Effect of Variable Axial Chord on a Low-Pressure Turbine Blade

An experimentalstudy was conducted in a two-dimensional linearcascade,withfocuson thesuctionsurfaceof a low-pressureturbine blade. FlowReynolds numbers, based on exit velocity and suction surface length, werevaried from 50,000 to 300,000. The axial chord of the blades was varied by tail extenders from 0 to 15% beyond design. The effects of Reynolds number on a low-pressure turbine cascade blade with tail extensions were investigated. Separation wasobserved at all Reynoldsnumbers and in all e ow cases. This study has shown that for certain cases, changing the axial cord of a low-pressure turbine blade by use of tail extensions provided a clear improvement in boundary-layer behavior, which results in better overall blade performance. The most profound effect of the tail extensionswasseenwhenthetailwasshort.Therewasnoadditionaladvantagewhenthetailextensionswerelonger than 6.1%oftheaxial chord.Theshortesttail extension resulted in the greatest zoneof performanceenhancement. The longer tail extension resulted in a smaller region of performance enhancement.