Trevor J. Birch

High speed static experimental investigations to estimate control device effectiveness and S&C capabilities

The high speed experimental investigations of a generic UCAV configuration with control surfaces are presented. The current paper covers the design of the model, layout of the control surfaces and the static wind tunnel tests. The tests were performed in both the DNW and BAE Systems High Speed Tunnel facilities and included conditions up to a Mach number of M = 0.9. The experimental results are used to establish a common high speed CFD test matrix for the NATO Task Group STO/AVT-201 for computer code validation and to assess the capability to predict the complex vortical flow and aerodynamic S&C characteristics of moderately leading edge swept configurations.

Computational fluid dynamics methods for hypersonic flow around blunted-cone-cylinder-flare

This paper presents an investigation of numerical schemes for the hypersonic flow around a blunted-cone– cylinder–flare (HB-2). The investigation is based on a finite volume computational fluid dynamics code using the Harten–Lax–van Leer–contact Riemann solver in conjunction with four numerical reconstruction schemes with order of accuracy ranging from second–ninth order. Comparisons are presented with experimental data for the pressure and heat transfer. The results show that very-high-order schemes such as weighted essentially nonoscillatory fifthand ninth-order methods may provide slightly better results for freestreamMach numbers less than 10; however, there are no obvious benefits over second-order methods for Mach numbers greater than 10.

Prediction of Control Effectiveness for a Highly Swept Unmanned Air Vehicle Configuration

A study into the prediction of the effectiveness of different trailing-edge controls on an unmanned combat aerial vehicle configuration, on which complex vortical flow develops at moderate to high angles of attack, is described. Stability and control of these vehicles is demanding and requires early knowledge of the changes in forces and moments from control-surface deflections. Computational results are compared with data from wind-tunnel tests over the Mach number range 0.146≤M≤0.9 for undeflected controls. The effectiveness of the controls at subsonic and transonic conditions is then discussed. The influence of the mesh treatment and turbulence model on the realism of the predictions is considered. The computational-fluid-dynamics predictions show good agreement with measurements and show limited sensitivity to geometry treatment and turbulence model for the flow conditions where the controls are effective. Computational fluid dynamics is shown to be capable of predicting the control-surface influence,...

CFD Predictions of Control Effectiveness for a Generic Highly Swept UCAV Configuration

A computational study has been completed into the transonic aerodynamics of a generic highly swept UCAV configuration with particular attention to the prediction of the effectiveness of a range of trailing edge controls using an automated mesh generation tool and Reynolds averaged Navier-Stokes solver. Computational results are compared with data from wind tunnel tests over the Mach number range 0.5≤M≤0.9 for the case with no control deflections. Results for several different trailing edge controls are then presented and compared with experimental data for a Mach number of 0.7. The computational results provide additional insight into the underlying flow physics.

Evaluation of Dynamic Pressure-Sensitive Paint for Improved Analysis of Cavity Flows and CFD Validation

This study has investigated the use of Dynamic Pressure-Sensitive Paint (DPSP) to analyse the complex multi-dimensional flow-field within a generic small-scale rectangular planform cavity. The analysis and understanding of cavity flows have received renewed interest due to the low-observability requirements for modern military aircraft and Unmanned Combat Aerial Vehicles (UCAVs). This study has demonstrated the use of DPSP to provide unsteady pressure data, from the full model surface coverage of a model-scale cavity ceiling in a transonic Mach number range of 0.70 ≤ M ≤ 0.95. These results were compared against traditional point transducer measurements and also compared with numerical simulations of the cavity flow-field. These comparisons demonstrate that DPSP represents a very useful tool for the validation of numerical data as well as for flow-diagnostic investigations, where point measurements from transducers would provide spatially limited data. Further analysis of the transducer and DPSP data has also demonstrated temporal intermittency of the widely known Rossiter modes within the cavity acoustic signature. This instability has been previously linked to mode switching and a breakdown in the modal generation feedback process within the cavity flowfield.