This paper describes a modeling method and a new optimal control approach to investigate a Mach number control problem for the NASA Ames 11-Foot Transonic Wind Tunnel. The flow in the wind tunnel is modeled by the 1-D unsteady Euler equations whose boundary conditions prescribe a controlling action by a compressor. The boundary control inputs to the compressor are in turn controlled by a drive ...

A vanishing viscosity method is formulated for two-dimensional transonic steady irrotational compressible fluid flows with adiabatic constant γ ∈ [1, 3). This formulation allows a family of invariant regions in the phase plane for the corresponding viscous problem, which implies an upper bound uniformly away from cavitation for the viscous approximate velocity fields. Mathematical entropy pairs...

Usually, the first stage of a compressor of a gas turbine works in the region of transonic flow, so that the designer has to take into account a lot of flow details like shocks, boundary layer separation and their interaction, when a new machine is defined. Beside other problems the choice of the blade geometry and profile family is one important consideration. For the design of the blades anal...

To understand / evaluate behaviour of these complex jets freestream interactions, experiments were carried out in the freestream Mach number range of 0.6 to 1.8 varying jet pressure ratios in the range of 1 to about 15 on a twin jet afterbody configuration. Test results show that afterbody total drag in general increased (for the Mach number range of this investigation) with the increase in jet...

A computationally efficient and robust methodology for transonic airfoil design is presented. The approach replaces the direct optimization of an accurate, but computationally expensive, high-fidelity airfoil model by an iterative re-optimization of a corrected low-fidelity model. The low-fidelity model is based on the same governing fluid flow equations as the high-fidelity one, but uses coars...

The optical environment around both a hemisphere-on-cylinder turret and a hemisphereonly turret with flat and conformal windows was characterized at both subsonic and transonic speeds. Data was taken from Mach 0.4 to 0.65 at altitudes from 15,000 ft to 30,000 ft to analyze scaling laws, with a focus on Mach numbers of 0.5 and 0.65. A 25 kHz ShackHartmann wavefront sensor was used to measure the...

This paper presents a strategy using a high fidelity delayed-detached-eddy simulation (DDES) to simulate 3-D fluid-structural interaction for predicting AGARD Wing 445.6 flutter boundary in a transonic flow. A dual-time step implicit unfactored Gauss-Seidel iteration with Roe scheme are employed for the flow solver. The special numerical techniques used herein include: a 5th order WENO scheme f...