Recent developments and applications of quantitative laserlight sheet measuring techniques in turbomachinerycomponents

Abstract

Concerning the further development of gas turbineengines, advances of the aero-thermodynamic design can beachieved most efficiently by co-operative efforts aimed at theimprovement of both the numerical simulation methods and theexperimental test and measurement techniques. Rapiddevelopment of numerical capability is accompanied by increasingdemands on experimental data. In this context significantinstrumentation research efforts are being conducted to developthe needed measurement technologies.Because of the need for reduced experimental costs planarmeasurement techniques have undergone a rapid pace ofdevelopment. Three newly developed quantitative light sheettechniques utilizing the scattered light of tracer particles aredescribed in this paper. First a Doppler global velocimetry(DGV) system optimized for time-averaged three componentvelocity measurements is presented. The system, which uses asingle viewing direction in conjunction with three differentillumination directions enables very accurate velocitymeasurements.Second a quantitative light sheet (QLS) technique forquantitative mass fraction measurements in mixing processes istreated. To apply the technique the inflow of the mixingexperiment must consist at least of two separate flows, one ofwhich can be seeded while the other remains unseeded. DGV andQLS results obtained from experimental investigation in a modelcombuster are presented.Third a method named tracer-based shock visualization(TSV) is described which is capable of determining the shapeand structure of shock waves in transonic flows by analysing thesudden increase of flow density across a shock. Results taken in atransonic compressor are presented.