A LES investigation of off-design performance of a centrifugal pump with variable-geometry diffuser

A computational study has been conducted to analyse the performance of a centrifugal compressor with different types of diffusers under various levels of impeller—diffuser interactions. Vaneless (VLD), vaned (VD), low solidity vaned (LSVD), and partial vaned diffusers (PVD) are used for this purpose. The study is carried out using commercial software ANSYS CFX. The interaction level is varied by varying the radial gap between the impeller and diffuser by keeping the diffuser vane at three different radial locations. Numerical simulations have been conducted for four different flow coefficients. At design flow coefficient maximum efficiency occurs when the leading edge is at R3 (ratio of radius of the diffuser leading edge to the impeller tip radius) = 1.10 for all vane-type diffuser configurations. At below design flow coefficient higher stage efficiency occurs when the diffuser vanes are kept far away (R3 = 1.15) and at above design flow coefficient R3 = 1.05 gives better efficiency. The highest ...

Computational investigation of impeller—diffuser interaction in a centrifugal compressor with different types of diffusers

The present investigation is undertaken to study the performance of an existing stage of an industrial centrifugal compressor with a vaneless diffuser and is aimed at improving the efficiency of the compressor stage through the use of a low-solidity (LSD) vaned diffuser. The experiments were conducted at a tip Mach number of 0.35. The LSD vane is formed from a standard aerofoil profile with marginal modification in the trailing edge region. The study was conducted at a solidity ratio of 0.81, which is considered as the optimum for the chosen stage. The overall stage performance for different diffuser vane setting angles was evaluated in terms of flow coefficient, head coefficient, polytropic efficiency and static pressure recovery coefficient. The performance parameters are normalized with respect to those of the vaneless diffuser at design flow. Improvement in performance as well as static pressure recovery was observed with LSD vanes as compared with a vaneless diffuser configuration. Variation ...

Effect of the setting angle of a low-solidity vaned diffuser on the performance of a centrifugal compressor stage:

A Numerical Study of the Unsteady Interaction Effects on Diffuser Performance in a Centrifugal Compressor

In an effort to improve the performance of centrifugal compressors, detailed studies were carried out on three different impeller-diffuser configurations covering a wide range of design flo...

Prasad Mukkavilli

Papers

Effect of the setting angle of a low-solidity vaned diffuser on the performance of a centrifugal compressor stage:

Flow Studies on a Centrifugal Compressor Stage With Low Solidity Diffuser Vanes