Numerical study of performance curve incline and instability flow phenomena in low flow rates according to absolute flow angle change at axial-flow pump inlet

Abstract

This study predicted the performance of an inlet guide vane to be installed later by applying an absolute flow angle (ß) at the axial pump inlet. The pump’s performance was predicted based on changes in inlet ß, and the influence of variations in inlet ß on the low-flow area was analyzed. For turbulence flow analyses, the Reynolds-averaged Navier–Stokes equations were discretized based on the finite volume method. The internal flow was analyzed in detail through transient analysis. Furthermore, the impact of changes in the absolute flow angle at the inlet on the rotating stall occurring inside the pump in the low-flow-rate region was analyzed. The analysis of the internal flow field confirmed that the absolute flow angle at the inlet affects the stability of the internal flow. Results showed that energy reduction and efficient operation scenarios can be established compared with the existing valve control method by changing inlet ß. Through fast Fourier-transform analysis, it was confirmed that when the inlet angle (θ) is changed in the low-flow-rate region, a more stable operation is possible compared with the existing one.