Untersuchimg der instationaren Stromung cines beschaufelten - download pdf or read online

By Stahlecker D.

This Ph.D. thesis offers with the experimental research of the unsteady 3 dimensional movement in a centrifugal compressor vaned diffuser by way of the LDV (Laser-Doppler-Velocimeter) dimension approach. via the research of in depth measurements performed within the excessive subsonic stream regime of the experimental compressor a contribution to a greater perception view and figuring out of the advanced stream within the vaned diffuser is complete. also, the played and 3 dimensional LDV measurements entire and expand the present experimental info base of centrifugal compressor flow.In order to accomplish LDV measurements below the tough stipulations in a slender channel width diffuser (16.8 mm), it's been necessary to adapt a commercially to be had LDV method. those diversifications implied advancements of the signal-to-noise ratio of the uncooked LDV bursts, also a brand new subtle and obvious info acquisition and processing method was once tested. In an additional improvement section, the LDV size process, was once prolonged so one can practice measurements and research in volatile working issues with Rotating Stall and Mild-Surge.Measurements m $tahle working issues were played on the most sensible element and at half load with diversified circumferential Mach numbers. The impeller go out move and the circulation alongside the diffuser midline has been measured. quarter measurements were performed in numerous planes parallel and basic to the impeller axis. The time averaged and time resolved move has been analysed. therefore LDV info has been part averaged and in terms of time averaged research the knowledge used to be averaged afterwards arithmetically. the common Jet/Wake constitution of centrifugal compressor impeller circulation is proven for this impeller. The time resolved viscous wake blending is gifted. The wake blending is done in most cases at the back of the diffuser throat. region measurements within the diffuser throat convey already the presence of a secondary circulation vortex.At. volatile working issues measurements were played with Rotating Stall and Mild-Surge. The uncooked information has been processed with a Multiple-Conditional Sampling facts processing strategy, in the course of Rotating Stall assorted circulation areas will be exceptional. A cell-flow zone with mild badeflow from the diffuser into the impeller and a sound-flow area within the closing impeller go out pass part. With the point-wise measuring LDV method it. was once attainable to catch the channel vortex within the rear a part of the diffuser channel in the course of Rotating Stall.In Mild-Surge the harmonic quantity circulation fluctuations are proven within the pace profiles, which leads to backfiow on the low circumferential Mach quantity 0.4.Part of this paintings are QuickTime animations of the diffuser movement, which offer a entire perception into the unsteady 3 dimensional circulate in a diversified centrifugal compressor. The animations awl on CD-ROM or might be downloaded from the internet (www.lsm.ethz.eh).