Effects of Impeller Blade Loading on Industrial Centrifugal Compressor Performance and Stability

Multistage centrifugal compressors are widely used in the oil and gas industry for various applications. As energy demand increases, the compressor has been challenged to have both high efficiency and broad operating range in order to minimize the life-cycle operation cost. Therefore much effort has been devoted to improve performance of the centrifugal impeller through various design methods. This paper highlights experiences gained in the development of three-dimensional impeller design in an effort combining different design methodologies and experimental investigations. In the present paper, a radial impeller in a medium specific speed range was designed through the conventional direct approach as the baseline. Then, it was redesigned with a different loading profile and a challenged loading magnitude by means of the inverse design method. To assess the two design approaches, the resulting two impellers were manufactured and tested in a closed-loop compressor test rig. The experimental investigation consists of both the performance test and detailed traverse test measuring the flow field downstream of the impeller. The paper presents the comparison of impeller performance and time-averaged data of the downstream flow field between the two impellers. Analysis of the test data illustrates the critical impact of the blade loading on the overall compressor performance and stability.