Performance of a Turbocharger Compressor With a Range of Low Solidity Vaned Diffusers

The performance of a centrifugal compressor with a range of low solidity diffuser vanes is discussed. The effect of vane leading and trailing edge angle was investigated while maintaining a basic design with 10 vanes and a solidity of 0.69. The diffuser vanes were designed with a circular arc camberline and a specified leading edge angle. The trailing edge angle was varied by specifying a range of angles through which the vanes turned. Vanes with leading edge angles of 65°, 70°, 75°, and 80° were considered together with vane turning angles of 10°, 15° and 20°. All results are compared with those obtained with the standard vaneless diffuser configuration. Despite the low solidity configuration none of the vane designs provided a broad operating range and it would be necessary to deploy a variable geometry arrangement. Vane designs with a leading edge angle of 65° showed a premature surge, and whilst vane designs with a leading edge angle of 80° suppressed surge poor performance occurred at high flow rates. It is shown that the modification of the vane trailing edge angle led to poor matching of the diffuser discharge flow conditions with those required by the collecting volute.