Numerical modeling of chemistry and gas dynamics during shock-induced ethylene combustion

Clifford, L.

doi:10.1016/0140-6701(96)88902-8

Cited by 1 publication

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A mathematical expression representing the response variable as a function of the parameter space then takes the place of the full model in the numerical ow solver, reducing greatly the computation time. This technique has been used, for example, by Oran et al 35 and Oran and Boris 36 for induction times, and Clifford et al 37 for both induction time and energy release.…”

Section: Mechanism Reduction Proceduresmentioning

confidence: 97%

Reduced Kinetics Mechanisms for Ram Accelerator Combustion

Petersen

Hanson

1999

Journal of Propulsion and Power

121

View full text Add to dashboard Cite

Two skeletal kinetics mechanisms for reactive CH 4 /O 2 and H 2 /O 2 ram accelerator ow elds are presented. Both models were derived from a 190-reaction, 38-species kinetics mechanism (RAMEC or RAM accelerator MEChanism) that successfully reproduces the high-pressure (>50 atm), low-dilution (<70%), fuel-rich chemistry of ram accelerator mixtures. The reduction procedure for the CH 4 /O 2 mechanism utilized a detailed-reduction technique with ignition delay time and heat release as the selection criteria. The methane-based mechanism (REDRAM or REDuced RAM accelerator mechanism) contains 34 reactions and 22 species and predicts ignition times to better than 5% and postcombustion temperatures to within 10 K of the full mechanism for a representative range of ram accelerator mixtures and conditions. This CH 4 /O 2 mechanism is an improvement over existing reduced methane-oxidation mechanisms that are based on lower-pressure, higher-temperature chemistry. An 18-step, 9-species mechanism is presented for hydrogen-based ram accelerator combustion that is based on the H 2 /O 2 submechanism of the RAMEC/Gas Research Institute GRI-Mech 1.2 methane-oxidation mechanism. The H 2 /O 2 kinetics model includes HO 2 and H 2 O 2 chemistry near the second and third explosion limits, necessary for ignition at ram accelerator pressures but lacking in certain nite rate chemistry models currently in use. IntroductionT HROUGHOUT the development of the ram accelerator concept, modeling of the complex ow eld has receivedparticular attention. The high-pressure, reacting ow eld of the ram accelerator presents an ongoing challenge to numerical modelers, particularly in the interaction between chemistry and hydrodynamics. The ram accelerator, described in detail by Hertzberg et al. 1 and Bruckner et al., 2 utilizes a projectile injected at supersonic speeds into a tube lled with a combustible mixture. Shock waves between the projectile body and the tube walls compress and heat the mixture; the ensuing combustion creates a pressure increase at the rear of the projectile, producing thrust that propels the projectile to very high speeds. The existence and location of the shock and/or detonation pattern depends on the velocity of the projectile relative to the Chapman-Jouguet speed of the mixture. Accurate numerical models of the reacting ow are needed in the design phase to ensure optimal heat release and thrust, avoiding, e.g., ignition in the forebody boundary layer.Nonetheless, computational limitations force many numerical modelersto assume either equilibriumor one-stepchemistry.For example, one-dimensional,control-volume-basedgasdynamicmodels have been used with some success in predicting subdetonative ram accelerator performance, 1¡3 but they are limited to equilibrium chemistry. 4 Early computational uid dynamics (CFD) analyses assumed one-step, global reactions for both H 2 /O 2 -based 5 and CH 4 /O 2 -based 6 calculations. Oversimpli ed chemistry has certain drawbacks, however, including instantaneous conversion of reactants to products...

show abstract

Section: Mechanism Reduction Proceduresmentioning

confidence: 97%