Untersuchimg der instationaren Stromung cines beschaufelten by Stahlecker D.

By Stahlecker D.

This Ph.D. thesis bargains with the experimental research of the unsteady 3 dimensional stream in a centrifugal compressor vaned diffuser via the LDV (Laser-Doppler-Velocimeter) dimension approach. via the research of intensive measurements conducted within the excessive subsonic stream regime of the experimental compressor a contribution to a greater perception view and realizing of the advanced move within the vaned diffuser is entire. also, the played and 3 dimensional LDV measurements whole and expand the present experimental information base of centrifugal compressor flow.In order to accomplish LDV measurements less than the tricky stipulations in a slender channel width diffuser (16.8 mm), it's been necessary to adapt a commercially on hand LDV approach. those diversifications implied advancements of the signal-to-noise ratio of the uncooked LDV bursts, also a brand new subtle and obvious facts acquisition and processing method was once demonstrated. In a different improvement part, the LDV size method, used to be prolonged so as to 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 aspect and at half load with diverse circumferential Mach numbers. The impeller go out circulation and the stream alongside the diffuser midline has been measured. zone measurements were performed in different planes parallel and basic to the impeller axis. The time averaged and time resolved stream has been analysed. accordingly LDV info has been section averaged and in terms of time averaged research the information used to be averaged afterwards arithmetically. the common Jet/Wake constitution of centrifugal compressor impeller circulate is proven for this impeller. The time resolved viscous wake blending is gifted. The wake blending is finished more often than not at the back of the diffuser throat. quarter measurements within the diffuser throat express already the presence of a secondary movement vortex.At. volatile working issues measurements were played with Rotating Stall and Mild-Surge. The uncooked info has been processed with a Multiple-Conditional Sampling info processing process, in the course of Rotating Stall various move areas might be distinctive. A cell-flow zone with moderate badeflow from the diffuser into the impeller and a sound-flow sector within the last impeller go out go part. With the point-wise measuring LDV process it. was once attainable to trap the channel vortex within the rear a part of the diffuser channel in the course of Rotating Stall.In Mild-Surge the harmonic quantity circulate fluctuations are proven within the speed profiles, which leads to backfiow on the low circumferential Mach quantity 0.4.Part of this paintings are QuickTime animations of the diffuser stream, which offer a accomplished perception into the unsteady 3 dimensional circulate in a diversified centrifugal compressor. The animations awl on CD-ROM or can be downloaded from the net (www.lsm.ethz.eh).