SBIR-STTR Award

Spark ignition of a bi-propellant rocket engine is a classic, proven, and generally reliable process. However, timing can be critical, and the control logic, additional electronic components and wiring adds complexity, cost and weight. These factors can be especially undesirable for small attitude or reaction control engines. The proposed innovation uses a novel method to excite a piezo-ceramic crystal using the initiation of propellant flow to the engine. When the propellant valves are opened, the precise timing of the spark relative to propellant flow, as well as the flow start transient, are governed by the geometry of the device. Hence, precise, repeatable start conditions should be achieved with no additional control logic or complexity. Furthermore, the piezo-ceramic crystal is integral to (and embedded in) the igniter body, thereby completely eliminating external wiring and associated complexity. A bench-top demonstration of one manifestation of the device (incorporating only one very simple moving part) has already demonstrated basic feasibility. Other manifestations with no moving parts what-so-ever (at the macroscopic scale) may also be viable, and will be investigated. Phase 1 TLR advancement goal is from 3 to 5, with Phase 2 goal of 7.

Under a Phase 1 effort, IES successfully developed and demonstrated a spark ignition concept where propellant flow drives a very simple fluid mechanical oscillator to excite a piezoelectric crystal. The Phase 1 effort exceeded expectations, with the device demonstrating reliable ignition of both hydrogen and propane fuels, and achieving in excess of 1 million impact cycles (40,000 start cycles) during fatigue testing without measureable degradation. Several spin-off concepts were also identified that provide additional options for improving spark ignition system design. For Phase 2, IES proposes an accelerated, 18 month effort to refine design concepts and analysis tools, and then develop specific ignition system designs for two customer applications, with the intention of having these ignition systems demonstrated in engine ground testing during Phase 2 and ready to start flight qualification immediately following the Phase 2 effort. Both customers (United Launch Alliance and Pratt Whitney Rocketdyne) have expressed interest and commitment in participating in the Phase 2 activity, making engines and facilities available for development testing, and integrating any resulting viable products into their flight engines. The ULA application is a new gaseous bipropellant H2/O2 attitude control thruster, for which the piezoelectric igniter is ideal as a simple, direct ignition source. The PWR application is for an evolved RL-10 study currently underway, for which the piezoelectric system might be scaled up or used as a pilot igniter for a torch, or make use of another spin-off concept that was identified during the Phase 1 effort. The timing of this Phase 2 effort coincides perfectly with near term needs of both these customers, as well as for other small engine applications in work to replace catalytic hydrazine engines with bi-propellant engines that will require a simple and reliable ignition source.