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45th AIAA/ASME/SAE/ASEE joint propulsion conference & exhibit

45th AIAA/ASME/SAE/ASEE joint propulsion conference & exhibit
45th AIAA/ASME/SAE/ASEE joint propulsion conference & exhibit
Large-eddy simulations (LES) have been performed for kerosene spray combustion with methane pilot flame in a model dual mode ramjet chamber with a cavity flame holder under the condition of incoming Mach number of 2 and inlet static temperature of 520K. Three cases are compared with a constant equivalence ratio of methane pilot flame of 0.08 but different equivalence ratios of kerosene of 0.10, 0.25 and 0.6 respectively.

It is found that the kerosene spray interacts strongly with the pilot flame in the near wall region and the depth of the spray penetration plays an important part in deciding the characteristics of the combustion process, its efficiency and the overall heat addition. When kerosene injection mass is small, spray droplets are close to the wall and are surrounded with the hot air generated by the pilot flame, the kerosene spray combustion can achieve higher efficiency due to nearly complete combustion in the separated boundary layer.

However the resulting flame flashback in the boundary layer could induce engine inlet unstarting. When spray droplets penetrate further into the freestream but still interact intermittently with the pilot flame, the spray evaporation is enhanced by the pilot flame front. The heat consumption during this process results in rich fuel mixtures accumulating near the wall. Thus the combustion processes of both kerosene vapor and pilot gas have been suppressed, resulting the lowest heat releasing. As for the case of droplets fully penetrating into the freestream core, small amount of evaporated kerosene gradually diffuses and burns further downstream of the pilot flame, accompanied with the lowest combustion efficiency due to low evaporation rate but the relative higher additional heat releasing.

Considering inlet unstarting is undesirable for ramjet engine under a relative low flight Mach number, unless the boundary layer separation can be controlled, the deep spray penetration is to be used to achieve a better overall kerosene combustion performance. However the spray combustion efficiency still needs to be improved.
Zhang, Man
4452127c-1d09-4075-ac11-8e71844dd713
Hu, Zhiwei
dd985844-1e6b-44ba-9e1d-fa57c6c88d65
Luo, Kaihong
68e8a1d7-7994-450f-9949-b03ccdd8ce70
He, Guoqiang
dad6774f-aa35-498b-9a43-d31d638545c0
Zhang, Man
4452127c-1d09-4075-ac11-8e71844dd713
Hu, Zhiwei
dd985844-1e6b-44ba-9e1d-fa57c6c88d65
Luo, Kaihong
68e8a1d7-7994-450f-9949-b03ccdd8ce70
He, Guoqiang
dad6774f-aa35-498b-9a43-d31d638545c0

Zhang, Man, Hu, Zhiwei, Luo, Kaihong and He, Guoqiang (2009) 45th AIAA/ASME/SAE/ASEE joint propulsion conference & exhibit. 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, , Denver, United States. 02 - 05 Aug 2009. 15 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

Large-eddy simulations (LES) have been performed for kerosene spray combustion with methane pilot flame in a model dual mode ramjet chamber with a cavity flame holder under the condition of incoming Mach number of 2 and inlet static temperature of 520K. Three cases are compared with a constant equivalence ratio of methane pilot flame of 0.08 but different equivalence ratios of kerosene of 0.10, 0.25 and 0.6 respectively.

It is found that the kerosene spray interacts strongly with the pilot flame in the near wall region and the depth of the spray penetration plays an important part in deciding the characteristics of the combustion process, its efficiency and the overall heat addition. When kerosene injection mass is small, spray droplets are close to the wall and are surrounded with the hot air generated by the pilot flame, the kerosene spray combustion can achieve higher efficiency due to nearly complete combustion in the separated boundary layer.

However the resulting flame flashback in the boundary layer could induce engine inlet unstarting. When spray droplets penetrate further into the freestream but still interact intermittently with the pilot flame, the spray evaporation is enhanced by the pilot flame front. The heat consumption during this process results in rich fuel mixtures accumulating near the wall. Thus the combustion processes of both kerosene vapor and pilot gas have been suppressed, resulting the lowest heat releasing. As for the case of droplets fully penetrating into the freestream core, small amount of evaporated kerosene gradually diffuses and burns further downstream of the pilot flame, accompanied with the lowest combustion efficiency due to low evaporation rate but the relative higher additional heat releasing.

Considering inlet unstarting is undesirable for ramjet engine under a relative low flight Mach number, unless the boundary layer separation can be controlled, the deep spray penetration is to be used to achieve a better overall kerosene combustion performance. However the spray combustion efficiency still needs to be improved.

Text
AIAA-2009-5385-192.pdf - Accepted Manuscript
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More information

Published date: August 2009
Venue - Dates: 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, , Denver, United States, 2009-08-02 - 2009-08-05
Organisations: Aerodynamics & Flight Mechanics

Identifiers

Local EPrints ID: 155583
URI: http://eprints.soton.ac.uk/id/eprint/155583
PURE UUID: 5ff7f80a-3ed7-4392-9b30-aa01f1c6e03b

Catalogue record

Date deposited: 28 May 2010 10:15
Last modified: 14 Mar 2024 01:39

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Contributors

Author: Man Zhang
Author: Zhiwei Hu
Author: Kaihong Luo
Author: Guoqiang He

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