Numerical Investigation of Jet Angle Effect on Airfoil Stall Control

Junkyu Kim,Taesoon Kim,Solkeun Jee,Junseong Lee,Minwoo Kim,Young Min Park,Jiseop Lim

doi:10.3390/app9152960

Abstract

Numerical study on flow separation control is conducted for a stalled airfoil with steady-blowing jet. Stall conditions relevant to a rotorcraft are of interest here. Both static and dynamic stalls are simulated with solving compressible Reynolds-averaged Navier-Stokes equations. It is expected that a jet flow, if it is applied properly, provides additional momentum in the boundary layer which is susceptible to flow separation at high angles of attack. The jet angle can influence on the augmentation of the flow momentum in the boundary layer which helps to delay or suppress the stall. Two distinct jet angles are selected to investigate the impact of the jet angle on the control authority. A tangential jet with a shallow jet angle to the surface is able to provide the additional momentum to the flow, whereas a chord-normal jet with a large jet angle simply averts the external flow. The tangential jet reduces the shape factor of the boundary layer, lowering the susceptibility to the flow separation and delaying both the static and dynamic stalls.

Highlights

Stall occurs when a lifting surface loses its aerodynamic lift
The stall phenomenon associated with a lifting body at fixed angles of attack is called static stall
The compressible Reynolds-averaged Navier-Stokes (RANS) equations are computed numerically using the unstructured flow solver SU2, which was developed in Stanford university [39]

Summary

Introduction

Stall occurs when a lifting surface loses its aerodynamic lift. A well-known reason of the stall is the flow separation from the surface. An airfoil would be the best example to describe the stall phenomenon. As the angle of attack α increases beyond the stall angle αstall , the flow is detached from the airfoil surface. The flow may separate from the trailing edge or the leading edge, depending on the specific design of an airfoil and the flow condition including the Reynolds and Mach numbers [1]. The stall phenomenon associated with a lifting body at fixed angles of attack is called static stall

Methods

Results

Conclusion