Time-accurate, turbulence resolved DES for transonic and supersonic aerodynamic loads.
Transient external aerodynamic loads are critical for launch vehicle and payload development. These loads have traditionally been obtained with a combination of wind tunnel testing and Large Eddy Simulation (LES) Computational Fluid Dynamics (CFD) models, both of which are expensive solutions. Quartus, together with our partners at Siemens and Maya HTT, have developed time-accurate, turbulence resolved Detached Eddy Simulations (DES) for transonic and supersonic aerodynamic loads in STAR-CCM+. Quartus has demonstrated the accuracy of such methods for predicting aerodynamic loads for transonic termination shocks using test data from the Ares I-X launch vehicle demonstrator.
The heavily instrumented Ares I-X launch vehicle was designed to provide engineers with high fidelity flight data that could be compared against extensive pre-flight wind tunnel testing. This combination provided some of the best data available with which to validate simulation techniques. Accurately predicting aerodynamic loads is critical for a wide variety of commercial applications including launch vehicles, military and commercial aircraft, rocket engines, gas turbine engines and supersonic vehicles. Aerodynamic loads drive:
- Equipment random vibration qual. test levels
- Interior (payload) acoustic qual test levels
- Panel flutter, sonic fatigue, and snap-through failure
The goal of this project was to examine the use of DES for transonic and supersonic aerodynamic load prediction and compare the accuracy of simulation results to the best available test data. Key CFD post processing quantities for this analysis were frequency filtered pressure animations, Root Mean Squared (RMS) surface fluctuating pressure, spectral Sound Pressure Level (SPL), and spatial correlation.
Ares I-X geometry is used to develop a CFD model for transonic termination shock around an expansion corner and check calculations against flight and test data. Fluctuating surface pressures are shown to match well with experimental data up to the first expansion corner and SPL spectra match well upstream of the first expansion corner for lower frequencies. Spatial correlation agrees with commonly accepted convection velocity parameters.
The primary comparison metric was RMS surface pressure, but other extracted data included pressure spectra at discrete locations, spatial correlation, and frequency filtered pressures. Both corner peak and expansion corner plateaus are captured by CFD simulations and locations match well with test data.
- Fluid Mechanics