencies at the inlet of the compressor. Mean velocity, pressure and total temperature contours as well as secondary flow contours at the exit of the stator 2 are reported and interpreted. Hub clearance flow is shown to eliminate the suction surface corner separation. Secondary flow contours show the migration of fluid particles toward the core of the low pressure regions located near the suction side casing endwall corner. The RMS value of the spatial fluctuations in mean velocity downstream of the second stator (which appear as temporal variations to the subsequent rotor) have been derived and shown to be significant.

Steady and Unsteady Three-Dimensional Flow Field Downstream of an Embedded Stator in a Multistage Axial Flow Compressor: Part 1 — Unsteady Velocity Field

“…The traverse can be axially moved such that area traverses can be conducted downstream of stators 2 and 3 and rotor 3. Lakshminarayana et al, 1994 provide a complete description of the test compressor, associated instrumentation, operating characteristics, blade profile geometries, and area traverse locations. All the measurements reported in this paper were acquired at the peak efficiency (90.65%) operating condition.…”

Stator Exit Flow Fields in the Multistage Environment of an Axial Compressor

“…The present investigation follows the current trend in axial compressor research, with special emphasis • on commercially designed multistage machinery (see Vinnemeier, 1991;Honen et al, 1994;Lakshminarayana et al, 1994 andFoley et al, 1994 for reference) According to the current state of the research program, only stator exit results have been presented, yielding the stage-bystage development of endwall flow fields, the influences of tip clearance geometry, off-design conditions and blade row interactions. Fig.1 shows the cross-sectional view of the four stage axial compressor with measurement planes indicated.…”

Exit Flowfield of an Embedded Stator in a Multistage Axial Flow Compressor

“…Further details of these operating conditions and performance characteristics of this compressor can also be found in Ref. 6. …”

“…The Quick-Basic program was also interfaced with the DAS-50 software to provide computer-controlled probe traversing. A more detailed description of the compressor facility, schematic of the compressor ow path, probe insertion slots, area traverse mechanism, and data acquisition procedures can be found in Lakshminarayana et al 6 Complete area traverses at the exit of stator 2 were obtained using a subminiature probe ve-hole probe in conjunction with the area traverse mechanism. The method of Treaster and Yocum 7 was used to determine the yaw and pitch angles and the total and static pressure of the ow eld from calibration data.…”