An Experimental Study of the Intermittent Properties of the Boundary Layer Pressure Field During Transition on a Flat Plate,

摘要

The properties of the intermittent wall pressure field were measured in the transition boundary layer on a large flat plate in an anechoic wind tunnel. Natural transition was achieved with a mild favorable pressure gradient at Reynolds numbers,based on downstream distance from the plate's leading edge,in excess of 7,000,000. The development of the laminar boundary layer prior to transition was in agreement with numerical solutions to the laminar boundary layer equations and with stability criteria for pressure gradient effects. The temporal,spatial,and spectral properties of the transition wall pressure field associated with the natural transition process occurring on the plate are obtained as a function of the intermittency factor,and compared with those of the fully turbulent pressure field. Specifically,the mean-square pressure,spectral densities,convection velocities,distributions of burst periods and burst rates of the intermittent pressure field are computed from the data. (Author)