Experimental and numerical investigations of flow through an annular diffuser with and without struts

Abstract

An exhaust diffuser is a critical component of gas turbine applied to newlineboth the propulsion and power system applications. The exhaust diffuser of an newlineindustrial gas turbine recovers the static pressure by decelerating the turbine newlinedischarge flow. This allows the turbine to be operated at an exhaust pressure newlinelower than the atmospheric one, thus increasing the turbine work. This makes newlinethe diffuser a critical element in the turbomachine environment in terms of newlineefficiency and stability. newlineIn the present work, experimental and numerical investigations newlinehave been carried out to study the effect of the struts on the flow structure and newlinethe performance of the diffusers. The strut design that has the potential to newlinechange the diffuser dynamics was tested. Two types of struts were used newlinenamely baseline struts and tapered struts. newlineThe objective of the present work is to provide an improved newlineunderstanding of flow passing over struts in an annular diffuser. The flow newlinethrough the diffuser with and without struts was studied. Experiments were newlineconducted for three different types of configurations namely diffuser without newlinestruts, with baseline struts and with tapered struts. A low speed sub sonic newlinewind tunnel was used to conduct the experiments. A Five-hole pitot pressure newlineprobe with a digital manometer was used to measure pressure, and a newlineDANTEC Dynamics make constant temperature anemometer with X-probe was used to measure mean velocity, and turbulence level in axial and radial newlinedirections. Measurements were taken at a number of radial positions across newlinethe annulus, and at some circumferential positions at each axial location along newlinethe diffuser. The results suggest that tapered design perform better than the newlinebaseline design.