NASA 1998 SBIR Phase I

PROPOSAL NUMBER: 98-1 03.03-4800A

PROJECT TITLE: Low Frequency, High Amplitude Fuel Modulator to Enhance Lean Blowout and Reduce Emissions in AST Combustors


This SBIR project proposes to develop a fuel pulsing Lean Direct Injection (LDI) nozzle that reduces nozzle blowout equivalence ratio (phi) and reduces NOx emissions by 90% compared to ICAO 1996 standards. In contrast to high frequency (> 10,000 Hz), low motion piezoelectric actuators studied in the past, the proposed LDI will utilize an innovative low frequency (< 1000 Hz) magnetic actuator with up to full off/on modulation. It is expected that the nozzle blowout phi will be reduced by 33% compared to previously demonstrated lean blowout. This will allow the nozzle phi at full power conditions to be reduced by 33%, resulting in a potential 35-fold reduction in NOx. An existing simplex-piloted airblast LDI fuel nozzle will be employed, and the pilot fuel flow will be pulsed off/on at a frequency (to be determined) between 200-1000 Hz in order to anchor the flame within a 5 msec recirculation zone. Since half of the time the fuel will be twice the average fuelflow, the nozzle blowout phi can be theoretically halved. A magnetic fuel actuator proposed by our selected small business subcontractor, Fluid Jet Associates, will be used to pulse the pilot fuel and parametrically vary the frequency and amplitude. Prototype LDI hardware will be fabricated using CFDRCs past experience and CFD analysis. Experimental tests will then be run at atmospheric pressure and idle inlet air temperatures to show the overall feasibility of improving lean blowout and maintaining low CO levels at idle. In Phase II, single nozzle flametube rig testing will be performed at NASA LeRC to determine CO and NOx emissions at various operating conditions, and to assess fuel pulsation strategies for active control of thermoacoustic oscillations at lean, takeoff conditions. To fully demonstrate the design, engine-quality fuel modulators and LDI nozzles will be fabricated and tested in a full annular combustor at an engine company (e.g. GEAE).


The fuel modulator and fuel pulsing LDI nozzle developed in this SBIR have the potential of significantly reducing NOx emissions in gas turbine engines, both aero and industrial versions. Gas turbine engine manufacturers (e.g. General Electric and AlliedSignal) have expressed interest in the concept. The rights to fabricate the nozzle will be sold to a fuel nozzle vendor in exchange for a royalty fee for every production nozzle.


Dan Nickolaus
CFD Research Corporation
215 Wynn Drive
Huntsville , AL 35805


CFD Research Corporation
215 Wynn Dr.
Huntsville , AL 35805