Journal articles: 'Two phase flow combustion'

1

Tolpadi, A. K. "Calculation of Two-Phase Flow in Gas Turbine Combustors." Journal of Engineering for Gas Turbines and Power 117, no. 4 (October 1, 1995): 695–703. http://dx.doi.org/10.1115/1.2815455.

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A method is presented for computing steady two-phase turbulent combusting flow in a gas turbine combustor. The gas phase equations are solved in an Eulerian frame of reference. The two-phase calculations are performed by using a liquid droplet spray combustion model and treating the motion of the evaporating fuel droplets in a Lagrangian frame of reference. The numerical algorithm employs nonorthogonal curvilinear coordinates, a multigrid iterative solution procedure, the standard k-ε turbulence model, and a combustion model comprising an assumed shape probability density function and the conserved scalar formulation. The trajectory computation of the fuel provides the source terms for all the gas phase equations. This two-phase model was applied to a real piece of combustion hardware in the form of a modern GE/SNECMA single annular CFM56 turbofan engine combustor. For the purposes of comparison, calculations were also performed by treating the fuel as a single gaseous phase. The effect on the solution of two extreme situations of the fuel as a gas and initially as a liquid was examined. The distribution of the velocity field and the conserved scalar within the combustor, as well as the distribution of the temperature field in the reaction zone and in the exhaust, were all predicted with the combustor operating both at high-power and low-power (ground idle) conditions. The calculated exit gas temperature was compared with test rig measurements. Under both low and high-power conditions, the temperature appeared to show an improved agreement with the measured data when the calculations were performed with the spray model as compared to a single-phase calculation.

2

Klose, G., R. Schmehl, R. Meier, G. Maier, R. Koch, S. Wittig, M. Hettel, W. Leuckel, and N. Zarzalis. "Evaluation of Advanced Two-Phase Flow and Combustion Models for Predicting Low Emission Combustors." Journal of Engineering for Gas Turbines and Power 123, no. 4 (October 1, 2000): 817–23. http://dx.doi.org/10.1115/1.1377010.

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The development of low-emission aero-engine combustors strongly depends on the availability of accurate and efficient numerical models. The prediction of the interaction between two-phase flow and chemical combustion is one of the major objectives of the simulation of combustor flows. In this paper, predictions of a swirl stabilized model combustor are compared to experimental data. The computational method is based on an Eulerian two-phase model in conjunction with an eddy dissipation (ED) and a presumed-shape-PDF (JPDF) combustion model. The combination of an Eulerian two-phase model with a JPDF combustion model is a novelty. It was found to give good agreement to the experimental data.

3

Som, S. K., and N. Y. Sharma. "Energy and Exergy Balance in the Process of Spray Combustion in a Gas Turbine Combustor." Journal of Heat Transfer 124, no. 5 (September 11, 2002): 828–36. http://dx.doi.org/10.1115/1.1484393.

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A theoretical model of exergy balance based on availability transfer and flow availability in the process of spray combustion in a gas turbine combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions, for fuels with different volatilities. The velocity, temperature and concentration fields in the combustor, required for the evaluation of the flow availabilities and process irreversibilities, have been computed numerically from a two phase separated flow model of spray combustion. The total thermodynamic irreversibility in the process of spray combustion has been determined from the difference in the flow availability at inlet and outlet of the combustor. The irreversibility caused by the gas phase processes in the combustor has been obtained from the entropy transport equation, while that due to the inter-phase transport processes has been obtained as a difference of gas phase irreversibilities from the total irreversibility. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions for fuels with different volatilities has been made to throw light on the trade off between the effectiveness of combustion and the lost work in the process of spray combustion in a gas turbine combustor.

4

Lin, Jih Lung. "Two-phase flow effect on hybrid rocket combustion." Acta Astronautica 65, no. 7-8 (October 2009): 1042–57. http://dx.doi.org/10.1016/j.actaastro.2009.03.020.

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Zhang, Qun, Hua Sheng Xu, Tao Gui, Shun Li Sun, Yue Wu, and Dong Bo Yan. "Investigation on Reaction Flow Field of Low Emission TAPS Combustors." Applied Mechanics and Materials 694 (November 2014): 45–48. http://dx.doi.org/10.4028/www.scientific.net/amm.694.45.

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A twin annular premixing swirler (TAPS) combustor model of low emissions was developed in this study. And computational studies on combustion process in the combustor model were carried out. Standard k-ε Turbulence Model, PDF non-premixed combustion model, Zeldovich thermal NOx formation model and DPM two-phase model were employed. The distributions of some key performance parameters such as gas temperature, flow velocity, concentrations of NOx and CO emissions were obtained and analyzed. At the same time, combustion mechanics inside the TAPS combustor model were investigated. The computational results indicated that the TAPS combustor employed in this study does a better job of improving key combustion performances such as combustion efficiency, total pressure recovery and outlet temperature distribution factor, and reducing NOx and CO emissions at the same time.

6

Chan, S. H., and M. M. M. Abou-Ellail. "A Two-Fluid Model for Reacting Turbulent Two-Phase Flows." Journal of Heat Transfer 116, no. 2 (May 1, 1994): 427–35. http://dx.doi.org/10.1115/1.2911415.

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A reacting two-fluid model, based on the solution of separate transport equations for reacting gas-liquid two-phase flow, is presented. New time-mean transport equations for two-phase mixture fraction f and its variance g are derived. The new two-fluid transport equations for f and g are useful for two-phase reacting flows in which phases strongly interact. They are applicable to both submerged and nonsubmerged combustion. A pdf approach to the reaction process is adopted. The mixture fraction pdf assumes the shape of a beta function while the instantaneous thermochemical properties are computed from an equilibrium model. The proposed two-fluid model is verified by predicting turbulent flow structures of an n-pentane spray flame and a nonreacting bubbly jet flow for which experimental data exist. Good agreement is found between the predictions and the corresponding experimental data.

7

Som, S. K., S. S. Mondal, and S. K. Dash. "Energy and Exergy Balance in the Process of Pulverized Coal Combustion in a Tubular Combustor." Journal of Heat Transfer 127, no. 12 (July 25, 2005): 1322–33. http://dx.doi.org/10.1115/1.2101860.

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A theoretical model of exergy balance, based on availability transfer and flow availability, in the process of pulverized coal combustion in a tubular air-coal combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions. The velocity, temperature, and concentration fields required for the evaluation of flow availability have been computed numerically from a two-phase separated flow model on a Eulerian-Lagrangian frame in the process of combustion of pulverized coal particles in air. The total thermodynamic irreversibility in the process has been determined from the difference in the flow availability at the inlet and outlet of the combustor. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions, such as inlet pressure and temperature of air, total air flow rate and inlet air swirl, initial mean particle diameter, and length of the combustor, has been provided to shed light on the trade-off between the effectiveness of combustion and the lost work in the process of pulverized coal combustion in a tubular combustor.

8

Zhang, Xiang Yu, Guo Qiang He, Pei Jin Liu, and Jiang Li. "Heat Flux Measurement Method of Two-Phase Flow in SRM." Applied Mechanics and Materials 152-154 (January 2012): 883–88. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.883.

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Accurate information on heat transfer data of combustion products in the solid rocket motor chamber is a crucial prerequisite for the engine thermal protection. A measurement technique was well developed to acquire steady-state heat flux data of two-phase flow and was used successfully in the hostile environment. Experimental heat flux measurement has been obtained with an innovative designed instrument by simulating the flow field of complex charging configuration. The total heat flux of combustion products in the chamber was brought away by the coolant and calculated by its enthalpy rise in this device. The data could be used to analyze the heat transfer phenomena in SRMs and provide boundary condition for establishing insulation erosion model.

9

Hsiao Tzu, Chang, Hourng Lih Wu, and Lai Chen Chien. "Nonequilibrium hydrogen combustion in one- and two-phase supersonic flow." International Communications in Heat and Mass Transfer 24, no. 3 (May 1997): 323–35. http://dx.doi.org/10.1016/s0735-1933(97)00018-3.

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10

Ahmad Fuad Abdul Rasid and Yang Zhang. "Combustion Phases of Evaporating Neat Fuel Droplet." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 96, no. 1 (July 6, 2022): 60–69. http://dx.doi.org/10.37934/arfmts.96.1.6069.

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The combustion characteristics of fuel spray can be examined at a basic level by a fuel droplet combustion study. Evaporation processes of a fuel droplet involves few combustion phases mainly heating, boiling and disruptive phase. The transition of phases is found to be caused by two transient combustion process; mainly droplet heating and fuel vapour accumulation. The duration of combustion phases of tested neat fuel droplet in the present work is found to be consistent for each fuel. High volatility fuel is found to have the shortest duration of droplet heating and fuel vapour accumulation. Longer duration of boiling phase provides wider range of measureable burning rate to be done on tested fuel droplet. With precise quantitative measurement method conducted in the present work, high measurement repeatability is assured thus enabling the determination of droplet combustion stability categorization with clear definition throughout the lifetime of evaporating neat fuel droplet. Additionally, this paper summarises the common combustion phases involved during the evaporation of a neat fuel droplet.

11

Kim, Meeri. "Simulating the detonation flow field of a two-phase rotating detonation ramjet." Scilight 2022, no. 46 (November 11, 2022): 461103. http://dx.doi.org/10.1063/10.0015147.

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Gao, Xiao, Mao Lei, and Weiwei Xu. "Numerical simulation and improvement of combustor structure in 3D printed sand recycling system." Polish Journal of Chemical Technology 25, no. 4 (December 1, 2023): 19–27. http://dx.doi.org/10.2478/pjct-2023-0034.

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Abstract In this paper, a new combustor with an output of 5 t/h is designed based on a computational particle fluid dynamics (CPFD) model. The flow field simulation is combined with the combustion simulation to analyze the internal two-phase flow, temperature field, and combustion products. The combustor structure was optimized. The simulation results show that the recovery efficiency of the waste sand and the energy utilization of the combustor can be improved under the original structure. The sand bed has a significant effect on flow field characteristics. The increase in particle temperature in the combustor increases the efficiency of waste sand recovery by increasing the height of the sand bed by 50 mm. The utilization rate of natural gas is increased and the economic efficiency is improved. The feasibility of the CPFD method can simulate the flow field characteristics inside the combustor very effectively.

13

Moiseeva, K. M. "COMBUSTION OF ALUMINUM POWDER-AIR SUSPENSION IN A SWIRL FLOW." Eurasian Physical Technical Journal 18, no. 2 (June 11, 2021): 47–55. http://dx.doi.org/10.31489/2021no2/47-55.

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The article is devoted to the numerical solution of the problem of the combustion of powder metal fuel in a combustion chamber with swirling flow. A physico-mathematical model of the flow of an air suspension of aluminum powder in a swirling flow in a cylindrical combustion chamber with a sudden expansion is presented. The physical and mathematical formulation of the problem is based on the approaches of the mechanics of two-phase reacting media. The solution was carried out using the arbitrary discontinuity decay method. The results of a numerical parametric study of the features of the combustion of an air suspension of aluminum powder depending on its composition, the axial flow rate of the mixture at the entrance to the combustion chamber, and the value of the swirl speed are shown.

14

Zhang Peng, Hong Yan-Ji, Ding Xiao-Yu, Shen Shuang-Yan, and Feng Xi-Ping. "Effect of plasma on boron-based two-phase flow diffusion combustion." Acta Physica Sinica 64, no. 20 (2015): 205203. http://dx.doi.org/10.7498/aps.64.205203.

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15

MARGOLIS, STEPHEN B. "FUNDAMENTAL TWO-PHASE-FLOW MODELS OF COMBUSTION IN POROUS ENERGETIC MATERIALS." Combustion Science and Technology 177, no. 5-6 (April 2005): 1183–229. http://dx.doi.org/10.1080/00102200590927049.

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16

Li, Zhengang, Zhancheng Guo, Xuzhong Gong, and Huiqing Tang. "Kinetic characteristics of pulverized coal combustion in the two-phase flow." Energy 55 (June 2013): 585–93. http://dx.doi.org/10.1016/j.energy.2013.04.028.

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17

Markatos, N. C. "Modelling of two-phase transient flow and combustion of granular propellants." International Journal of Multiphase Flow 12, no. 6 (November 1986): 913–33. http://dx.doi.org/10.1016/0301-9322(86)90035-2.

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18

M. Rashad, Mahmoud, Xiao Bing Zhang, Hazem El Sadek, and Cheng Cheng. "Two-Phase Flow Interior Ballistics Model of Naval Large Caliber Guided Projectile Gun System." Applied Mechanics and Materials 465-466 (December 2013): 592–96. http://dx.doi.org/10.4028/www.scientific.net/amm.465-466.592.

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The two-phase flow mathematical model for the solid granular propellant and its products of combustion inside large caliber naval gun guided projectile system (NGGPS) during interior ballistic cycle is presented. The model includes the governing equations of mass, momentum and energy for both phases as well as the constitutive laws. The discharged combustion products from the igniter vent-holes into the chamber are acquired by incorporation in the model the two-phase flow model of the bayonet igniter. The system of equations of the two-phase flow model is solved using the second order accurate Maccromacks technique. A one dimensional model introduced by G.A. Sod (shock tube) is utilized to test the ability of Maccromacks algorithm in solving the initial boundary value problem (IBVP) for the system of equations with shock wave behavior. The numerical method is verified by using an exact solution of a test problem. The moving control volume conservation method (MCVC) is used to handle the moving boundary as well as a self-adapting method was used to expand the computational domain in order to follow the movement of the projectile down the gun bore. The numerical results are validated with experimental data. The interior ballistics performance of a 130 mm naval guided projectile gun system is closely predicted using the presented two-phase flow model and the numerical code.

19

Hwang, Donghyun, and Kyubok Ahn. "Experimental Study on Dynamic Combustion Characteristics in Swirl-Stabilized Combustors." Energies 14, no. 6 (March 14, 2021): 1609. http://dx.doi.org/10.3390/en14061609.

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An experimental study was performed to investigate the combustion instability characteristics of swirl-stabilized combustors. A premixed gas composed of ethylene and air was burned under various flow and geometric conditions. Experiments were conducted by changing the inlet mean velocity, equivalence ratio, swirler vane angle, and combustor length. Two dynamic pressure sensors, a hot-wire anemometer, and a photomultiplier tube were installed to detect the pressure oscillations, velocity perturbations, and heat release fluctuations in the inlet and combustion chambers, respectively. An ICCD camera was used to capture the time-averaged flame structure. The objective was to understand the relationship between combustion instability and the Rayleigh criterion/the flame structure. When combustion instability occurred, the pressure oscillations were in-phase with the heat release oscillations. Even if the Rayleigh criterion between the pressure and heat release oscillations was satisfied, stable combustion with low pressure fluctuations was possible. This was explained by analyzing the dynamic flow and combustion data. The root-mean-square value of the heat release fluctuations was observed to predict the combustion instability region better than that of the inlet velocity fluctuations. The bifurcation of the flame structure was a necessary condition for combustion instability in this combustor. The results shed new insight into combustion instability in swirl-stabilized combustors.

20

Sultanov, T. S., and G. A. Glebov. "Numerical Computation of Specific Impulse and Internal Flow Parameters in Solid Fuel Rocket Motors with Two-Phase Сombustion Products." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 3 (138) (September 2021): 98–107. http://dx.doi.org/10.18698/0236-3941-2021-3-98-107.

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Eulerian --- Lagrangian method was used in the Fluent computational fluid dynamics system to calculate motion of the two-phase combustion products in the solid fuel rocket motor combustion chamber and nozzle. Condensed phase is assumed to consist of spherical particles with the same diameter, which dimensions are not changing along the motion trajectory. Flows with particle diameters of 3, 5, 7, 9, and 11 μm were investigated. Four versions of the engine combustion chamber configuration were examined: with slotted and smooth cylindrical charge channels, each with external and submerged nozzles. Gas flow and particle trajectories were calculated starting from the solid fuel surface and to the nozzle exit. Volumetric fields of particle concentrations, condensed phase velocities and temperatures, as well as turbulence degree in the solid propellant rocket engine flow duct were obtained. Values of particles velocity and temperature lag from the gas phase along the nozzle length were received. Influence of the charge channel shape, degree of the nozzle submersion and of the condensate particles size on the solid propellant rocket engine specific impulse were determined, and losses were estimated in comparison with the case of ideal flow

21

Liu, De Song, Hong Fu Qiang, Xue Li Xia, and Guang Wang. "Numerical Simulation of the Two-Phase Turbulent Combustion Flow in the Multicomponent Propellant Rocket Engine." Advanced Materials Research 452-453 (January 2012): 1334–38. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1334.

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The numerical simulation, based on computational fluid dynamics methodology, has been performed to study the two-phase turbulent combustion flow in rocket engine using non-metallized multicomponent propellant. A reduced reaction mechanism is developed for modelling combustion of fuel droplets in the absence of metal. Gas governing equations are two dimensional axisymmetric N-S equations in Eulerian coordinates. The trajectory model is adopted to analyse the droplet-phase including the droplet collision, breakup and evaporation. The gas flow is influenced by the droplets by adding source term to N-S equations. The reliability of the simulation programme is validated by comparing numerical simulation result with engine test data.

22

Askari Mahvelati, Ehsan, Mario Forcinito, Laurent Fitschy, and Arthur Maesen. "Three-Dimensional CFD Model Development and Validation for Once-Through Steam Generator (OTSG): Coupling Combustion, Heat Transfer and Steam Generation." ChemEngineering 6, no. 2 (March 14, 2022): 23. http://dx.doi.org/10.3390/chemengineering6020023.

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The current research studies the coupled combustion inside the furnace and the steam generation inside the radiant and convection tubes through a typical Once-Through Steam Generator (OTSG). A 3-D CFD model coupling the combustion and the two-phase flow was developed to model the entire system of OTSG. Once the combustion simulation was converged, the results were compared to field data showing a convincing agreement. The CFD analysis provides the detailed flow behavior inside the combustion chamber and the stack, as well as the two-phase flow steam generation process in the radiant and convective sections. The flame shape and orientation, the velocity, the species, and the temperature distribution at the various parts of the furnace, as well as the steam generation and the steam distribution inside the pipes were investigated using the developed CFD model

23

Xiao, Yumin, R. S. Amano, Timin Cai, and Jiang Li. "New Method to Determine the Velocities of Particles on a Solid Propellant Surface in a Solid Rocket Motor." Journal of Heat Transfer 127, no. 9 (April 19, 2005): 1057–61. http://dx.doi.org/10.1115/1.1999652.

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Use of aluminized composite solid propellants and submerged nozzles are common in solid rocket motors (SRM). Due to the generation of slag, which injects into a combusted gas flow, a two-phase flow pattern is one of the main flow characteristics that need to be investigated in SRM. Validation of two-phase flow modeling in a solid rocket motor combustion chamber is the focus of this research. The particles’ boundary conditions constrain their trajectories, which affect both the two-phase flow calculations, and the evaluation of the slag accumulation. A harsh operation environment in the SRM with high temperatures and high pressure makes the measurement of the internal flow field quite difficult. The open literature includes only a few sets of experimental data that can be used to validate theoretical analyses and numerical calculations for the two-phase flow in a SRM. Therefore, mathematical models that calculate the trajectories of particles may reach different conclusions mainly because of the boundary conditions. A new method to determine the particle velocities on the solid propellant surface is developed in this study, which is based on the x-ray real-time radiography (RTR) technique, and is coupled with the two-phase flow numerical simulation. Other methods imitate the particle ejection from the propellant surface. The RTR high-speed motion analyzer measures the trajectory of the metal particles in a combustion chamber. An image processing software was developed for tracing a slug particle path with the RTR images in the combustion chamber, by which the trajectories of particles were successfully obtained.

24

Dong, Ming, MaoZhao Xie, and SuFen Li. "Numerical study on turbulent two-phase flow in porous medium combustion chamber." Science in China Series E: Technological Sciences 52, no. 6 (May 15, 2009): 1511–20. http://dx.doi.org/10.1007/s11431-009-0170-9.

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25

Hao, Guancheng, Bowen Pang, Qilin Zhang, Fei Cui, Sijia Sun, and Shuo Liu. "Flame synchronization and flow field analysis of double candles." Journal of Physics: Conference Series 2247, no. 1 (April 1, 2022): 012030. http://dx.doi.org/10.1088/1742-6596/2247/1/012030.

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Abstract Flame instability is an interesting topic in combustion science, and it is also of great practical significance for designing high-performance burners. In recent years, the synchronization phenomenon caused by a pair of coupled candles has aroused widespread attention, among which in-phase and anti-phase are two notable examples. In order to understand the flow structure of the flashing flame and the reasons for the synchronization of the flame oscillator, COMSOL flow field analysis technology and MATLAB grey analysis technology were used to analyze the flow field of candles in three combustion states and the change of candle combustion state respectively. By analyzing the flow structure of flashing flame, the reasons of different burning states of candles are explained. Moreover, the experimental and numerical simulation results show that the in-phase mode is characterized by the symmetrical formation of vortex concerning the centerline of two groups of flames, and the flames are vertically stretched under the vortex action. The characteristic of the anti-phase mode is that the vortex alternately forms asymmetrically concerning the centerline of two groups of flames, and the non-uniformity and asymmetry of the vortex lead to the instability of the flame surface. The characteristic of the incoherent mode is that the vortices generated by the two candle groups no longer act on each other, and the airflow field between the two candle groups remains approximately unchanged.

26

Dobrego, K. V., and I. A. Koznacheev. "Numerical Simulation of Two-Phase System of “Combustible Liquid – Solid Fuel” Combustion in a Fixed Bed." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, no. 3 (June 3, 2019): 247–63. http://dx.doi.org/10.21122/1029-7448-2019-62-3-247-263.

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Investigation of combustion of complex heterogeneous systems and particularly of twophase “combustible liquid – solid fuel” systems is topical because of the need to improve combustion of multicomponent and non-standard fuels as well as for resolution of specific ecological problems. The qualitative and quantitative peculiarities of combustion of two model combustible systems, notionally corresponding to the “sawdust – oil” and “wood chips – oil” mixtures are investigated numerically. The main peculiarity of the systems is volatility of the fluid component, being gaseous-flow driven inside porous media. A one-dimensional plain problem of combustion of compact layer with the ignition from the bottom and from the upper side is considered. It is demonstrated that due to low gas permeability of the fine-dispersed solid matrix (sawdust), air flow velocity is relatively low which results in slow formation of the combustion front (the characteristic time is tens of minutes). In case of coarse solid phase (wood chips), airflow rate is higher and corresponding time of temperature fronts formation is smaller (a few minutes). Both for the cases of fine-dispersed and coarse particles solid matrix phase, when set on fire from below, the fluid component is evacuated from the hot zone before the combustion front is formed. Since that, the main characteristics of the temperature front dynamics correspond to “dry” fuel system. In case of upper side ignition the combustion wave is formed at the time of the order of 100 s (when the used magnitudes of parameters are being used again), then it spreads downstream of the layer, accompanied by incomplete oxidation of solid fuel and complete combustion of oxygen. The effect of incomplete solid fuel combustion was noted earlier in the investigations of combustion of lean coal layer and some other systems. The velocity of the combustion wave propagation does not differ much for the cases of upper side and bottom side ignition. But the time of establishing the quasi-stationary velocity of the front to the steady-state value at the initial stage is much less in case of bottom side ignition. The results obtained by the authors can be utilized for optimization of multi-phase fuels combustion in compact layer, the regime parameters of in-situ combustion method of oil recovery increase as well as for improvement of some specific chemical processes.

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Wang, Bei, Yi Xie, and Jian Guo Xiong. "Gasify Micro-Oil Ignition Technology Based on Level Set Methods." Advanced Materials Research 497 (April 2012): 387–91. http://dx.doi.org/10.4028/www.scientific.net/amr.497.387.

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In order to improve the Micro-oil ignition and low fuel load stable combustion in the thermal power system, the standard k-ε model is used in the analysis of flow field for studying the character of the mixture of coal particles, oil and gas mixture. The trajectories of two-phase flow are simulated by the Level Set Methods (LSM). The results describe the velocity distribution of the X-axis of the two-phase flow, concentration and track of coal particles, the thermal distribution of mixed fluid in the combustion chamber. It provides a theoretical basis for the further study of Micro-oil ignition technology

28

Ren, Zhao Xin, Bing Wang, and Hui Qiang Zhang. "Large Eddy Simulation of Two-Phase Mixing Layer Flows in the Scramjet." Applied Mechanics and Materials 249-250 (December 2012): 428–33. http://dx.doi.org/10.4028/www.scientific.net/amm.249-250.428.

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To study the dispersion of fuel droplets in the supersonic flow and reveal the momentum and heat exchanges between two phases, a large eddy simulation (LES) and particle Lagrangian tracking model were employed to numerically simulate two-phase mixing layer flows, using the one-way coupling method. The velocity fluctuation disturbances were added to inspire the flow instabilities. The motions of droplets in different diameters and droplets’ response to the large scale eddies were analyzed. The results indicated that droplets of 1micro diameter below are corresponded with the motions of coherent vortexes in the mixing layer. The more intense momentum and heat exchange are performed with decreasing the droplet’s diameter. The well mixing of fuel droplets in turbulence would make the combustion preparedness more sufficient. The research conclusions are of important academic value for further analyzing the two-phase dynamics in the scramjet.

29

Ha, M. Y. "A Numerical Study of Droplet Evaporation and Combustion in the Presence of an Oscillating Flow." Journal of Energy Resources Technology 119, no. 2 (June 1, 1997): 109–19. http://dx.doi.org/10.1115/1.2794974.

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The two-dimensional, unsteady, laminar conservation equations for mass, momentum, energy, and species transport in the gas phase are solved numerically in spherical coordinates in order to study heat and mass transfer, and combustion around a single spherical droplet. The droplet mass, momentum, and energy equations are also solved simultaneously with the gas phase equations in order to investigate the effects of droplet entrainment and heating in the oscillating flow with and without a steady velocity. The numerical solution for the case of single droplet combustion gives the droplet diameter and temperature variation as well as the gas phase velocity, temperature, and species concentrations as a function of time. The effects of frequency, amplitude of oscillating flow, and velocity ratio of oscillating flow amplitude to the steady velocity on droplet combustion are also investigated. The droplet burning history is not governed by the d2-law in the presence of oscillating flow, unlike the case of quiescent ambient conditions.

30

Raju, M. S., and W. A. Sirignano. "Spray Computations in a Centerbody Combustor." Journal of Engineering for Gas Turbines and Power 111, no. 4 (October 1, 1989): 710–18. http://dx.doi.org/10.1115/1.3240317.

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A hybrid Eulerian–Lagrangian method is employed to model the reactive flow field of a centerbody combustor. The unsteady two-dimensional gas-phase equations are represented in Eulerian coordinates and liquid-phase equations are formulated in Lagrangian coordinates. The gas-phase equations based on the conservation of mass, momentum, and energy are supplemented by turbulence and combustion models. The vaporization model takes into account the transient effects associated with the droplet heating and liquid-phase internal circulation. The integration scheme is based on the TEACH algorithm for gas-phase equations, the Runge-Kutta method for liquid-phase equations, and linear interpolation between the two coordinate systems. The calculations show that the droplet penetration and recirculation characteristics are strongly influenced by the gas- and liquid-phase interaction in such a way that most of the vaporization process is confined to the wake region of the centerbody, thereby improving the flame stabilization properties of the flow field.

31

Breuer, Michael, and Michael Alletto. "Two–phase flow predictions of the turbulent flow in a combustion chamber including particle–particle interactions." Journal of Physics: Conference Series 318, no. 5 (December 22, 2011): 052002. http://dx.doi.org/10.1088/1742-6596/318/5/052002.

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32

Zhou, L. X., F. Wang, L. Y. Hu, K. Li, and K. Luo. "A review on studies of a SOM combustion model for single-and-two-phase combustion." International Journal of Heat and Mass Transfer 96 (May 2016): 154–63. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.01.019.

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Nemoda, Stevan, Milica Mladenovic, Milijana Paprika, Dragoljub Dakic, Aleksandar Eric, and Mirko Komatina. "Euler-Euler granular flow model of liquid fuels combustion in a fluidized reactor." Journal of the Serbian Chemical Society 80, no. 3 (2015): 377–89. http://dx.doi.org/10.2298/jsc140130029n.

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The paper deals with the numerical simulation of liquid fuel combustion in a fluidized reactor using a two-fluid Eulerian-Eulerian fluidized bed modeling incorporating the kinetic theory of granular flow (KTGF) to gas and solid phase flow prediction. The comprehensive model of the complex processes in fluidized combustion chamber incorporates, besides gas and particular phase velocity fields? prediction, also the energy equations for gas and solid phase and the transport equations of chemical species conservation with the source terms due to the conversion of chemical components. Numerical experiments show that the coefficients in the model of inter-phase interaction drag force have a significant effect, and they have to be adjusted for each regime of fluidization. A series of numerical experiments was performed with combustion of the liquid fuels in fluidized bed (FB), with and without significant water content. The given estimations are related to the unsteady state, and the modeled time period corresponds to flow passing time throw reactor column. The numerical experiments were conducted to examine the impact of the water content in a liquid fuel on global FB combustion kinetics.

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Cheng, Cheng, and Xiaobing Zhang. "Numerical investigation of two-phase reactive flow with two moving boundaries in a two-stage combustion system." Applied Thermal Engineering 156 (June 2019): 422–31. http://dx.doi.org/10.1016/j.applthermaleng.2019.04.061.

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Epple, Bernd, Woody Fiveland, Bernd Krohmer, Galen Richards, and Ali C. Benim. "ASSESSMENT OF TWO-PHASE FLOW MODELS FOR THE SIMULATION OF PULVERIZED COAL COMBUSTION." Clean Air: International Journal on Energy for a Clean Environment 6, no. 3 (2005): 267–87. http://dx.doi.org/10.1615/interjenercleanenv.v6.i3.50.

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Benim, A. C., B. Epple, and B. Krohmer. "Modelling of pulverised coal combustion by a Eulerian-Eulerian two-phase flow formulation." Progress in Computational Fluid Dynamics, An International Journal 5, no. 6 (2005): 345. http://dx.doi.org/10.1504/pcfd.2005.007067.

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LI, BAOMING, and DANIEL Y. KWOK. "Two-phase flow simulation of plasma-ignited combustion in an energetic fluid bed." Journal of Plasma Physics 70, no. 2 (April 2004): 225–35. http://dx.doi.org/10.1017/s002237780300254x.

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Dodge, F. T., S. T. Green, and J. E. Johnson. "Characterization of Injection Nozzles for Gas-Solid Flow Applications." Journal of Fluids Engineering 113, no. 3 (September 1, 1991): 469–74. http://dx.doi.org/10.1115/1.2909519.

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Laser phase-doppler velocimetry measurements have been used to characterize the particle-gas sprays produced by straight-tube nozzles that simulate idealized fuel injectors for solid fuel combustion systems. Tests were conducted on two nozzle sizes, for two particle sizes, two loading ratios, and two gas velocities. The Reynolds numbers was varied from 9500 to 19000, and the Stokes number from 1.9 to 61.4. It was found that the velocities of the particles in the spray decelerate more slowly, and the velocity profiles are generally more narrow, than for a single-phase free-jet. The turbulence level of the particles in the sprays was found to be less than half the turbulence level of a single-phase free-jet, and the turbulent velocity profiles were not yet fully developed at X = 40D. The hydrodynamic characteristics of the nozzles that are the most important for combustion systems were found to be: (a) the particle spray expands radially at a cone angle of 2° (measured at the radius corresponding to the peak of the particle mass flux distribution); and (b) the nozzle pressure drop and particle mass flow can be related by a correlation that depends on loading ratio, Reynolds number, Stokes number, and the pressure drop coefficient of the nozzle for a single phase flow.

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Biao, Zhou, and Wu Chengkang. "Numerical modeling of 3-D turbulent two-phase flow and coal combustion in a pulverized-coal combustor." Acta Mechanica Sinica 13, no. 3 (August 1997): 193–202. http://dx.doi.org/10.1007/bf02487701.

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Zhang, De Zhi, Ying Ai Jin, De Yuan Su, and Qing Gao. "Numerical Analysis of Flow at Water Jacket of an Internal Combustion Engine." Advanced Materials Research 282-283 (July 2011): 702–5. http://dx.doi.org/10.4028/www.scientific.net/amr.282-283.702.

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With the increasing degree of the enhancement of engine, engine cooling system design is considered particularly important. This paper used an established three-dimensional model of an engine water jacket to study, and used UDF function in the two-phase flow of the CFD, describe the mathematical model and simulation the engine at different operating conditions, and get the water jacket flow rate transfer thermal process. Finally, the results of the relationship between the engine water jacket of boiling heat transfer and flow velocity have been studied, and the importance of using two-phase flow model has been summarized.

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Deniz Canal, Cansu, Erhan Böke, and Ali Cemal Benim. "Numerical analysis of pulverized biomass combustion." E3S Web of Conferences 321 (2021): 01001. http://dx.doi.org/10.1051/e3sconf/202132101001.

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Combustion of pulverized biomass in a laboratory swirl burner is computationally investigated. The two-phase flow is modelled by an Eulerian-Lagrangian approach. The particle size distribution and turbulent particle dispersion are considered. The radiative heat transfer is modelled by the P1 method. For modelling turbulence, different RANS modelling approaches are applied. The pyrolysis of the solid fuel is modelled by a single step mechanism. For the combustion of the volatiles a two-step reaction mechanism is applied. The gas-phase conversion rate is modelled by the Eddy Dissipation Model, combined with kinetics control. The results are compared with measurements.

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Axelbaum, R. L., D. P. DuFaux, C. A. Frey, K. F. Kelton, S. A. Lawton, L. J. Rosen, and S. M. L. Sastry. "Gas-phase combustion synthesis of titanium boride (TiB2) nanocrystallites." Journal of Materials Research 11, no. 4 (April 1996): 948–54. http://dx.doi.org/10.1557/jmr.1996.0119.

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Two techniques are described for synthesizing nanometer-sized TiB2 particles by gas-phase combustion reactions of sodium vapor with TiCl4 and BCl3: a low-pressure, low-temperature burner and a high-temperature flow reactor. Both methods produce TiB2 particles that are less than 15 nm in diameter. The combustion by-product, NaCl, is efficiently removed from the TiB2 by water washing or vacuum sublimation. Material collected from the low-temperature burner and annealed at 1000 °C consists of loosely agglomerated particles 20 to 100 nm in size. Washed material from the high-temperature flow reactor consists of necked agglomerates of 3 to 15 nm particles. A thermodynamic analysis of the Ti/B/Cl/Na system indicates that near 100% yields of TiB2 are possible with appropriate reactant concentrations, pressures, and temperatures.

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Minkov, Leonid, Ernst R. Shrager, and Elizaveta V. Pikushchak. "Propellant Grain with Maximum Combustion Efficiency of Metal." Key Engineering Materials 685 (February 2016): 325–29. http://dx.doi.org/10.4028/www.scientific.net/kem.685.325.

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This paper reports on the ways of allocating the metal particles in the propellant grain of tube cross-sectional type to provide maximum combustion efficiency of metal. Two-dimensional flow field and the burning rate law govern a transport of the burning metal particles. The analytical correlation for the optimum allocation of metal particles in the case-bounded propellant grain of tube cross-sectional type under the assumption of equilibrium two-phase flow is deduced.

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Sattinger, Stanley S., Yedidia Neumeier, Aharon Nabi, Ben T. Zinn, David J. Amos, and Douglas D. Darling. "Sub-Scale Demonstration of the Active Feedback Control of Gas-Turbine Combustion Instabilities." Journal of Engineering for Gas Turbines and Power 122, no. 2 (January 3, 2000): 262–68. http://dx.doi.org/10.1115/1.483204.

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Described are sub-scale tests that successfully demonstrate active feedback control as a means of suppressing damaging combustion oscillations in natural-gas-fueled, lean-premix combustors. The control approach is to damp the oscillations by suitably modulating an auxiliary flow of fuel injected near the flame. The control system incorporates state observer software that can ascertain the frequency, amplitude, and phase of the dominant modes of combustion oscillation, and a sub-scale fuel flow modulator that responds to frequencies well above 1 kHz. The demonstration was conducted on a test combustor that could sustain acoustically coupled combustion instabilities at preheat and pressurization conditions approaching those of gas-turbine engine operation. With the control system inactive, two separate instabilities occurred with combined amplitudes of pressure oscillations exceeding 70 kPa (10 psi). The active control system produced four-fold overall reduction in these amplitudes. With the exception of an explainable control response limitation at one frequency, this reduction represented a major milestone in the implementation of active control. [S0742-4795(00)00702-X]

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Song, Jiajun, Dongyan Han, Qinqin Xu, Dan Zhou, and Jianzhong Yin. "Heat transfer model of two-phase flow across tube bundle in submerged combustion vaporizer." Chinese Journal of Chemical Engineering 27, no. 3 (March 2019): 613–19. http://dx.doi.org/10.1016/j.cjche.2018.06.032.

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Sharapov, A. I., A. A. Chernykh, and A. V. Peshkova. "Supersonic flow of two-phase gas- droplet flows in nozzles." Power engineering: research, equipment, technology 21, no. 3 (November 29, 2019): 86–98. http://dx.doi.org/10.30724/1998-9903-2019-21-3-86-96.

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For practical applications, the description of processes occurring during the flow of two-phase gas-liquid mixtures requires a simple physical and mathematical model that describes the behavior of a two-phase medium in the entire range of phase concentrations changes and in a wide range of pressure changes. Problems of this kind arise in various branches of industry and technology. In the space industry, one often has to deal with the movement of various gases in rocket nozzles, consider the combustion, condensation of various vapors on the nozzle walls and their further impact on the velocity sublayer at the nozzle wall. The large acoustic effect arising from the engines affects the gas-liquid mixture in the nozzles of rocket engines. In the metal industry, metal cooling occurs with the help of nozzles in which the emulsion mixture is supplied under high overpressure. But this is only a short list of applied issues in which one has to deal with a problem of this type. The paper presents the results and directions of study of the problems of two-phase dispersed gas-droplet flows in the nozzles. The main methods of investigation of two- phase heterogeneous flows are described. The main characteristics of heterogeneous two-phase flows in the nozzles, which were confirmed by experimental results, are presented. The calculation of the air-droplet flow in the Laval nozzle is given. The technique, which is based on integral energy equations for two-phase dispersed flows, is described. The main problems and questions concerning the further description and studying of two-component flows are stated.

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Zhao, Dongsheng, Zhijun Wei, Duanyang He, Li Dalin, and Huang Chujiu. "Effect of different particle sizes on combustion characteristics of DCR engines." Journal of Physics: Conference Series 2746, no. 1 (May 1, 2024): 012012. http://dx.doi.org/10.1088/1742-6596/2746/1/012012.

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Abstract The ramjet engine has undergone rapid development in recent decades, and the dual combustion chamber ramjet (DCR) engine was proposed in the last century. Boron, with its high volumetric and gravimetric heating values, is one of the most attractive fuel additives for ramjet engines. However, due to the problem of low combustion efficiency, boron is difficult to achieve high efficiency combustion in practical applications. In order to investigate the combustion characteristics of boron-containing gas solid phase components in DCR engines, the Realizable k-ε model, finite rate/vortex dissipation model and boron particle King model ignition combustion calculation program were written. A three-dimensional full-scale two-phase flow numerical simulation was carried out in the combustion chamber of the DCR engine to calculate the effects of different particle sizes on the combustion characteristics. Through the analysis of the simulation results, the particle size affects the ignition time of boron particles and is positively correlated with the combustion efficiency, but with a non-linear growth. A smaller particle size can promote the ignition of boron particles, improve the solid phase combustion efficiency and achieve efficient combustion.

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Machado, João A. R., Ambria Vasquez, Wing Shun Kwan, Jose M. Fuentes, and Gustavo Menezes. "Implementation of two-phase flow models for recycled materials in embankments." MATEC Web of Conferences 337 (2021): 03002. http://dx.doi.org/10.1051/matecconf/202133703002.

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Recycled materials like Bauxite Residue (Red Mud) and Fly Ash are prevalent in recent feasibility studies on reused materials in geotechnical engineering applications. Red Mud is a mining waste from aluminum manufacturing, and Fly Ash is a by-product of coal combustion in power plants. Nevertheless, to fully reveal the feasibility of using those materials for constructing above-ground earth structures, a better understanding of their unsaturated performance in geo-structure is essential. While some popular empirical models (e.g., van Genuchten 1980) in Soil Water Retention Curves (SWRC) are commonly used to describe soils' unsaturated conditions, those models may not apply to unique materials like Red Mud and Fly Ash. Recently, SWRC curves of both materials were acquired through the Steady-State Centrifuge (SSC) Unsaturated Flow Apparatus (UFA) procedure at Cal State LA. The experimental data were used to develop analytical models following the van Genuchten model. Using a finite-difference software (FLAC) and obtained SWRC curves, this study performed numerical simulations of embankments filled with Fly Ash and Red Mud, comparing it with an embankment filled with typical silty soil with the same dimensions and conditions. Results showed seepage flow rates for Fly Ash and Red Mud are higher when used as fill material as above-ground embankments.

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Andreas Theodorakakos. "Numerical Study of Different Steady-State Flow Rigs for the Tumble Motion Characterization of a Four-Valve Cylinder Head." CFD Letters 15, no. 9 (August 3, 2023): 18–31. http://dx.doi.org/10.37934/cfdl.15.9.1831.

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It is widely accepted that in-cylinder airflow structure strongly affects the performance and combustion of internal combustion (IC) engines. In order to enhance turbulence levels at the time of combustion, modern spark ignition engines (SI) usually employ a tumbling motion inside the cylinder. The tumble generated during the intake phase is mainly controlled by the cylinder head, inlet valves and ports configuration. The use of steady-state flow rigs is a common method to characterize the tumble generating ability of a given configuration. The purpose of this study is to perform CFD numerical simulations of two widely used tumbling measuring steady-state flow rig configurations, in order to compare and correlate the tumble ratios obtained from each one of them. A typical modern four-valve shallow pentroof cylinder head is considered and the flow is simulated for various inlet valve lifts. The results highlight the mass flow rate and tumble ratio differences between the two configurations.

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Smith, Cary, Mark Gragston, Yue Wu, and Zhili Zhang. "Experimental Characterization of Two-Phase Aerated Liquid Ethanol and Jet A Spray Flames." Applied Sciences 10, no. 19 (October 4, 2020): 6950. http://dx.doi.org/10.3390/app10196950.

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This work provides an analysis of an air-assisted atomizing nebulizer’s spray characteristics and combustion behaviors via application of various diagnostics. Two-phase far-field flows and flames of liquid ethanol and practical aviation fuel Jet A were characterized for the droplet distributions, fuel concentrations, and flame dynamics by shadowgraph, Mie scattering, and chemiluminescence imaging of CH*, C2*, and CO2*. Both instantaneous and time-averaged measurements of the two-phase flow and flame characteristics were obtained. Shadowgraphs were used to measure the probability distribution of the droplet diameters. Mie scattering was used to map fuel concentration and obtain the liquid spray cone angles. Estimates of the lifted flame height were obtained by both shadowgraph and Mie scattering, which were verified by the chemiluminescence images. The effect of flow rates on parameters such as flow characteristic, spray cone angle, and drop size spectrum were quantitatively characterized for both ethanol and practical aviation fuel Jet A.

Journal articles on the topic 'Two phase flow combustion'

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