CFD Analysis of Scramjet Combustor with Non-Premixed Turbulence Model Using Ramp Injector

2014 ◽  
Vol 555 ◽  
pp. 18-25 ◽  
Author(s):  
Krishna Murari Pandey ◽  
Sukanta Roga
Keyword(s):  
Supersonic Combustion ◽  
Maximum Temperature ◽  
Combustion Model ◽  
Inlet Temperature ◽  
Reacting Flow ◽  
Complete Combustion ◽  
Scramjet Combustor ◽  
Air Inlet ◽  
Fuel Jet ◽  
Combustion Of Hydrogen

This paper presents the supersonic combustion of hydrogen using strut injector along with two-dimensional turbulent non-premixed combustion model with air inlet temperature of 750 0k and vitiated Mach number of 2. In this process, a PDF approach is created and this method needs solution to a high dimensional PDF transport equation. As the combustion of hydrogen fuel is injected from the strut injector, it is successfully used to model the turbulent reacting flow field. It is observed from the present work that, the maximum temperature of 2096 0k occurred in the recirculation area which is produced due to shock wave-expansion and the fuel jet losses concentration and after passing successively through such areas, temperature decreased slightly along the axis. From the maximum mass fraction of OH, it is observed that there is very little amount of OH around 0.0017 were found out after combustion. By providing strut injector, expansion wave is created which causes the proper mixing between the fuel and air that results in complete combustion.

Spray and Emission Characteristics Near Lean Blow Out in a Counter-Swirl Stabilized Gas Turbine Combustor

2006 ◽  
Author(s):  
Jonathan A. Colby ◽  
Suresh Menon ◽  
Jechiel Jagoda
Keyword(s):  
Droplet Diameter ◽  
Reacting Flow ◽  
Gas Turbine Combustor ◽  
Complete Combustion ◽  
Fuel Droplets ◽  
Phase Velocities ◽  
Fuel Jet ◽  
Key Factor ◽  
Flow Features ◽  
Initial Droplet Size

An experimental study of a single, swirl cup burner is carried out to improve understanding of the lean reacting flow field near idle conditions for an annular spray combustor. The counter-swirler is mounted horizontally in a trapezoidal cross-section combustor with quartz plate walls. Liquid fuel, Jet-A, is initially atomized using a simplex nozzle, and then a designed re-atomization occurs from the swirler hardware. Measurements of non-reacting and reacting gas phase velocities enable the direct comparison of critical flow features at various power settings. Droplet diameter and exhaust composition measurements confirm that the initial droplet size is a key factor in emission levels. Smaller droplets in the spray periphery tend to evaporate and burn premixed, while larger droplets in the spray core convect downstream and burn with a sheath-type, non-premixed flame. The presence of small fuel droplets in the spray may ensure more complete combustion and improve combustor stability at lean, low power settings.

Experimental study on the effect of air throttling on supersonic combustion

2016 ◽  
Vol 232 (3) ◽  
pp. 472-480 ◽  
Author(s):  
Ye Tian ◽  
Shunhua Yang ◽  
Baoguo Xiao ◽  
Jialing Le
Keyword(s):  
Experimental Study ◽  
Mass Flux ◽  
Equivalence Ratio ◽  
Flame Stabilization ◽  
Wall Pressure ◽  
Supersonic Combustion ◽  
Reacting Flow ◽  
Flux Rate ◽  
Shock Train ◽  
Scramjet Combustor

The effect of air throttling on supersonic combustion was investigated by experiments in the present paper. Our results indicated that, in the non-reacting flow, a shock train could be generated in the scramjet combustor due to the increased backpressure caused by air throttling, and the wall pressure increased obviously. But when the mass flux rate of air throttling was not large enough, the shock train would oscillate with the flow. In the reacting flow, the flame stabilization was achieved in the combustor without air throttling when the equivalence ratio of kerosene was 0.2 and 0.31, but the flame was blown off when the equivalence ratio of kerosene was 0.45. On the contrary, the kerosene (equivalence ratio: 0.45) was ignited successfully in the combustor with air throttling, and it kept burning all the time in the cases with air throttling −5% (the flux of air throttling was 5% of the inflow flux) and with air throttling −14% (the flux of air throttling was 14% of the inflow flux), but the flame was blown off in the case with air throttling −1.1% after kerosene had burnt 70 ms. The flux of air throttling should be large enough to achieve flame stabilization, and the hydrogen and air throttling should both exist all the time in order to keep the flame burning steadily.

Effects of Droplet Size and Air Preheating on Soot Formation in Turbulent Combustion of Liquid Fuel

2010 ◽  
Author(s):  
Amirmahdi Ghasemi ◽  
Mohammad Moghiman ◽  
Seyed Mohammad Javadi ◽  
Naseh Hosseini
Keyword(s):  
Droplet Size ◽  
Liquid Fuel ◽  
Soot Formation ◽  
Control Volume ◽  
Combustion Model ◽  
Inlet Temperature ◽  
Soot Emission ◽  
Fuel Droplet ◽  
Air Inlet ◽  
Spray Flames

The present study is concerned with the effect of fuel droplet size, air inlet preheating and air swirl number on complex soot process in a turbulent liquid-fuelled combustor. A hybrid Eulerian-Lagrangian method is employed to model the reactive flow-field inside the combustor. Equations governing the gas phase are solved by a control volume based semi-implicit iterative procedure while the time-dependent differential equations for each sizes of the fuel droplets are integrated by a semi-analytic method. The processes leading to soot consist of both formation and combustion. Soot formation is simulated using a two-step model while a finite rate combustion model with eddy dissipation concept is implemented for soot combustion. Also, mathematical models for turbulence, combustion, and radiation are used to take account the effects of these processes. Results reveal the significant influence of liquid fuel droplet size, air inlet temperatures and swirl numbers on soot emission from turbulent spray flames. The predictions show that reduction of spray droplet size and increases of air inlet temperature and swirl numbers considerably, increases soot emission from spray flames.

scholarly journals The Effect of Fuel Injection Location on Supersonic Hydrogen Combustion in a Cavity-Based Model Scramjet Combustor

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 193 ◽  
Author(s):  
Eunju Jeong ◽  
Sean O’Byrne ◽  
In-Seuck Jeung ◽  
A. F. P. Houwing
Keyword(s):  
Equivalence Ratio ◽  
Fuel Injection ◽  
Flow Direction ◽  
Flame Structure ◽  
Flow Characteristics ◽  
Supersonic Combustion ◽  
Reacting Flow ◽  
Total Enthalpy ◽  
Scramjet Combustor ◽  
Injection Location

Supersonic combustion experiments were performed using three different hydrogen fuel-injection configurations in a cavity-based model scramjet combustor with various global fuel–air equivalence ratios. The configurations tested were angled injection at 15° to the flow direction upstream of the cavity, parallel injection from the front step, and upstream injection from the rear ramp. Planar laser-induced fluorescence of the hydroxyl radical and time-resolved pressure measurements were used to investigate the flow characteristics. Angled injection generated a weak bow shock in front of the injector and recirculation zone to maintain the combustion as the equivalence ratio increased. Parallel and upstream injections both showed similar flame structure over the cavity at low equivalence ratio. Upstream injection enhanced the fuel diffusion and enabled ignition with a shorter delay length than with parallel injection. The presence of a flame near the cavity was determined while varying the fuel injection location, the equivalence ratio, and total enthalpy of the air flow. The flame characteristics agreed with the correlation plot for the stable flame limit of non-premixed conditions. The pressure increase in the cavity for reacting flow compared to non-reacting flow was almost identical for all three configurations. More than 300 mm downstream of the duct entrance, averaged pressure ratios at low global equivalence ratio were similar for all three injection configurations.

Effect of Secondary Air Configuration in Gas Turbine Combustor Firing Natural Gas

2014 ◽  
Author(s):  
Akram Zaid ◽  
Ahmed Farag ◽  
Tarek M. Belal
Keyword(s):  
Natural Gas ◽  
Combustion Model ◽  
Reacting Flow ◽  
Gas Turbine Combustor ◽  
Air Inlet ◽  
Sheer Stress ◽  
Axial Temperature ◽  
Inlet Conditions ◽  
Secondary Air ◽  
Omega Model

The effect of secondary air inlet conditions on natural gas combustor is investigated numerically. Secondary air inlet conditions include its amount, position, total number of inlet ports and its arrangement along the combustor. The secondary air is introduced normally through inlet ports at different levels along the combustor. Each level includes a number of ports distributed around the combustor periphery. The number of ports levels varied from four up to sixteen and the number of ports in each level varied from four up to sixteen ports. Thus, the total number of ports varied from 16 up to 256. The combustor used has an air swirler at its upstream. Primary air, secondary air and fuel lines are also included. The sheer-stress transport (SST) k-omega model was used to simulate the turbulent isothermal flow and the non-premixed combustion model was used to simulate the turbulent reacting flow. For validating the model, a comparison between the measured and the calculated axial temperature distribution is made which show a reasonable agreement. Primary air swirl number of 0.87 and air to fuel ratio of 30 are used in this study. Secondary air leads to a decrease in flame size. For secondary to primary air ratio (SPAR) greater than 0.3, the flame became narrower in diameter and shorter in length. For certain secondary air configuration, NO, CO, CO2 are decreased with secondary air and are further decreased when increasing the value of SPAR.

Effects of pylon geometry on mixing enhancement in a scramjet pylon-cavity flameholder

2020 ◽  
Vol 124 (1278) ◽  
pp. 1262-1280
Author(s):  
A. Oamjee ◽  
R. Sadanandan
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Supersonic Combustion ◽  
Total Pressure Loss ◽  
Absolute Pressure ◽  
Mixing Efficiency ◽  
Mixing Enhancement ◽  
Scramjet Combustor ◽  
Fuel Jet ◽  
Jet Penetration

ABSTRACTNumerical investigation of the effect of pylon geometry within a pylon-cavity aided Supersonic Combustion Ramjet (SCRAMJET) combustor on mixing enhancement, flame-holding capability, fuel jet penetration and total pressure loss are conducted in the current study. RANS equations for compressed real gas are solved by coupled, implicit, second-order upwind solver. A two-equation SST model is used for turbulence modelling. Validation of the computational model is performed with the help of experimental data collected using surface pressure taps, Schlieren flow visualisation and particle image velocimetry (PIV). The study uses four distinct pylon geometry cases, which include the baseline geometry. Sonic injection of hydrogen fuel through a 1mm diameter hole at 2mm downstream of the pylon rear face along the axis of the test section floor is performed for every case. A crossflow of Mach number 2.2 at four bar absolute pressure and standard atmospheric temperature is maintained. A comparative study of mixing efficiency, total pressure loss, fuel jet penetration and fuel plume area fraction for the different cases evaluate the mixing performance. The simulations show that the Pylon 2 case gives a significant improvement in the performance parameters compared to the other geometries. It is observed that mixing efficiency and fuel jet penetration capability of the system are highly dependent on the streamwise vortex within the flameholder.

scholarly journals Thermal Simulation of Power Lithium-ion Battery Module

2021 ◽  
Vol 233 ◽  
pp. 01028
Author(s):  
Fancong Zeng ◽  
Zhijiang Zuo ◽  
Han Li ◽  
Libo Pan
Keyword(s):  
Temperature Distribution ◽  
Lithium Ion Battery ◽  
Thermal Management ◽  
Lithium Ion ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
Design And Optimization ◽  
Air Inlet ◽  
Cfd Method ◽  
Battery Module

Thermal management of power lithium-ion battery modules is very important to avoid thermal problems such as overheating and out of control, the study of thermal behavior of battery modules can provide guidance for the design and optimization of modules and thermal management. In this paper, a 3d thermal model of the power lithium-ion battery module is established based on STARCCM+ by using computational fluid dynamics (CFD) method, and a grid independence simulation test is used to determine the number of grids, the temperature distribution is analyzed under the condition of 1C charge current. The research results show that the internal temperature rises gradually with the charge going on, the temperature distribution of the cells is basically symmetrical. When the heat transfer coefficient is 5W/(m2⋅K) and the natural convective air inlet temperature is 300K, the module temperature uniformity is good. But because of the maximum temperature slightly higher than the temperature of thermal runaway, additional cooling methods need to be considered to cool the battery.

scholarly journals Multi-Scale Multi-Field Coupled Analysis of Power Battery Pack Based on Heat Pipe Cooling

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 696
Author(s):  
Ye Liu ◽  
Tao Jiang ◽  
Yanping Zheng ◽  
Jie Tian ◽  
Zheshu Ma
Keyword(s):  
Heat Pipe ◽  
Temperature Difference ◽  
Battery Pack ◽  
Dynamics Simulation ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
Multi Scale ◽  
Field Coupling ◽  
Air Inlet ◽  
Power Battery

Based on the study of the relationship between micro and macro parameters in the actual microstructure of the electrodes, a new multi-scale multi-field coupling model of battery monomer is established and the heat generation rate of the battery is obtained by detailed numerical simulation. According to the parameters of a certain electric vehicle and battery selected, the structure of the power battery pack and heat pipe cooling system is designed. Through multi-field coupling computational fluid dynamics simulation, the temperature difference of the battery pack is gained. By changing the fin spacing, the cooling scheme of the heat pipe is optimized, which ensures that the temperature difference is less than 5 K and the maximum temperature of the battery system is 306.26 K. It is found that increasing the discharge rate, the temperature difference increases rapidly. Increasing the air inlet velocity can improve the thermal uniformity of the battery pack, but changing the air inlet temperature only determines the range of temperature, it cannot improve the thermal uniformity. The method proposed and results gained can provide a reference for the research of heat management systems with heat pipe of lithium-ion power battery pack for vehicles.

scholarly journals Microencapsulation ofβ-Carotene by Spray Drying: Effect of Wall Material Concentration and Drying Inlet Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Luiz C. Corrêa-Filho ◽  
Maria M. Lourenço ◽  
Margarida Moldão-Martins ◽  
Vítor D. Alves
Keyword(s):  
Antioxidant Activity ◽  
Spray Drying ◽  
Encapsulation Efficiency ◽  
Fruits And Vegetables ◽  
Wall Material ◽  
Inlet Temperature ◽  
Carotene Content ◽  
Arabic Gum ◽  
Air Inlet ◽  
Adverse Environmental Conditions

Carotenoids are a class of natural pigments found mainly in fruits and vegetables. Among them,β-carotene is regarded the most potent precursor of vitamin A. However, it is susceptible to oxidation upon exposure to oxygen, light, and heat, which can result in loss of colour, antioxidant activity, and vitamin activity. Thus, the objective of this work was to study the microencapsulation process ofβ-carotene by spray drying, using arabic gum as wall material, to protect it against adverse environmental conditions. This was carried out using the response surface methodology coupled to a central composite rotatable design, evaluating simultaneously the effect of drying air inlet temperature (110-200°C) and the wall material concentration (5-35%) on the drying yield, encapsulation efficiency, loading capacity, and antioxidant activity. In addition, morphology and particles size distribution were evaluated. Scanning electron microscopy images have shown that the particles were microcapsules with a smooth surface when produced at the higher drying temperatures tested, most of them having a diameter lower than 10μm. The conditions that enabled obtaining simultaneously arabic gum microparticles with higherβ-carotene content, higher encapsulation efficiency, and higher drying yield were a wall material concentration of 11.9% and a drying inlet temperature of 173°C. The systematic approach used for the study ofβ-carotene microencapsulation process by spray drying using arabic gum may be easily applied for other core and wall materials.

Rough Air-Soft Elastohydrodynamic Lubrication

2013 ◽  
Vol 420 ◽  
pp. 30-35
Author(s):  
Khanittha Wongseedakaew ◽  
Jesda Panichakorn
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Modulus Of Elasticity ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Multilevel Methods ◽  
Inlet Temperature ◽  
Film Pressure ◽  
Air Inlet ◽  
Air Film

This paper presents the effects of rough surface air-soft elastohydrodynamic lubrication (EHL) of rollers for soft material under the effect of air molecular slip. The time independent modified Reynolds equation and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel methods were used to obtain the film pressure profiles and film thickness in the contact region. The effects of amplitude of surface roughness, modulus of elasticity and air inlet temperature are examined. The simulation results showed surface roughness has effect on film thickness but it little effect to air film pressure. When the amplitude of surface roughness and modulus of elasticity increased, the air film thickness decreased but air film pressure increased. However, the air inlet temperature increased when the air film thickness increased.

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