Measurement of Tip-Clearance Flow in a Multi-Stage, Axial Flow Compressor

Abstract

Detailed measurements using pneumatic probe traverses, blade static pressure tappings and laser anemometry are made in the third stage of a large scale, low speed, four stage, axial flow, research compressor. Inlet conditions show well ordered ‘two dimensional’ flow from approximately 40 to 85% annulus span. Outside of this region, reduced total pressure due to upstream leakage losses aod endwall effects results in high incidence to the following blade row. As a result, peak suction surface static pressure moves forward along the blade chord for both the huh and tip of stators and rotors. At the blade tip however, the peak suction pressure is maintained with chord due to radial flow on the suction surface being entrained into the tip leakage jet. The extent of rotor chord for which this ‘entrainment’ occurs increases with increasing rotor tip clearance gap. The leakage jet from both stators and rotors is seen to ‘roll up’ into a vortex downstream of their respective blade rows.

Axial Compressor Stage Analysis Through a Multi-Block 3-D Navier-Stokes Solution Method

“…Figure 14 illustrates the ; distributions along the blade at hub, midspan and tip. Tfie t/c=12% curves can be qualitatively compared to the corresponding distributions of Foley and Ivey (1994) which are not repeated here. The comparison is only qualitative for the same as in the rotor case reasons.…”

Characteristics of Tip-Clearance Flows of a Compressor Cascade and a Propulsion Pump

“…Recent studies of tip-leakage flow have involved various turbomachinery configurations, including linear cascades, compressors, turbines and pumps. Experimental studies of tip-gap flows in cascades have been reported by Kang andHirsch (1989, 1993) and Watanabe et al (1995), while Lakshminarayana et al (1986), Inoue et al (1986), Suder and Celestina (1994), and Foley and Ivey (1994), have conducted measurements in compressors. Tip-gap flows in turbines have been studied experimentally by Chan et al (1994), Yamamoto et al (1994), andDeCecco et al (1995) while pump flow experiments have been reported by Graham (1986) and Zierke et al (1994).…”