Numerical Investigation of Jet Angle Effect on Airfoil Stall Control

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.

Numerical Study on Combustion-Driven Jet Actuation for Aerodynamic Control of Airfoil Flows

“…Conversely, at low angles of attack, the flow control impact of the impulsive actuation becomes minor; therefore, minimal variations in the aerodynamic forces and moment are observed. The related experimental [19][20][21][22] and computational [23][24][25] studies reported that jet actuation could have a minor impact on the flow control where the external flow is well attached to the surface. This is probably related to the minimum variations in the forces and moment observed in the current computations at low angles of attack, where the flow is already well attached to the suction surface.…”

“…Various actuation methods have been explored to control the aerodynamic characteristic of a lifting body [3][4][5][6][7][8][9][10][11][12]. Müller-Vahl and Greenblatt [3], Kim et al [4], and Gardner et al [5][6][7] focused on the impact of a steady-blowing jet on lifting surfaces, revealing changes in aerodynamic characteristics with the use of a high-momentum steady-blowing jet. Feng et al [8] assessed the effects of constant suction actuation at different locations on a plunging SD7003 airfoil, using RANS computations for analysis.…”

“…Matalanis et al [19][20][21] and Tan et al [22] utilized COMPACT actuation to control the dynamic stall phenomena under various flow conditions. Jee et al [23] and Kim et al [24][25][26] applied this flow control technique to mitigate rotorcraft-related dynamic stall events using unsteady Reynolds-averaged Navier-Stokes simulation (URANS) computations. Later, Kim et al [27] conducted a delayed detached-eddy simulation (DDES) to investigate detailed flow physics with the jet actuation, and they identified two distinct time scales associated with the flow features closely related to variations in the aerodynamic performance of a lifting body.…”

“…On the other hand, the unsteady Reynolds-averaged Navier-Stokes (URANS) approach has been effectively utilized for aerodynamic simulations under compressible flow conditions [34][35][36][37][38][39][40][41]. Furthermore, ongoing research in the area of flow control [8,10,24,[24][25][26]42] indicates the continued relevance of the URANS approach for investigating flow mechanisms, complementing experimental studies.…”

Investigation of Shock Wave Oscillation Suppression by Overflow in the Supersonic Inlet

“…Additionally, the active suppression measure is usually required. Flow control is often carried out for boundary layer flow, including the passive flow control method [21] and the active flow control method, such as the jet control [22], the suction control [23] and so on. As an extensively used active flow control technology, the boundary layer suction has a broad prospect in suppressing the boundary layer separation [24,25] and could improve the backpressure inhibition ability of the inlet [26].…”