An experimental investigation of a centrifugal compressor with hub vane diffusers

Abstract

The present investigation reports results of experimental studies on a centrifugal compressor equipped with hub vane diffusers. The diffuser vane height ( h/b) is varied as follows: 0 (vaneless), 0.2, 0.3, 0.4 and 1 (vane). The experiments were carried out on a low specific speed centrifugal compressor with a radial tipped impeller with an inducer at the inlet. The measurements consist of determining performance characteristics, measuring static pressures on the hub and shroud and flow traverses with a precalibrated cobra probe at the diffuser exit over one passage at five flow coefficients, viz. φ = 0.23 (near surge), 0.34 (near peak pressure rise), 0.45, 0.60 and 0.75 (near maximum flow). The peak energy coefficient is maximum for the hub vane diffuser with an h/b ratio of 0.2. The hub vane diffusers have a wider operating range than the vane diffuser. At high flow coefficients, the static pressure rise is substantially low at the throat region of the vane diffuser as the incidence on to the vane leading edge is very high. The mass averaged static pressure coefficient is high in the low-volume range for the hub vane diffuser of h/b = 0.3, but in the high-volume range it is high for the vaneless diffuser.

Performance and wall static pressure measurements on centrifugal compressor diffusers

“…The speed of the compressor can be maintained constant at §1 r/min. The compressor was earlier used for investigations on partial vane diffusers [2].…”

The Effect of Half Vane Diffuser on the Noise Generated from a Centrifugal Fan

“…During the past years, some investigations have been carried out to study the half vane diffuser in centrifugal compressors. The results showed that this diffuser could improve the stage performance 8–10 . Yoshinaga et al 8 proposed a diffuser with half vanes in a centrifugal compressor and the test result showed that the pressure recovery of this diffuser at distorted inlet flow is considerably improved.…”

Numerical Study of the Improvement in Stability and Performance by Use of a Partial Vaned Diffuser for a Centrifugal Compressor Stage

“…In contrast, Liu et al [7] found that a hub-side vaned diffuser has higher pressure recovery and efficiency than a vaneless diffuser and has a wider operating range compared with a traditional vaned diffuser. Sitaram et al [8] showed that a hub-side vaned diffuser has a higher energy coefficient and a wider operating range under a certain vane height. The experimental and simulation investigations by Ohta et al [9] indicated that the tapered vaned diffuser could reduce noise and enlarge the stable operating ranges by vortex control.…”