Design and Performance Evaluation of a Very Low Flow Coefficient Centrifugal Compressor

Yongsheng Wang,Chaoqun Nie,Feng Lin,Abraham Engeda

doi:10.1155/2013/293486

Abstract

Very low flow coefficient centrifugal compressors are often applied as the last stages of multistage compressors. Due to the lower volume flow rate, the flow channels in the impeller and diffuser are so narrow that friction loss becomes the main factor, which leads to lower efficiency than that of other stages in the same compressors. In addition, most of design methods are generally based on medium flow coefficient centrifugal compressors. Taking on researches on the low flow coefficient centrifugal compressors is significant and necessary. One-dimensional (1D) code, consisting of design and analysis parts, is developed in this study to provide basic geometric data and predict the entire performance of centrifugal compressor. Three-dimensional geometry of the impeller is built. CFD simulation is carried out as well to be compared with 1D prediction. With the continuous geometry adjustment, the final performance of the centrifugal compressor will be fixed once the performance discrepancy between CFD and one-dimensional code is acceptable. The details on the flow field within impeller will be presented through CFD.

Highlights

Centrifugal compressors are usually designed in the flow coefficient range φ = 0.01 to 0.16
Based on the above research results, this study aims to design an efficient low flow coefficient centrifugal compressor with wide operating range
Further validations through more impellers have to be done in the future to confirm if a constant coefficient for total pressure ratio exists between CFD and 1D code

Summary

Introduction

Centrifugal compressors are usually designed in the flow coefficient range φ = 0.01 to 0.16. Often the need arises to design very low or high flow coefficient, φ, radial stages, but the aerodynamic challenges are not easy to satisfy; a designer usually has to make certain critical decisions. Narrow radial impellers (smaller φ and smaller eye diameter) have nontwisted blades. Wider impellers (larger φ and larger eye diameter) by contrast have twisted blades for better adaption to local flow conditions.

Objectives

Methods

Findings

Conclusion