Characteristics of Transient Deployment of Delta Wing Actuators inside a Boundary Layer: An Experimental and Computational Study

Abstract

Delta wing actuators hinged at the wall beneath a flow have been deployed inside in the flow with an angular velocity between 10 and 100 rad/s. The transient flow field has been simulated experimentally in a low speed wind tunnel and computationally by using CFD with moving boundaries capabilities. The results indicated that all lift and drag force coefficients during the transient deployment are different than the corresponding coefficients under stationary conditions at the same deployment angle. These dynamic effects depend on the Strouhal number which can be considered as the ratio the Stokes to Reynolds number of the flow. It was found that these effects are augmented with increasing Strouhal number and decrease with increasing boundary layer thickness. Reasonable agreement has been found between computational and experimental data. Nomenclature ar = Radial acceleration at = Tangential acceleration CD = Drag force coefficient in the x direction CL = Lift force coefficient in the y direction Re = Reynolds number, Re=U0h/ν dt = time step St = ωh 2 /ν, Stokes number