Numerical Simulation and Unsteady Combustion Model of AP/HTPB Propellant under Depressurization by Rotation

2019 ◽  
Vol 44 (4) ◽  
pp. 493-504 ◽  
Author(s):  
Zhen‐W. Ye ◽  
Yong‐G. Yu
Keyword(s):  
Numerical Simulation ◽  
Combustion Model ◽  
Unsteady Combustion ◽  
Htpb Propellant

Self-Excited Oscillations in Combustors With Spray Atomisers

2000 ◽  
Author(s):  
M. Zhu ◽  
A. P. Dowling ◽  
K. N. C. Bray
Keyword(s):  
Strong Dependence ◽  
Pressure Fluctuations ◽  
Low Frequency ◽  
Coupled System ◽  
Fuel Spray ◽  
Combustion Model ◽  
Unsteady Combustion ◽  
Low Frequency Oscillation ◽  
Monte Carlo Techniques ◽  
Excited Oscillation

Combustors with fuel-spray atomisers are susceptible to a low-frequency oscillation, particularly at idle and sub-idle conditions. For aero-engine combustors, the frequency of this oscillation is typically in the range 50–120Hz and is commonly caused ‘rumble’. In the current work, Computational Fluid Dynamics (CFD) is used to simulate this self-excited oscillation. The combustion model uses Monte Carlo techniques to give simultaneous solutions of the Williams’ spray equation together with the equations of turbulent reactive flow. The unsteady combustion is calculated by the laminar flamelet presumed pdf method. A quasi-steady description of fuel atomiser behaviour is used to couple the inlet flow in the combustor. A choking condition is employed at turbine inlet. The effects of the atomiser and the combustor geometry on the unsteady combustion are studied. The results show that, for some atomisers, with a strong dependence of mean droplet size on air velocity, the coupled system undergoes low frequency oscillations. The numerical results are analysed to provide insight into the rumble phenomena. Basically, pressure variations in the combustor alter the inlet air and fuel spray characteristics, thereby changing the rate of combustion. This in turn leads to local ‘hot spots’, which generate pressure fluctuations as they convect through the downstream nozzle.

Direct Numerical Simulation of Turbulent Spray Combustion

2000 ◽  
Author(s):  
J. Réveillon
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Diffusion Flame ◽  
Turbulent Combustion ◽  
Diffusion Flames ◽  
Combustion Model ◽  
Two Phase ◽  
Complex Interactions ◽  
The Rich ◽  
Global And Local

Abstract Turbulent combustion of two-phase flows is studied by 2D direct numerical simulation. A spray of droplets is injected inside a jet with a preheated coflow. Triple flames appear to represent the global structure of the flame around the spray. Attention is focused upon global and local flame structures and droplet histories. A whole range of combustion phenomena are observed and described. The observed prevailing occurrence, for example, of the rich premixed flame compared to the diffusion flame is of great importance for any turbulent combustion model which must accurately estimate the heat release rate. This prevailing structure depends strongly on the droplet size and combustion. A competition between premixed and diffusion regimes may also occur. It has been shown that in some cases, local clusters of droplets are able either to cross the main flame front and burn in pure oxidizer or to break through the diffusion flame. It is observed that very complex interactions can emerge locally between premixed flames, diffusion flames and droplets.

Investigation of Numerical Simulation in Combustion Chamber Predictability

2011 ◽  
Vol 317-319 ◽  
pp. 2085-2090
Author(s):  
Rang Shu Xu ◽  
Ling Niu ◽  
Xin Zhu Weng ◽  
Long Xu ◽  
Min Li Bai
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Combustion Chamber ◽  
Domain Boundary ◽  
Combustion Model ◽  
Physical Parameters ◽  
Computational Domain ◽  
Flame Tube ◽  
Vof Model ◽  
Adopted Model

For the purpose of increasing applicability of combustion chamber simulation, computational domain, boundary condition, simplicity of complicated structures, mesh generation and physical parameters are investigated in this paper. An annular combustion chamber of some aero-engine is studied by means of predictive numerical simulation. The computational domain includes diffuser, swirler, inner flame tube, inner ring of combustion chamber and the flow channel of all the holes on the wall of flame tube. The film cooling holes row was simplified into a slit filled with porous media. Realizable k-turbulent model and non-premixed combustion model were adopted. Model of pressure atomization nozzle were calibrated and validated through inner nozzle flow property two-phase flow VOF model and experimental data. Physical parameters are express through polynomial functions. A commercial CFD code was adopted on a high performance computing cluster with parallel algorithm and the solving method are high-order discretization scheme. The velocity, pressure, temperature, fuel spray, density of fuel and productions, etc. are calculated and validated with the experimental data.

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