• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.191-194
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• 2003

A series of computational simulations have been carried out for non-reacting and reacting flows in a supersonic combustor configuration with and without a cavity. Transverse injection of hydrogen, a simplest form of fuel supply, is considered in the present study with the injection pressure of 0.5 and 1.0 ㎫. The corresponding equivalence ratios are 0.17 and 0.33. The work features detailed resolution of the flow and flame dynamics in the combustor, which was not typically available in most of the previous studies. In particular, oscillatory flow characteristics are captured at a scale sufficient to identify the underlying physical mechanisms. Much of the flow unsteadiness is related not only to the cavity, but also to the intrinsic unsteadiness in the flowfield. The interactions between the unsteady flow and flame evolution may cause a large excursion of flow oscillation. The role of the cavity, injection pressure, and amount of heat addition are examined systematically.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.81-86
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• 2007

The air velocity flowing in inner combustion chamber of Scramjet is supersonic and the time of its stay is very short as a few milliseconds. Within this short time, fuel injection, air-fuel mixing, and combustion process should be accomplished. Several methods are suggested for mixing enhancement. Among these, cavity is selected to study for enhancement of mixing. The numerical simulation is performed in the case of freestream Mach number of 2.5 and cavity located in front of fuel jet injection. 8 different sized cavities of length-height ratio were used in order to recognize the effect about cavity size. Also, the case without cavity was analyzed to find the effect of cavity. Used code compared with the result of experiment under identical conditions and it was verified. Through this comparison and verification, mixing enhancement by cavity could be confirmed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.6
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• pp.477-483
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• 2015

Investigations into cavity flows have been conducted for noise and vibration problems that arise in cavity systems. Cavity systems have been applied in engineering devices and have undergone rapid development in the aerospace industry. Meanwhile, to the author's best knowledge, the cavity on a curved wall has been seldom studied. The present work is conducted to study the flow physics of a cavity mounted on a curved wall. Numerical analysis is performed to investigate the cavity flow. Two variables of sub- and supersonic cavity flows were considered: the radius of curvature of the curved wall (L/R) and the inlet Mach number. The results show that the uniform vortex generated by the cavity flow on the curved wall stabilize the pressure fluctuation as time passes. As the inlet Mach number increases, the pressure fluctuation amplitude increases. The results obtained from the curved wall are compared with those from a straight wall using Rossiter's formula. The Strouhal number of the curved wall is lower than that of the straight wall. Lower Strouhal numbers have been obtained in the present computational fluid dynamics (CFD) results than in the theoretical results using Rossiter's formula.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.1-11
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• 2021

The cavity inside the combustor increases the mixing efficiency of fuel and air by inducing a oscillation of the flow and the recirculation area with a low speed, and enables continuous combustion by maintaining the flame. In this study, the characteristics of the internal flow by change in the shape parameters of the cavity were analyzed through experiments and two-dimensional computational analysis. It was observed that the flow in the supersonic combustor was greatly influenced by various shape parameters of cavity besides L/D. Even with the same L/D, it was confirmed that the flow type varies depending on the depth of the cavity, either open or closed type, and the aft ramp angle of the cavity and the height of the combustor also affect the flow characteristics. As a result, the change in the shape parameters of the cavity had a great influence on the total pressure loss.

• Journal of the Korean Society of Visualization
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• v.9 no.2
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• pp.61-65
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• 2011

Several previous works on rocket nozzle flows have revealed the existence of the transition from FSS to RSS and the occurrence of asymmetric flow associated with the boundary layer separation, which can cause excessive side-loads of the propulsion system. Thus, it is of practical importance to investigate the asymmetric flow behaviors of the propulsion nozzle and to develop its control method. In the present study, the asymmetric flow control method using a cavity system was applied to supersonic nozzle flow. Time-dependent asymmetric flow was experimentally investigated with the rate of change of the nozzle pressure ratio. The results obtained showed that the cavity system installed on nozzle wall would be helpful in fixing the unsteady motions of the boundary layer separation, consequently reducing the possibility of the occurrence of the asymmetric flow.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.76-87
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• 2019

A direct connected test was conducted for a supersonic combustor with a cavity-type flame holder. Liquid hydro-carbon fuel was injected in different types of injectors: inclined and aeroramp injectors, for the flow condition of Mach 4 at an altitude of 20 km. The static pressure on the combustor wall along the axis and the total pressure at the exit of combustor were measured to analyze the combustion characteristics at various fuel flow rates.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.328-331
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• 2008

In order to see the detailed characteristics of model scramjet engine, numerical analysis was performed and compared to the ground test results done by KARI and UQ. Pressure distribution predicted by numerical analysis showed good agreements with test results. Static temperature and pressure distribution explained the mechanisms of cavity flame holder and W-shape cowl which have showed enhancing effects on the supersonic combustion.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.20-21
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• 2006

Three kinds of jet flows encountered in the practical airframe design phase are discussed in this paper. Firstly, the side jet effect on the cavity flow over the flat plate was investigated. Secondly, the aerodynamic modeling of side jet influence on body-tail configuration was presented. Computational study of the similarity parameters was done to minimize the wind tunnel test. Lastly, supersonic jet impingement on a flat plate surrounded by solid walls was simulated numerically for both axi-symmetric and three-dimensional calculations with moving body method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.452-455
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• 2008

Model Scramjet engine is tested with T4 free-piston shock tunnel at University of Queensland, Australia. Basically, test condition is fixed as Mach 7.6 at 31 km altitude. With this condition, variation effects of fuel equivalence ratio, cavity, cowl setting and angle of attack were investigated. In the results, supersonic combustion was observed with low and middle fuel equivalence ratio. At high equivalence ratio, thermal choking was occurred due to the intensive reaction. Cavity and W-shape cowl showed early ignition and enhanced mixing respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.19-26
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• 2011

In order to investigate the effect of fuel injection hole configuration within the scramjet combustor, experiment and quasi-one-dimensional analysis was performed. And the results were compared with experiment and analysis result which were performed in 2008 with same facility and test condition. Fuel injection hole size was decreased and quantity was increased. However the depth of fuel penetration and flow quantity of fuel were maintained. As a test result, combustion performance was increased significantly with no-cavity injector and slightly with plain-cavity. However, combustion performance with zigzag-cavity was decreased.