Combustion in Solid Fuel Ramjets
Abstract
A solid fuel ramjet (SFRJ) is a propulsion device that burns solid fuel with ram-compressed air to produce thrust. These devices are the subject of significant interest to the defense community because of their high specific impulse, high density-specific impulse, mechanical simplicity, and potential for throttle control. A typical SFRJ consists of four major components: (1) a supersonic inlet, (2) a solid fuel combustor, (3) an aft-mixing section, and (4) an exit nozzle. The combustor of an SFRJ includes a composite fuel grain (composed of a wide range of solid propellants) and an air injection device, typically a backward-facing step. The reacting flow-field within the combustor is complex, with spatio-temporal dynamics evolving over an extremely wide range of scales and thermo-chemical states. Individual elements of the solid fuel combustor design have strong influence on the flow properties throughoutthe system and the global performance of the propulsion device. The strength of interscale, multiphysics coupling in ramjet propulsion systems dictates that detailed measurements and analysis of this problem must accurately capture the geometry and flow conditions of flight systems. The main goal of this program is to accelerate the development of solid fuel ramjet combustors with a coupled experimental and mathematical characterization of multi-phase, reacting flow processes at flight-relevant scales and flow conditions. The specific technical objectives are to: (1) develop spatially- and temporally-resolved optical diagnostics to characterize thermo-physical properties of the turbulent flow, the progress of chemical reactions, and the regression of the fuel surface; (2) complete a series of parametric tests with varying flow conditions and varying fuel grain composition to experimentally measure the structure and dynamics of the velocity field and the corresponding reaction zone, the gas temperature field, the fuel surface temperature, and the fuel surfaceregression rate across widely varying flow and chemical scales; (3) quantify the effects of radiation heat transfer and flow-path geometry with regression rate measurements in an axisymmetric configuration at flow conditions corresponding to the parametric tests in objective (2); (4) measure the transient response of the fuel regression rate to prescribed, time-varying air flow rates and characterize the controlling mechanisms of dynamic burning in sold fuel ramjets; (5) develop a physics-informed, data-driven model to describe solid fuel ramjet operability and performance response to parametric modeling inputs based on experimentalmeasurements. The proposed experimental work-plan was strategically developed to complement and extend ongoing basic and applied research activities in this technical area at Purdue. The experimental measurements performed in this work have been coordinated withpartners at the NAWCWD, the NRL, multiple industrial partners, and other peer institutions to support other efforts collaborative efforts within the community. The proposed characterization of solid fuel ramjet performance using advanced diagnostics in two highly-effective and precisely controlled experiments along with concomitant data-driven modeling will provide the detailed insight neededto advance the design of flight-ready, high-performance solid fuel ramjet propulsion systems. This page is approved for public release.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 12, 2023
- Source ID
- N000142312301
Entities
People
- Carson D. Slabaugh
Organizations
- Office of Naval Research
- Purdue University
- United States Navy