Innovative Aerodynamic Measurement for Integrated Hypersonic Inlets

Hypersonic propulsion systems are characterized by high Mach number gas flows over vehicle surfaces and internal ducts. The flow often includes shock waves, shear layers, vortices, and separated flows. The ability to measure surface quantities such as pressure and skin friction on a hypersonic inlet model would provide increased insight into the complex flow characteristics that govern inlet performance. Unfortunately, nonintrusive sensors require optical access that has been difficult to obtain. Optical sensors for measurements of pressure (Fast Pressure Sensitive Paint), skin friction (Surface Stress Sensitive Films), and velocity (Particle Image Velocimetry) offer non-intrusive measurements on surfaces and in flows, exactly the capability that is needed to study hypersonic inlets. Unfortunately, the size of the cameras and light sources that are used in these systems have precluded their use in regions like an internal duct. During the past several years, camera and LED technology has evolved dramatically resulting in small packages for both imaging and illumination. Combining this new hardware with state-of-the-art optical technology for fast PSP, S3F, and PIV measurements will result in a set of sensors that can be miniaturized and utilized for non-intrusive measurements of pressure, skin friction, and velocity in traditionally inaccessible regions of the model. BENEFIT: There is considerable interest in measurements of unsteady pressure, velocity, and skin friction for evaluation of computational models and study of flow physics on hypersonic inlets, compressors, artificial hearts, and other wind tunnel models and flows with limited optical access. This system will provide advancement of the state-of-the-art in this field as the proposed research will develop a system for the measurement of continuous distributions of skin friction and pressure, and velocity in the flow, using a miniaturized imaging system for data acquisition. This miniaturized imaging package, and the associated tools should be useful for a variety of fluid studies from hypersonic inlets and low speed wind tunnels to biological flows.