The Effects of Design and Operating Variables on the Response of an Axial Flow Fan to Inlet Flow Distortions.

摘要

This thesis presents the results of a study of total-pressure and velocity circumferential distortions in an axial-flow fan. Distorted inlet flow is an important problem to the turbomachine designer because nonuniform and distorted flows cause noise, vibration, a reduction in efficiency, and also a reduction in the stability limits for a multistage compressor. Some of the sources of a nonuniform flow which are often unavoidable are wakes from upstream struts, sharp bends in the inlet ducting, flow separation in the inlet, and vortices created by ingesting fluid from a boundary layer. The present study was conducted to provide some of the fundamental experimental data needed to understand distorted flow phenomena as affected by design and operating variables. The flow through an isolated rotor was examined at various operating conditions with six different distortions and three different blade stagger angles. Circumferential surveys were conducted upstream and downstream of the rotor using five-hole probes in the non-nulling mode. The measurements with the five-hole probes yielded the axial, circumferential, and radial components of velocity, and the total and static pressure.