A Study on Detonation of Jet-A Using a Reduced Mechanism

Ajmani, Kumud; Kundu, K.P.; Penko, Paul F.

doi:10.2514/6.2010-1515

Cited by 14 publications

(13 citation statements)

References 8 publications

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“…In the combustion mechanism for Jet-A used in the present study, the activation energy for the fuel breakup reaction (reaction 1, in the appendix) depends on the temperature of the reactants 11 . Furthermore, this reaction mechanism was developed for high-pressure conditions (p0 ≥ 10 bar).…”

Section: T/t0mentioning

confidence: 99%

Computational Study of Pulsejet-Driven Pressure Gain Combustors at High-Pressure

Yungster

Paxson

Perkins

2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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This study explores computationally the performance characteristics of a pulsejet-driven pressure-gain combustor concept at high pressure conditions. The combustor consists of a pulsejet and an ejector, both housed within a shroud. The pulsejet-ejector-shroud (PES) combination forms an annular combustor across which a total pressure rise can be achieved. The computations carried out to date have demonstrated an overall pressure rise of 1.2% while achieving an overall temperature ratio commensurate with modern gas turbines. A combustor design capable of achieving even a small pressure gain rather than the usual 4%-8% loss found in conventional combustors is highly desirable since it would produce a significant improvement in engine specific fuel consumption. Computed NOx emissions for this type of combustor are also presented, and are shown to be comparable to those of conventional gas turbine engines at corresponding compressor pressure ratios. An analysis of the differences in the operation of a pulsejet at atmospheric and high-pressure conditions is also presented. The computations utilize a reduced combustion mechanism for Jet-A fuel and include a novel model for the pulsejet's reed valve. The results presented here are only preliminary, since neither the ejector nor the pulsejet itself have been optimized. With the numerical platform developed here, future optimization studies can be pursued. Nomenclaturef = pulsejet operating frequency Lpj = pulsejet length mp = primary (pulsejet) massflow rate mT = Total massflow rate (pulsejet + bypass) p = pressure p0 = inlet total pressure pback = back pressure pinj = fuel injection pressure T = temperature T0 = inlet total temperature t = t i m e tefi = end of fuel injection time tsfi = start of fuel injection time tsvc = start of valve closing time tsvo = start of valve opening time tvfc = valve fully closed time tvfo = valve fully open time x = axial coordinate Φ = equivalence ratio

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Section: T/t0mentioning

confidence: 99%

Computational Study of Pulsejet-Driven Pressure Gain Combustors at High-Pressure

Yungster

Paxson

Perkins

2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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“…A reduced combustion mechanism, based on the model developed by Ajmani et al 10,11 , consisting of 10 elementary reactions among 11 reacting species was utilized. An additional four NO reactions, taken from Jachimowski's hydrogen-air combustion model 12 were added to this model.…”

Section: Computational Modelmentioning

confidence: 99%

Effect of Fuel Injection and Mixing Characteristics on Pulse-Combustor Performance at High-Pressure

Yungster¹,

Paxson²,

Perkins³

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Recent calculations of pulse-combustors operating at high-pressure conditions produced pressure gains significantly lower than those observed experimentally and computationally at atmospheric conditions. The factors limiting the pressure-gain at high-pressure conditions are identified, and the effects of fuel injection and air mixing characteristics on performance are investigated. New pulse-combustor configurations were developed, and the results show that by suitable changes to the combustor geometry, fuel injection scheme and valve dynamics the performance of the pulse-combustor operating at high-pressure conditions can be increased to levels comparable to those observed at atmospheric conditions. In addition, the new configurations can significantly reduce the levels of NOx emissions. One particular configuration resulted in extremely low levels of NO, producing an emission index much less than one, although at a lower pressure-gain. Calculations at representative cruise conditions demonstrated that pulse-combustors can achieve a high level of performance at such conditions. Nomenclature EI= emission index (grams of NO per kilogram of fuel) f = pulse combustor operating frequency Lpc = pulse combustor length mT = total massflow rate p = pressure p0 = inlet total pressure pavg = average combustor pressure pinj = fuel injection pressure pmax = peak combustor pressure T = temperature T0 = inlet total temperature t = t i m e tefi = end of fuel injection time tsfi = start of fuel injection time tsvc = start of valve closing time tsvo = start of valve opening time tvfc = valve fully closed time tvfo = valve fully open time x = axial coordinate Φ = equivalence ratio

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“…The NOx production downstream of the pilots is higher than the intermediates (see figure 8), even though the local FAR for the pilots is almost half of that of the intermediates. This is perhaps because the simplex nozzles (used in the pilots) tend to generate more NOx than airblast nozzles (used in the intermediates) -a phenomenon also noted in the computational and experimental work reported by Ajmani [8].…”

Section: Computational Results (Ncc Rans)mentioning

confidence: 90%

“…A finite-rate chemistry model is used to compute the species source-terms for Jet-A/Air chemistry. The chemistry model incorporates 13 species and 18 chemical reaction steps [8] and is detailed in Table 1.…”

Section: Computational Modelmentioning

confidence: 99%

Simulations of NOx Emissions from Low Emissions Discrete Jet Injector Combustor Tests

Ajmani¹,

Breisacher²

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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An experimental and computational study was conducted to evaluate the performance and emissions characteristics of a candidate Lean Direct Injection (LDI) combustor configuration with a mix of simplex and airblast injectors. The National Combustion Code (NCC) was used to predict the experimentally measured EINOx emissions for test conditions representing low power, medium power, and high-power engine cycle conditions. Of the six cases modeled with the NCC using a reduced-kinetics finite-rate mechanism and lagrangian spray modeling, reasonable predictions of combustor exit temperature and EINOx were obtained at two highpower cycle conditions.

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A Study on Detonation of Jet-A Using a Reduced Mechanism

Cited by 14 publications

References 8 publications

Computational Study of Pulsejet-Driven Pressure Gain Combustors at High-Pressure

Computational Study of Pulsejet-Driven Pressure Gain Combustors at High-Pressure

Effect of Fuel Injection and Mixing Characteristics on Pulse-Combustor Performance at High-Pressure

Simulations of NOx Emissions from Low Emissions Discrete Jet Injector Combustor Tests

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