Studies on the Three-Dimensional Flow Field in a Turbine Scroll: (1st Report, Measurements of Secondary Flows)

A test apparatus of turbine scroll has been devised to investigate the secondary flow phenomena in a scroll. The scroll is of parallel end wall type and based on a logarithmic spiral. The three-dimensional flow field survey can be taken in arbitrary cross sections with a probe traverse mechanism newly developed. Distributions of total pressure and three velocity components have been measured in detail, using a five-hole probe. The secondary flow field is to be dominated by passage vortices on end walls and low energy fluid accumulating on a tongue. The favorable pressure gradient and the inward secondary flow on end walls suppress an extreme growth of wall boundary layer. However, the secondary flow affects the distribution of exit flow angle in the direction of passage height.