Effects of Chemical Reaction Models on Simulations of Scramjet Nozzle Flow

2014 ◽  
Vol 490-491 ◽  
pp. 931-935
Author(s):  
Xiao Yuan Zhang ◽  
Li Zi Qin ◽  
Yu Liu
Keyword(s):  
Kinetic Models ◽  
Chemical Kinetic ◽  
Numerical Results ◽  
Supersonic Combustion ◽  
Equilibrium Flow ◽  
Reaction Models ◽  
Total Temperature ◽  
Supersonic Combustion Ramjet ◽  
Quantity Of Heat ◽  
Non Equilibrium

The chemical non-equilibrium flow of supersonic combustion ramjet (scramjet) nozzle is numerical simulated with different chemical kinetic models to research the effects on numerical results of the nozzle performance. The numerical results show that total temperature is increased due to the recombination of dissociation compositions and the combustion of the residual fuel. The effect of the combustion of the residual fuel is more obvious in this paper, and the effect to the performance of the nozzle is noticeable. The species of the compositions in the models influence the quantity of heat sending out when it get equilibrium, so the 9-species chemical kinetic models are more suitable in the simulation of the scramjet nozzle chemical non-equilibrium flows.

Analysis and Calculation of Chemical Non-Equilibrium Turbulent Flow in a Scramjet Nozzle

2009 ◽  
Author(s):  
X. Y. Wang ◽  
G. N. Xie ◽  
B. Sunde´n
Keyword(s):  
Chemical Reactions ◽  
Chemical Reaction ◽  
Equilibrium Flow ◽  
Reaction Models ◽  
Mass Fractions ◽  
Total Temperature ◽  
Inlet Conditions ◽  
And Performance ◽  
Equilibrium Chemical ◽  
Non Equilibrium

In this paper, 7-species, 8-step finite-rate chemical reaction models of the non-equilibrium flow in a scramjet single expansion ramp nozzle have been investigated numerically. Chemical reactions and mass transfer under various freestream Mach numbers and flight height conditions are performed by the RNG k-ε turbulence model. The fluid flow in the nozzle is analyzed under non-equilibrium chemical reactions and frozen flow conditions. It is shown that the total temperature is obviously increased while the total pressure is evidently decreased in the chemical non-equilibrium flow at certain inlet conditions. The mass fractions of H2 and O2 are decreased while that of H2O is increased, and the mass fraction of N2 is almost identical throughout the whole reaction process. This indicates that combustion occurs in the nozzle, and the scramjet nozzle can supplement the combustion in a supersonic combustor so that the performance of the nozzle can be increased. It can be found that there are eddies in the chemical non-equilibrium flow because of the variations of the mass fractions of O2, H, O and OH. These eddies suggest that the variations of the mass fractions of O2, H, O and OH is non-monotonic. Although the flow is speeded up, the chemical reaction at the beginning part of the nozzle is faster than that downstream. The calculation shows that the non-equilibrium chemical reactions should always be considered in investigations of the flow and performance of scramjet nozzles.

Analysis of numerical results in high temperature congealment and chemistry non-equilibrium flow field

2002 ◽  
Vol 1 (1) ◽  
pp. 26-34
Author(s):  
Hong-tao Zheng ◽  
Zhi-yong Tan ◽  
Hai-ou Sun ◽  
Chun-liang Zhou ◽  
Zhi-ming Li
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
Numerical Results ◽  
Equilibrium Flow ◽  
Non Equilibrium

Numerical Simulation of Chemical Non-Equilibrium Flow in Hydrocarbon Fuel Scramjet Nozzle

2013 ◽  
Vol 717 ◽  
pp. 342-346
Author(s):  
Bin Zhang ◽  
Bin Yu ◽  
Hong Liu ◽  
Fang Chen
Keyword(s):  
Numerical Simulation ◽  
Dynamic Characteristics ◽  
Great Influence ◽  
Hydrocarbon Fuel ◽  
Equilibrium Flow ◽  
Finite Rate ◽  
Reaction Models ◽  
Nozzle Inlet ◽  
Equilibrium Effect ◽  
Non Equilibrium

Based on 8-specice, 12-step finite-rate chemical reaction models, the chemical non-equilibrium flows of hydrocarbon fuel scramjet single expansion ramp nozzle (SERN) were numerical simulated. The chemical dynamic characteristics of flow in SERN were analyzed in detail. The performances of SERN were compared at various inlet static temperatures. The numerical results show that the chemical non-equilibrium effect had great influence on the performance of the nozzle at the relatively high inlet static temperature. However, influence induced by chemical non-equilibrium effect can be neglected when nozzle inlet static temperature is less than 2500K.

Restrictions on chemical kinetic models

1976 ◽  
Vol 65 (1) ◽  
pp. 284-292 ◽  
Author(s):  
David Wallwork ◽  
Alan S. Perelson
Keyword(s):  
Kinetic Models ◽  
Chemical Kinetic

scholarly journals Arabidopsis plants perform arithmetic division to prevent starvation at night

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Antonio Scialdone ◽  
Sam T Mugford ◽  
Doreen Feike ◽  
Alastair Skeffington ◽  
Philippa Borrill ◽  
...  
Keyword(s):  
Biological System ◽  
Kinetic Models ◽  
Starch Content ◽  
Chemical Kinetic ◽  
Light Period ◽  
Starch Degradation ◽  
Degradation Pathways ◽  
Night Time ◽  
Expected Time ◽  
Time Period

Photosynthetic starch reserves that accumulate in Arabidopsis leaves during the day decrease approximately linearly with time at night to support metabolism and growth. We find that the rate of decrease is adjusted to accommodate variation in the time of onset of darkness and starch content, such that reserves last almost precisely until dawn. Generation of these dynamics therefore requires an arithmetic division computation between the starch content and expected time to dawn. We introduce two novel chemical kinetic models capable of implementing analog arithmetic division. Predictions from the models are successfully tested in plants perturbed by a night-time light period or by mutations in starch degradation pathways. Our experiments indicate which components of the starch degradation apparatus may be important for appropriate arithmetic division. Our results are potentially relevant for any biological system dependent on a food reserve for survival over a predictable time period.

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