Performance Improvement of the Pressure Ratio and Rotational Speed Calculation of a Centrifugal Compressor Model

In this study, various investigations were performed on the reduction of calculation errors of compressor models which can calculate compressor performance (pressure ratio, rotational speed) at an arbitrary operating point. For this purpose, three compressor models, including the Jensen & Kristensen model and the newly modified model, are presented in this study. By applying these models, the compressor pressure ratio and rotational speed prediction calculation results are compared with four other compressors. From these, we confirmed the performance characteristics of each model and reduced calculation errors near the surge limit, near the choking limit, and in the high speed range, which was a problem in the standard J & K compressor model. Also, the application performance of the compressor model during actual engine operation is presented through an experiment with a 1.4 liter WGT diesel engine. The pressure measurement error had a large effect on the calculation error of the low rotational speed region, and the influence decreased as the rotational speed increased. The calculation error of the compressor rotational speed was less than 10 % when the rotational speed was higher than 33 % of the maximum rotational speed of the compressor, and accuracy was improved as the rotational speed increased.