Enhancing Supersonic Rudder Control Surface Using Co-flow Jet Active Flow Control

Abstract

This paper investigates the effects using high lift zero-net mass-flux Co-Flow Jet (CFJ) active flow control on aircraft control surfaces with rudders. The goal is to increase the control ability of rudder control surface of supersonic civil transport (SST) and save energy expenditure. A simplified Concorde vertical tail model is constructed and used as a baseline control surface for parametric trade study using a Reynolds-averaged Navier-Stokes (RANS) solver with Spalart-Allmaras (SA) model. A 3rd order WENO scheme for the inviscid flux is used to resolve the Navier-Stokes equations. The 3D numerical studies indicate that, the Rudder-Stabilizer-CFJ, which was optimal CFJ configuration in two-dimensional simulation, generates jet flows that interfere with each other and thus no longer performs well in three-dimensional situation. The Rudder-CFJ is the optimal location, under which the optimal rudder deflection angle is 45deg, and the optimal jet momentum coefficient is 0.08, which is the largest possible value. Under this condition, the maximum lift enhancement of 63.1% and the maximum lift-drag ratio increment of 18.1% is achieved. When the rudder deflection angle is 45deg, lower jet momentum coefficient will always generate positive lift enhancement and improves both lift-drag ratio and corrected aerodynamic efficiency; at the lowest simulated jet momentum coefficient =0.02, the improvements are 32.8% and 11.62% respectively. When the rudder deflection angle is larger than 45deg, both lift coefficient and its increment drops. For this specific control surface geometry, CFJ does not reduce drag coefficient at all jet momentum coefficient and all rudder deflection angles, but when the udder deflection angle is larger than 30deg, it still can improve both lift-drag ratio and corrected aerodynamic efficiency. CFJ supersonic aircraft rudder shows great potential to substantially reduce the size and weight of control surfaces with high control authority.