|Acquisition Program: ||F-18 E/F Aircrafts, 414 Engine|| Objective: ||Develop a sequential energetic secondary fuel injection scheme in order to reduce combustion instabilities and to enhance performance of chemical propulsion systems.
|| Description: ||Combustion instabilities not only result in deterioration of combustor performance that affects the overall propulsion system performance, but also may lead to extensive fatigue and vibration that can reduce the operational life, and may even lead to premature failure. Among the various technologies tried over the past decades, secondary fuel injection has shown promise and ease of retrofit. Research has shown that the timing of secondary fuel injection (with respect to the vortex formation in the combustor flow) has a tremendous impact on the stability enhancement. However, the secondary fuel injection involves additional components and weight, which may affect the overall system performance. It is proposed that a pulsed fuel delivery system is used, and highly energetic secondary fuel is utilized. This will enable a reduction in secondary fuel otherwise required, lead to complete combustion, and increase thermal output. An increased thrust will thus be possible without an increase in the combustor volume, and the specific primary fuel consumption can also be reduced. The secondary fuel can be high energy strained hydrocarbon fuels, such as cubane and benzvalene derivatives or nano metallic particle of aluminum (Alex), boron etc.
|| ||PHASE I: Identify a suitable high energy secondary fuel, and develop injection scheme for sequential injection. Conduct flow and/or computational studies to understand particle size, distribution and trajectories.
|| ||PHASE II: Design and fabricate a secondary fuel injection and a simple test combustor or modify an off the shelf combustor (simple liquid fuel engine), and perform pulsed secondary fuel injection studies. Investigate vibration levels, noise and thermal output with and without secondary fuel injection. Validate computational tools for use in Phase III.
|| ||PHASE III: Install the secondary fuel system in a realistic engine (Government-provided), and perform a full parametric evaluation of thrust performance, vibration and noise, and fuel utilization. Optimize system integration for retrofit, and provide new design criteria.
PRIVATE SECTOR COMMERCIAL POTENTIAL/|| ||DUAL-USE APPLICATIONS: This technology will have an impact on all types of chemical propulsion devices used. Further, this will be applicable to stationary power generators and auxiliary power units, pulse combustors and pulse detonation engines.
|| References: ||1. B. Pang et.al, “Combustion and Mixing Control Studies for Advanced Propulsion”, Combustion Processes in Propulsion: Control, Noise and Pulse Detonation, Elsevier, pp.169-180, 2006.
2. K.H. Yu et. al, "Liquid Fuel Active Control for RAMJET Combustors", Advances in Chemical Propulsion - Science to Technology, CRC Press , pp 341-360., 2002.|
|Keywords: ||Combustion Instability, Performance Improvement, Fuel consumption, Vibrations, Missile and Aircraft Propulsion|