SBIR-STTR Award

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 turbines 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 scramjetScramjet,hypersonic,Plasma-Assisted Combustion,ignition,air-breathing,Propulsion

Reusable hypersonic aircraft platforms offer the possibility to provide valuable ISR and global strike capabilities to the DoD to bolster national security. Future aircraft powered by Turbine Based Combined Cycle (TBCC) architectures will have the ability to take off from a runway using a traditional turbine propulsion mode and accelerate to hypersonic speed, transitioning from turbine to ramjet and potentially scramjet propulsion modes along the way. There are significant technical challenges for this propulsion architecture since a single propulsion system must operate over a large range of Mach number and dynamic pressure. Most TBCC investigations have focused on “over-under” configurations as studied in DARPA’s Falcon program or side-by-side configurations, requiring two separate engines and engine flowpaths – a turbine and a dual mode ramjet (DMRJ), for example – but these arrangements are not the only possible solutions. Whether the propulsion architecture is an over/under turbine+DMRJ solution or a turboramjet solution, there are several major challenges facing the design of combined-cycle hypersonic systems. These challenges have been explored in several DARPA and USAF programs. A key fundamental challenge impacting both turboramjet and TBCC architectures is maintaining robust operability over the range of the flight envelope especially at low speeds and high altitudes where pressures in the engine are low. The proposed work will evaluate the possible system level benefits of using selective energy deposition to enhance operability and potentially enable significant system level benefits. These benefits will be studied through engine ground testing and analyzed through trade studies for relevant combined cycle vehicle concepts.