SBIR-STTR Award

The purpose of this initiative is to develop a revolutionary shear-sensitive film that when applied to a surface under hypersonic flow conditions, would allow for global and instantaneous measurements of wall shear stress. The shear-sensitive film will have a temporal resolution greater than or equal to 1KHz, will be capable of measuring shear stresses up to 250Pa or greater, and will be capabile of doing so in environments with tempearutres up to 395K at Mach 5-7 on canonical geometries in Phase II, whereby the end of Phase II, the technology will be TRL 5. The defense-critical development of the shear stress measurement method on surfaces under hypersonic conditions will serve as proff-of-concept for its further development in Phase II.

Benefit:
The outcome of Phase I will be to deliver a next-generation shear-sensitive film that when applied to a hypersonic surface, would allow for global and instantaneous measurements of wall shear stress. In Phase I, we will demonstrate its capabilities to make these measurements accurately under temperatures up to 395K and Mach 5 and beyond. This will set the stage for us to extend this to temperatures up to 493K and Mach 5-7 for phase II, whereby the technology will be TRL 5 ready; at this point, the technology will have been well developed to make these measurements in environments beyond what has been stipulated for Phase II. This technology will pave the way in accurately predicting boundary layer flow transition and separation under hypersonic conditions. This affects the distribution of skin friction on the hypersonic surface, that when integrated, affects predictions of flight performance parameters, such as lift, drag, and moment coefficients. Furthermore, knowing where separation occurs accurately would allow for effective boundary layer control. In this regard, industry is particularly interested in the technology proposed in this STTR submission in that it has the strong potential to deliver a method whereby skin friction distribution over a surface under hypersonic conditions can be obtained accurately under very high spatial and temporal resolutions, and without being sensitive to pressure or temperature. Furthermore, using appropriate relations, heat transfer can also be inferred from the skin friction measurements. In this regard, the anticipated benefits/potential commerical applications are huge.

Keywords:
hypersonic, hypersonic, wall shear stress

This initiative will develop a novel approach for making instantaneous global measurements of shear stress at aerodynamic surfaces. This is critical because shear stress is one of two fundamental forces theoretical and experimental aerodynamicists aim to calculate and measure for all aerodynamic surfaces, the second being static pressure. In order to obtain two-dimensional information using traditional methods, one must use a large number of these point-measurement sensors that are individually attached/machined onto the tested surface, a process that can be time consuming and expensive. Ultimately, the number of sensors employed limits the spatial resolution of shear stress data that is obtained from such tests. The approach developed in this project will greatly enhance our ability to measure drag locally, globally and instantaneously, predict its development, study flow physics, and develop accurate CFD predictive methods for wall shear stress, and use it towards flow control.

Benefit:
The benefit of our technology is that it will provide a global and non-intrusive method for measuring wall shear stress on hypersonic surfaces, that can be used in large-scale ground test facilities. We envision our technology will serve a wide range of applications in government, military, and aerospace industries in the commercial sectors, as well as in the academic sector, towards advancing the field of hypersonics?????? in both fundamental and applied sciences and engineering.

Keywords: