Investigation of flow characteristics in supersonic combustion ramjet combustor toward improvement of combustion efficiency

2020 ◽  
Vol 45 (1) ◽  
pp. 231-253
Author(s):  
Prasanth P. Nair ◽  
Amsha S ◽  
Abhilash Suryan ◽  
Sandro Nizetic
Keyword(s):  
Flow Characteristics ◽  
Combustion Efficiency ◽  
Supersonic Combustion ◽  
Ramjet Combustor ◽  
Supersonic Combustion Ramjet

Flow Characteristics of Rectangular Liquid Jets Injected Into Low Subsonic Crossflow

2019 ◽  
Author(s):  
M. Tadjfar ◽  
A. Jaberi ◽  
R. Shokri
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Combustion Efficiency ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Aspect Ratios ◽  
Jet Trajectory ◽  
Wide Range ◽  
Circular Holes ◽  
Subsonic Crossflow

Abstract Perpendicular injection of liquid jets into gaseous crossflow is well-known as an effective way to obtain good mixing between liquid fuel and air crossflow. Mostly, injectors with circular holes were used as the standard method of fuel spraying. However, recently a great attention to injectors with non-circular holes has emerged that aims to improve the quality of fuel mixing and consequently combustion efficiency. In the present work, rectangular injectors with different aspect ratios varying from 1 to 4 were experimentally studied. Using a wind tunnel with maximum air velocity of 42 m/s, tests were performed for a wide range of flow conditions including liquid-to-air momentum ratios of 10, 20, 30 and 40. Backlight shadowgraphy and high speed photography were employed to capture the instantaneous physics of the liquid jets discharged into gaseous crossflow. The flow physics of the rectangular liquid jets were investigated by means of flow visualizations. Different regimes of flow breakup including capillary, arcade, bag and multimode were observed for rectangular jets. Moreover, a new technique was used to calculate the trajectory of the liquid jets. It was shown the nozzle’s shape has no significant effect on jet trajectory. Also, the momentum ratio was found to has a profound effect on jet trajectory.

Investigation of the Formation of Microbubbly Liquid Fuel

2009 ◽  
Author(s):  
Emine Celik ◽  
Joseph Katz ◽  
David M. Van Wie
Keyword(s):  
Liquid Fuel ◽  
Gas Bubbles ◽  
Supersonic Combustion ◽  
Short Chain ◽  
Experimental Facility ◽  
Second Stage ◽  
Thermal Pyrolysis ◽  
New Type ◽  
Supersonic Combustion Ramjet ◽  
Long Chain

There are several obstacles encountered during combustion in Supersonic Combustion Ramjet (SCRAMJET) engines such as mixing, ignition, and flame holding. In order to overcome these difficulties, a new type of fuel is generated with the use of combination of two methods namely an effervescent (barbotage) and thermal pyrolysis of the fuel. In the first step of the process, during effervescent method, small gas bubbles are introduced into liquid fuel to improve the spraying characteristics of the fuel. At the second stage, long-chain hydrocarbons are broken down into short-chain hydrocarbons that burn faster. An experimental facility has been designed and developed to study the underlying physics in each process.

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.

scholarly journals Numerical Investigation of the Influence of Injection Scheme on the Ethylene Supersonic Combustion

2014 ◽  
Vol 6 ◽  
pp. 124204 ◽  
Author(s):  
Hao Ouyang ◽  
Weidong Liu ◽  
Mingbo Sun
Keyword(s):  
Heat Release ◽  
Separation Zone ◽  
Injection Pressure ◽  
Combustion Efficiency ◽  
Supersonic Combustion ◽  
Recovery Coefficient ◽  
Starting Point ◽  
Combustion Flow ◽  
Inlet Unstart ◽  
Pressure Recovery Coefficient

Ethylene supersonic combustion flow field in different injection schemes was studied numerically in the flight Mach 4. The results show that injection pressure has significant influence on the location of the separation zone and the heat release region, but the starting point of the separation region was mostly influenced by the heat release rather than by the injection pressure; the combustion efficiency of the injection schemes including two injection points is higher than that of three injection points, while the total pressure recovery coefficient of the former injection schemes is lower than the latter; excessive ethylene injected in upstream will lead to the change of free-stream flow conditions, which behaves as the inlet unstart in practical application; more ethylene could be injected in downstream to avoid the problem; on the condition of avoiding thermal choke in isolator, it is more advantageous that injection points were arranged more closely to the starting point of separation zone in upside and to the front of the cavity in downside.

Finite Rate Chemistry Large-Eddy Simulation of Self-Ignition in Supersonic Combustion Ramjet

AIAA Journal ◽  
2010 ◽  
Vol 48 (3) ◽  
pp. 540-550 ◽  
Author(s):  
M. Berglund ◽  
E. Fedina ◽  
C. Fureby ◽  
J. Tegnér ◽  
V. Sabel'nikov
Keyword(s):  
Large Eddy Simulation ◽  
Supersonic Combustion ◽  
Finite Rate ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Supersonic Combustion Ramjet

Optimize Vane Length to Improve In-Cylinder Air Characteristic of CI Engine Using Higher Viscous Fuel

2013 ◽  
Vol 393 ◽  
pp. 293-298 ◽  
Author(s):  
Idris Saad ◽  
Saiful Bari
Keyword(s):  
Internal Combustion Engines ◽  
Air Flow ◽  
Flow Characteristics ◽  
Internal Combustion ◽  
Combustion Efficiency ◽  
Cylinder Pressure ◽  
Ic Engine ◽  
Ci Engine ◽  
Ci Engines ◽  
Vane Angle

Environmental issues and the depletion of worldwide crude oil sources have developed the requirement for an alternative fuel to power internal combustion engines. Vegetable oil, waste cooking oil and biodiesel are all renewable, environmentally sustainable and compatible with current Compression Ignition (CI) engines with little to no engine modification necessary. These fuels however have a higher viscosity than conventional petro-diesel and may be referred to as Higher Viscous Fuels (HVF). HVF have reduced in-cylinder combustion efficiency when compared with petro-diesel which reduces the engine performance in terms of output power, torque and fuel efficiency. A possible solution to the reduced efficiency is through the use of a Guide Vane Swirl and Tumble Device (GVSTD). This device when installed in front of the air intake manifold may produce improved air flow characteristics. This improves the efficiency of the evaporation processes and air-fuel mixing and therefore improves overall combustion efficiency. The effect of GVSTDs on in-cylinder air flow was studied using 3D Internal Combustion (IC) engine simulation under motored engine conditions. This was done using ANSYS-CFX. The base model engine was adapted from the Hino W04D model CI engine. The model throughout all simulations was run at a constant speed of 1500 rpm. There are four parameters to consider for GVSTD models; vane length, vane height, vane angle and the number of vanes. For the purpose of this study, the vane height, vane angle and the number of vanes were maintained as constants leaving the vane length as the variable parameter. 11 GVSTD models were simulated each varying from 1.5 to 4.5 times the radius of the intake runner (R) in 0.3R increments. To analyze the air-flow characteristics, the maximum in-cylinder pressure, Turbulence Kinetic Energy (TKE) and velocity were measured. It was found that for the constant values for vane height, vane angle and the number of vanes of 0.2R, 35° twist angle and 4 perpendicularly-arranged respectively, the in-cylinder pressure, TKE and velocity were optimum for the vane lengths of 3.6 to 3.9 times R.

scholarly journals The Effect of Inlet Air Vitiation on Combustion Efficiency

1985 ◽  
Author(s):  
Fan Zuomin ◽  
Jiang Yijun
Keyword(s):  
Test Data ◽  
Calculation Method ◽  
Combustion Efficiency ◽  
Empirical Correlation ◽  
Experimental Results ◽  
Ramjet Combustor ◽  
Stirred Reactor ◽  
Good Agreement

Experimental results of the effect of inlet air vitiation produced by a vitiating preheater on combustion efficiency of a turbojet combustor and a model ramjet combustor are presented in this paper. An empirical correlation and a calculation method based on stirred reactor theory are derived to correct the vitiation effect. Results obtained by means of these two methods are in good agreement with test data.

Inlet air and fuel flow pressure fluctuation effect on supersonic combustion

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
AmirMahdi Tahsini
Keyword(s):  
Shock Wave ◽  
Combustion Chamber ◽  
Pressure Fluctuations ◽  
Combustion Efficiency ◽  
Supersonic Combustion ◽  
Oblique Shock Wave ◽  
Reacting Flow ◽  
Content Type ◽  
Fuel Flow ◽  
Flow Stream

Purpose The purpose of this paper is to analyze the effect of pressure fluctuations on the combustion efficiency of the hydrogen fuel injected into the supersonic oxidizing cross flow. The pressure fluctuations are imposed on inlet air flow and also on the fuel flow stream. Two different situations are considered: the combustion chamber once without and again with the inlet standing oblique shock wave. Design/methodology/approach The pressure fluctuations are imposed on inlet air flow and also on the fuel flow stream. Two different situations are considered: the combustion chamber once without and again with the inlet standing oblique shock wave. The unsteady turbulent reacting flow solver is developed to simulate the supersonic flow field in the combustion chamber with detail chemical kinetics, to predict the time-variation of the combustion efficiency due to the imposed pressure fluctuations. Findings The results show that the response of the reacting flow field depends on both the frequency of fluctuations and the existence of the inlet shock wave. In addition, the inlet standing shock wave has some attenuating role, but the reacting flow shows an amplifying role on imposed oscillations which is also augmented by imposing anti-phase fluctuations on both inlet and fuel flow streams. Originality/value This study is performed to analyze the instabilities in the supersonic combustion which has not been considered before in this manner.

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