Material Solution for Electron Transpiration Cooling of Leading Edges: E.T.-cooling
Abstract
Our Nation must reinvigorate its research in hypersonic flight, both for missiles and aircrafts. Critical to hypersonic flight are materials that can with stand ultra-high heat fluxes, extreme temperatures, high stagnation pressures, large vibration loads and oxidative dissociation reactions, for a number of key components in the hypersonic vehicle. One of the most serious challenges for hypersonic vehicles still lies in developing the right combination of materials that can survive the severe and demanding conditions imposed at the leading edges (LEs). In order to achieve the desired speeds, the LEs are required to have a very sharp geometry in order to increase the lift-to-drag ratio (see insert of Fig.1 for LE coupon shape). The heat flux (q) is inversely dependent on the radius of curvature (rn) at LEs: q~ ?p_?/r_n V_?^3, where p? and V? are the freestream mass density and velocity. Presently, there are no materials that offer a solution to hypersonic LEs for reusable platforms. Radiative cooling is limited at sharp LEs. There are just a few materials having a thermal conductivity sufficient for heat transfer cooling, but the thermomechanical stresses and the damage generated by oxidation can limit that thermal performance. Ablative cooling could result in shape changes that compromises the speed of the vehicle and the overall mechanical integrity of the LE. State-of-the-art active fluidic transpiration cooling has been reported to be able to reduce heat fluxes by up to 1000W/cm2, but this number alone is insufficient for the requirements of >>1500W/cm2. In order to get off the present pathway of performance, a new and innovative approach to reducing heat flux is required. Any approach to resolve the problematic stated by the transition from the current technology to the red line is inherently high risk / high gain. This program focuses on a unique combination of high temperature dielectric and structural materials together with intentional architectural and topology design that will enable the possibility of electron transpiration cooling for leading edges, assisted by passive and active solutions to ensure thermo-mechanical stability of the hybrid LE.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 06, 2020
- Source ID
- W911NF2010012
Entities
People
- D. Viehland
Organizations
- Army Contracting Command
- Defense Advanced Research Projects Agency
- Virginia Tech