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Computational Analysis of the Effect on Centrifugal Compressor Performance by Tapered Wall and Rotating Tapered Wall Vaneless Diffuser
Author(s): Niveditha Porika, Bhamidi V.S.S.S. Prasad
Keywords: Compressor performance, Computational fluid dynamics, Rotating diffuser, Tapered diffuser, Vaneless diffuser
Numerical analysis is performed to increase the rate of diffusion in the centrifugal compressor fitted with the tapered vaneless diffuser. The parameters involved in the present study are the diffuser wall taper angle and diffuser rotational speed. Using ANSYS CFX 17.2 simulations are performed from 1° to 6° tapered vaneless diffuser in the interval of 1°. The simulations are carried out for stationary tapered vaneless diffuser and rotating tapered vaneless diffuser. Performance characteristics such as static pressure recovery coefficient, stagnation pressure loss coefficient, isentropic efficiency, energy coefficient and torque coefficient are plotted to study the performance enhancement in modified geometries with the base model. Pressure, radial velocity, static entropy, and velocity streamlines contours are plotted at design point in each modified diffuser geometry to study the flow within the compressor domain. Of all those cases of stationary tapered diffusers, tapered_SVD_3 showed optimal performance in terms of isentropic efficiency (η), static pressure recovery coefficient (CP) increased by 1.5%, 8.97% and Stagnation pressure loss coefficient (CPOL) decreases by 10.7%. TaperedRVD6 have been shown to be optimal in rotating tapered diffusers, with Static pressure recovery coefficient (CP) increased by 39.77% and isentropic efficiency (η) and stagnation pressure loss coefficient (CP0L) decreases by 2.9%, 32.14% respectively in case of rotating tapered diffuser.