Wall Shear Measurement Technology for Plume Surface Interactions

Exploration of the Moon, or Mars, will require the development of landing vehicles, whose primary task is to decelerate its cargo and safely touch down on the surface. However, this is not a trivial task for these types of environments. As the jet/plume from the rocket engine, used to decelerate the vehicle, encounters the surface, the low atmospheric pressure, low gravity, and cohesive soil properties result in large dust clouds and even crater formation. These phenomena are called plume surface interactions (PSI). Incremental progress is being made to study PSI through a series of proposed test campaigns being conducted at multiple NASA Research Centers and utilizing large vacuum chamber facilities, such as the MSFC TS300 or LARC 60#39; Sphere, and tested under relevant conditions. One critical instrumentation need that NASA has identified is direct surface (wall) shear stress measurements. In the Lunar environment, surface shear stress is the primary driving force by which surface erosion occurs. To overcome this technology gap, Ahmic and our assembled team propose to adapt our state-of-the-art wall shear measurement technology to target surface erosion environments occurring in plume surface interactions.In Phase II, Ahmic will develop two wall shear sensor capabilities. The first will target wall shear measurements at the extremely high temperatures produced in rocket plumes ndash; exceeding 2000 K. The second will target wall shear measurements at the extremely low magnitudes produced in simulated Lunar and Martian environments where the ambient pressure is a low vacuum. The sensors will then be validated in clean-flow wind tunnel facilities before being tested in jet/plume impingement environments, including hot-flow and vacuum facilities. In addition, the sensors will also be used to expand a test methodology of reducing active surface erosion testing to a series of discrete static-surface contour geometries to be instrumented and tested in a PSI environment.