scholarly journals Large-Eddy Simulations for the Wall Heat Flux Prediction of a Film-Cooled Single-Element Combustion Chamber

2020 ◽  
pp. 223-234
Author(s):  
R. Olmeda ◽  
P. Breda ◽  
C. Stemmer ◽  
M. Pfitzner
Keyword(s):  
Heat Flux ◽  
Combustion Chamber ◽  
Film Cooling ◽  
Structural Integrity ◽  
Cooling System ◽  
Rocket Engine ◽  
Large Eddy Simulations ◽  
Wall Heat Flux ◽  
Single Element ◽  
Large Eddy

Abstract In order for modern launcher engines to work at their optimum, film cooling can be used to preserve the structural integrity of the combustion chamber. The analysis of this cooling system by means of CFD is complex due to the extreme physical conditions and effects like turbulent fluctuations damping and recombination processes in the boundary layer which locally change the transport properties of the fluid. The combustion phenomena are modeled by means of Flamelet tables taking into account the enthalpy loss in the proximity of the chamber walls. In this work, Large-Eddy Simulations of a single-element combustion chamber experimentally investigated at the Technical University of Munich are carried out at cooled and non-cooled conditions. Compared with the experiment, the LES shows improved results with respect to RANS simulations published. The influence of wall roughness on the wall heat flux is also studied, as it plays an important role for the lifespan of a rocket engine combustors.

Large Eddy Simulations of Film-Cooling Flows With a Micro-Ramp Vortex Generator

2011 ◽  
Author(s):  
Aaron F. Shinn ◽  
S. Pratap Vanka
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Vortex Generator ◽  
Vortex Pair ◽  
Large Eddy Simulations ◽  
Wind Tunnel Experiments ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flows ◽  
Large Eddy

Large Eddy Simulations were performed to study the effect of a micro-ramp on an inclined turbulent jet interacting with a cross-flow in a film-cooling configuration. The micro-ramp vortex generator is placed downstream of the film-cooling jet. Changes in vortex structure and film-cooling effectiveness are evaluated and the genesis of the counter-rotating vortex pair in the jet is discussed. Results are reported with the jet modeled using a plenum/pipe configuration. This configuration was designed based on previous wind tunnel experiments at NASA Glenn Research Center, and the present results are meant to supplement those experiments. It is found that the micro-ramp improves film-cooling effectiveness by generating near-wall counter-rotating vortices which help entrain coolant from the jet and transport it to the surface. The pair of vortices generated by the micro-ramp are of opposite sense to the vortex pair embedded in the jet.

scholarly journals Influence of Polyisobutylene Kerosene Additive on Combustion Efficiency in a Liquid Propellant Rocket Engine

Aerospace ◽  
2019 ◽  
Vol 6 (12) ◽  
pp. 129 ◽  
Author(s):  
Igor Borovik ◽  
Evgeniy Strokach ◽  
Alexander Kozlov ◽  
Valeriy Gaponov ◽  
Vladimir Chvanov ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Film Cooling ◽  
Rocket Engine ◽  
Combustion Efficiency ◽  
Liquid Propellant ◽  
Gaseous Oxygen ◽  
Wall Film ◽  
Measurement Results ◽  
Liquid Propellant Rocket Engine ◽  
Propellant Rocket

The combustion of kerosene with the polymer additive polyisobutylene (PIB) was experimentally investigated. The aim of the study was to measure the effect of PIB kerosene on the efficiency of combustion chamber cooling and the combustion efficiency of the liquid propellant for a rocket engine operating on kerosene and gaseous oxygen (GOX). The study was conducted on an experimental rocket engine using kerosene wall film cooling in the combustion chamber. Fire tests showed that the addition of polyisobutylene to kerosene had no significant effect on the combustion efficiency. However, analysis of the wall temperature measurement results showed that the use of PIB kerosene is more effective for film cooling than pure kerosene, which can increase the efficiency of combustion chamber cooling and subsequently increase its reliability and reusability. Thus, the findings of this study are expected to be of use in further investigations of wall film cooling efficiency.

scholarly journals Numerical Simulation of Reactive Flows in Overexpanded Supersonic Nozzle with Film Cooling

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Mohamed Sellam ◽  
Amer Chpoun
Keyword(s):  
Film Cooling ◽  
Structural Integrity ◽  
Safety Issue ◽  
Rocket Engine ◽  
Supersonic Nozzle ◽  
Nozzle Geometry ◽  
Nozzle Flow ◽  
Rocket Engines ◽  
Flow Conditions ◽  
Reactive Flows

Reignition phenomena occurring in a supersonic nozzle flow may present a crucial safety issue for rocket propulsion systems. These phenomena concern mainly rocket engines which use H2gas (GH2) in the film cooling device, particularly when the nozzle operates under over expanded flow conditions at sea level or at low altitudes. Consequently, the induced wall thermal loads can lead to the nozzle geometry alteration, which in turn, leads to the appearance of strong side loads that may be detrimental to the rocket engine structural integrity. It is therefore necessary to understand both aerodynamic and chemical mechanisms that are at the origin of these processes. This paper is a numerical contribution which reports results from CFD analysis carried out for supersonic reactive flows in a planar nozzle cooled with GH2film. Like the experimental observations, CFD simulations showed their ability to highlight these phenomena for the same nozzle flow conditions. Induced thermal load are also analyzed in terms of cooling efficiency and the results already give an idea on their magnitude. It was also shown that slightly increasing the film injection pressure can avoid the reignition phenomena by moving the separation shock towards the nozzle exit section.

Large-Eddy Simulations of a Cylindrical Film Cooling Hole

2013 ◽  
Vol 27 (2) ◽  
pp. 255-273 ◽  
Author(s):  
Perry L. Johnson ◽  
Jayanta S. Kapat
Keyword(s):  
Film Cooling ◽  
Large Eddy Simulations ◽  
Large Eddy ◽  
Cooling Hole

Effect of Blowing Ratio in the Near-Stagnation Region of a Three-Row Leading Edge Film Cooling Geometry Using Large Eddy Simulations

2009 ◽  
Author(s):  
Sai Shrinivas Sreedharan ◽  
Danesh K. Tafti
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Large Eddy Simulations ◽  
Stagnation Region ◽  
Stagnation Line ◽  
Blowing Ratio ◽  
Large Eddy ◽  
Adiabatic Effectiveness ◽  
Compound Angle

Computational studies are carried out using Large Eddy Simulations (LES) to investigate the effect of coolant to mainstream blowing ratio in a leading edge region of a film cooled vane. The three row leading edge vane geometry is modeled as a symmetric semi-cylinder with a flat afterbody. One row of coolant holes is located along the stagnation line and the other two rows of coolant holes are located at ±21.3° from the stagnation line. The coolant is injected at 45° to the vane surface with 90° compound angle injection. The coolant to mainstream density ratio is set to unity and the freestream Reynolds number based on leading edge diameter is 32000. Blowing ratios (B.R.) of 0.5, 1.0, 1.5, and 2.0 are investigated. It is found that the stagnation cooling jets penetrate much further into the mainstream, both in the normal and lateral directions, than the off-stagnation jets for all blowing ratios. Jet dilution is characterized by turbulent diffusion and entrainment. The strength of both mechanisms increases with blowing ratio. The adiabatic effectiveness in the stagnation region initially increases with blowing ratio but then generally decreases as the blowing ratio increases further. Immediately downstream of off-stagnation injection, the adiabatic effectiveness is highest at B.R. = 0.5. However, further downstream the larger mass of coolant injected at higher blowing ratios, in spite of the larger jet penetration and dilution, increases the effectiveness with blowing ratio.

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