Large Volume Plasmas for Improved Scramjet Cold Start

A key challenge in scramjet-powered vehicles is ensuring reliable cold start and efficient combustion on hydrocarbon fuels such as JP-10. Ignition delay times for these logistics-friendly hydrocarbons, exceeding 10 ms at 1 bar and T=700 K, are an order of magnitude higher than the combustor residence times. These challenges are especially acute for combined cycle powered hypersonic vehicles where a thrust deficit exists between the high end of the high-Mach turbine’s flight envelope. As such, a steady-state combustion control technology which can maintain combustion at low overall equivalence ratios and operate until dual-mode operation is established may be necessary to improve the low-speed operability of the DMRJ. For boost-to-cruise type systems, developing an IM complaint, light weight ignition and flame holding aid also remains a challenge. For both types of vehicles, plasmas provide a potential solution to the ignition and combustion stability problems however the challenge is developing a system which can generate a plasma in the right location at a sufficiently low energy cost to deposit enough energy and chemical species into the flow to promote ignition and flame stabilization. The proposed Phase I will investigate novel methods of using plasmas to enhance ignition and flame propagation in scramjet