Journal articles: 'Combustion ratio'

1

Cheng, Zhe, Wen Jun Wang, Wen Qing Shen, Ai Wu Fan, and Wei Liu. "Flame Stability of Methane/Air Mixture in a Heat-Recirculating-Type Mesoscale Channel with a Bluff-Body." Applied Mechanics and Materials 325-326 (June 2013): 12–15. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.12.

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To extend the stable combustion range of micro-combustor, a heat-recirculating-type planar micro-combustor fitted with a bluff-body was proposed in the present work. Numerical simulation on CH4/air premixed combustion in this combustor was performed and the stable combustion range was determined, which showed that the blow-off limit increases with the equivalence ratio and the lower flammability limit was extended. Effect of the equivalence ratio and inlet velocity on combustion efficiency and maximum temperature were investigated. The numerical results showed that combustion efficiencies were higher than 99%, and the maximum temperatures were larger than the corresponding adiabatic flame temperature due to the excess enthalpy combustion effect. However, flashback emerged when the inlet velocity was too small and the equivalence ratio is relatively high.

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Cao, H. L., J. N. Zhao, K. Zhang, D. B. Wang, and X. L. Wei. "Diffusion Combustion Characteristics of H₂/Air in the Micro Porous Media Combustor." Advanced Materials Research 455-456 (January 2012): 413–18. http://dx.doi.org/10.4028/www.scientific.net/amr.455-456.413.

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In order to improve thermal to-electric energy conversion efficiency of the micro gas turbine power generation system, a novel micro porous media combustor is designed and experimental investigation on the H2/air diffusion combustion is performed to obtain its combustion characteristics. High efficiency diffusion combustion of H2/air can be stabilized in the very wide operating range, especially at higher excess air ratio. Exhaust gas temperature is markedly improved and meanwhile heat loss ratio is evidently decreased. Moreover, in the certain operating ranges, the greater the combustion thermal power and excess air ratio, the smaller heat loss of the micro combustor will be. The micro porous media combustor should be a preferred micro combustor for developing the micro gas turbine power generation system.

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Wakabayashi, T., S. Ito, S. Koga, M. Ippommatsu, K. Moriya, K. Shimodaira, Y. Kurosawa, and K. Suzuki. "Performance of a Dry Low-NOx Gas Turbine Combustor Designed With a New Fuel Supply Concept." Journal of Engineering for Gas Turbines and Power 124, no. 4 (September 24, 2002): 771–75. http://dx.doi.org/10.1115/1.1473154.

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This paper describes the performance of a dry low-NOx gas turbine combustor designed with a new fuel supply concept. This concept uses automatic fuel distribution achieved by an interaction between the fuel jet and the airflow. At high loads, most of the fuel is supplied to the lean premixed combustion region for low-NOx, while at low loads, it is supplied to the pilot combustion region for stable combustion. A numerical simulation was carried out to estimate the equivalence ratio in the fuel supply unit. Next, through the pressurized combustion experiments on the combustor with this fuel supply unit using natural gas as fuel, it was confirmed that NOx emissions were reduced and stable combustion was achieved over a wide equivalence ratio range.

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Wang, Taiyu, Zhenguo Wang, Zun Cai, Jian Chen, Mingbo Sun, Zeyu Dong, and Bin An. "Effects of combustor geometry on the combustion process of an RBCC combustor in high-speed ejector mode." Modern Physics Letters B 33, no. 27 (September 30, 2019): 1950330. http://dx.doi.org/10.1142/s0217984919503305.

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The combustion characteristics of high-speed ejector mode in a 2-dimensional strut-based RBCC (rocket-based combined cycle) combustor had been investigated numerically in a Mach 2.5 supersonic flow. The numerical approach had been validated by comparing numerical results with available experimental data. Besides, three different hydrogen-air chemical reaction mechanisms had also been compared. The effect of the combustor geometry on the combustion process was then discussed by analyzing the heat release distribution and flow field. It was found that the wall configuration, closeout angle of the converging location and converging ratio all have significant influences on the heat release distribution and flow field structures. It is demonstrated that a converging–diverging wall configuration is beneficial for the combustion process with significant heat release increase compared to the other wall configurations. In addition, the closeout angle of the converging location is also closely related to the combustion performance, and there exists an optimized closeout angle in a specific combustor geometry. It is also revealed that the major heat release region moves upstream obviously with increase in the converging ratio, leading to an enhanced combustion process. However, the converging ratio is still to be optimized to keep a balance between heat release increase and total pressure loss of the supersonic flow.

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Du, Zhibin, Chao Chen, and Lei Wang. "Combustion characteristics of and bench test on “gasoline + alternative fuel”." Thermal Science, no. 00 (2020): 324. http://dx.doi.org/10.2298/tsci200704324d.

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In this study, an evaporative premixed constant-volume combustion system was designed for combustion of liquid fuels, compared with a traditional constant-volume firebomb. The effects of an alternative fuel of gasoline on the combustion characteristics of the laminar flame of gasoline were analyzed, and then a bench test was carried out. The results show that the addition of an alternative fuel of gasoline makes the maximum non-stretched flame propagation velocity of combusting gasoline increasingly close to that of combusting diluted mixed gas. The Markstein lengths of gasoline and ?gasoline + alternative fuel? become shorter with a higher equivalence ratio, and flame combustion becomes increasingly unstable. The laminar combustion velocity of ?gasoline + alternative fuel? rises first and then declines as the equivalence ratio increases. According to the results of the bench test, adding 20% of the alternative fuel into gasoline will exert little impact on the power performance and fuel consumption of the engine, but it will reduce HC emission by 25% and CO emission by 67%.

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Colantonio, R. O. "The Applicability of Jet-Shear-Layer Mixing and Effervescent Atomization for Low-NOx Combustors." Journal of Engineering for Gas Turbines and Power 120, no. 1 (January 1, 1998): 17–23. http://dx.doi.org/10.1115/1.2818073.

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An investigation has been conducted to develop appropriate technologies for a low-NOx, liquid-fueled combustor. The combustor incorporates an effervescent atomizer used to inject fuel into a premixing duct. Only a fraction of the combustion air is used in the premixing process. This fuel-rich mixture is introduced into the remaining combustion air by a rapid jet-shear-layer mixing process involving radial fuel–air jets impinging on axial air jets in the primary combustion zone. Computational modeling was used as a tool to facilitate a parametric analysis appropriate to the design of an optimum low-NOx combustor. A number of combustor configurations were studied to assess the key combustor technologies and to validate the three-dimensional modeling code. The results from the experimental testing and computational analysis indicate a low-NOx potential for the jet-shear-layer combustor. Key features found to affect NOx emissions are the primary combustion zone fuel–air ratio, the number of axial and radial jets, the aspect ratio and radial location of the axial air jets, and the radial jet inlet hole diameter. Each of these key parameters exhibits a low-NOx point from which an optimized combustor was developed. Also demonstrated was the feasibility of utilizing an effervescent atomizer for combustor application. Further developments in the jet-shear-layer mixing scheme and effervescent atomizer design promise even lower NOx with high combustion efficiency.

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Ozturk, Suat. "A Numerical Investigation on Emissions of Partially Premixed Shale Gas Combustion." International Journal of Heat and Technology 38, no. 3 (October 15, 2020): 745–51. http://dx.doi.org/10.18280/ijht.380319.

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The adiabatic, turbulent, and partially premixed combustions of several shale gases and air in a co-axial type combustor are computationally examined under the effects of different equivalence ratios, inlet temperatures, flow rates, humidity ratios, pressure, oxid inlet temperatures and flow rates, and swirl velocities in this study. Shale gases are extracted from Barnette, New Albany, Fayetteville, and Haynesville areas of USA. ANSYS software is used for numerical calculations of combustion. Results show that the maximum NO emissions for Barnette, New Albany, Fayetteville, and Haynesville shale gas occur at the equivalence ratio of 1.42, 1.41, 1.4, and 1.39. The rising fuel inlet temperature increase NO and reduces CO emissions after 300 K. The increasing humidity ratio causes NO and CO mass fractions to decrease. The ascending pressure raises NO up to 4 bar and lowers CO emissions. The increasing oxid flow rate abates the mass fractions of both NO and CO. The rising swirl velocity escalates NO up to 15 m/s and decreases CO emissions for all the shale gas combustions.

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Chein, Reiyu, Yen-Cho Chen, Jui-Yu Chen, and J. N. Chung. "Premixed Methanol–Air Combustion Characteristics in a Mini-scale Catalytic Combustor." International Journal of Chemical Reactor Engineering 14, no. 1 (February 1, 2016): 383–93. http://dx.doi.org/10.1515/ijcre-2014-0061.

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AbstractMethanol catalytic combustion in a mini-scale tubular quartz-made combustor is investigated in this study. An alumina sphere was employed as the support for the platinum catalyst. The experimental results showed that the combustion can be self-ignited at room temperature. Using the combustor wall temperature to characterize the combustor performance, it was found that the combustion temperature can reach a high value within a short time. The experimental results indicated that the combustor performance depends greatly on the fuel/air supply. A higher temperature can be obtained with a higher fuel/air flow rate. The insulated and non-insulated combustor experimental results indicated that heat loss to the environment is an important factor in governing the combustion characteristics due to the large surface/volume ratio. A higher temperature can also be obtained when the combustor is insulated. Because most of the combustion took place at the combustor entrance region, the experimental result suggested that the combustor length can be shortened, leading to a more compact design allowing the combustor integration with various applications. A simple numerical model was built to provide a greater understanding of the combustion characteristics and examine the heat loss effect on combustor performance.

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9

Naeemi, Saeed, and Seyed Abdolmehdi Hashemi. "Numerical investigations on the liftoff velocity of H2-air premixed combustion in a micro-cylindrical combustor with gradually changed section area." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 17 (March 25, 2020): 3497–508. http://dx.doi.org/10.1177/0954406220914925.

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Sustaining and stabilizing flames are crucial issues in micro-combustion. In some micro-electro-mechanical systems such as the micro-thermophotovoltaic system, the flame should be formed in the combustion chamber, not outside it (combustion without liftoff). So, study of the liftoff phenomenon is important and vital in these systems. The aim of this study is to evaluate effect of changing combustor section area on the critical liftoff velocity in a micro-cylindrical combustor. For this purpose, the critical liftoff velocities are numerically identified for four combustor configurations (convergent, divergent, convergent-divergent and divergent-convergent combustion chamber). Premixed mixture of hydrogen-air has been used as reactants for the current investigation. Turbulence model implemented in this paper is RNG k-epsilon and combustion reaction was modeled with 10 species and 21 steps scheme using Eddy Dissipation Concept model. Two non-dimensional numbers d1/d2 (inlet to outlet diameter ratio) and d1/d3 (inlet to throat diameter ratio) are defined. For d1/d2 > 1.0, the combustion chamber is convergent, otherwise it is divergent. When d1/d3 > 1.0, the micro combustor is convergent-divergent and for d1/d3 < 1.0, the micro combustor is divergent-convergent. The results indicate that with increasing d1/d2, the liftoff occurs in a lower inlet flow velocity. With varying d1/d3, from 0.71 (2.0/2.8) to 1.0 (2.0/2.0), the liftoff velocity is reduced. Based on the numerical results, it can be said that the use of convergent and convergent-divergent combustion chamber decreases liftoff velocity. Meanwhile, the combustor with diverging and diverging-converging structure can enhance liftoff velocity. In the same condition, critical liftoff velocity of divergent-convergent micro combustor is the highest among all cases and this configuration is appropriate for Micro Electro-Mechanical Systems that work with high inlet velocity.

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10

Andersson, Ingemar, Mikael Thor, and Tomas McKelvey. "The torque ratio concept for combustion monitoring of internal combustion engines." Control Engineering Practice 20, no. 6 (June 2012): 561–68. http://dx.doi.org/10.1016/j.conengprac.2011.12.007.

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11

Yoon, Myunggon. "Effects of Mean Flow, Temperature Ratio and Area Ratio on Combustion Instability of a Dump Combustor." Combustion Science and Technology 193, no. 3 (September 5, 2019): 453–69. http://dx.doi.org/10.1080/00102202.2019.1661998.

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12

Huang, Mingming, Ruichuan Li, Jikang Xu, Shen Cheng, Haoxin Deng, Zhiyu Rong, Yue Li, and Yanfei Zhang. "Effect of equivalence ratio and staging ratio on the methane MILD combustion in dual-stage combustor." Fuel 307 (January 2022): 121903. http://dx.doi.org/10.1016/j.fuel.2021.121903.

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13

Yuan, Yixiang, Qinghua Zeng, Jun Yao, Yongjun Zhang, Mengmeng Zhao, and Lu Zhao. "Improving Blowout Performance of the Conical Swirler Combustor by Employing Two Parts of Fuel at Low Operating Condition." Energies 14, no. 6 (March 18, 2021): 1681. http://dx.doi.org/10.3390/en14061681.

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Aiming at the problem of the narrow combustion stability boundary, a conical swirler was designed and constructed based on the concept of fuel distribution. The blowout performance was studied at specified low operating conditions by a combination of experimental testing and numerical simulations. Research results indicate that the technique of the fuel distribution can enhance the combustion stability and widen the boundary of flameout within the range of testing conditions. The increase of the fuel distribution ratio improves the combustion stability but leads to an increase in NOx emission simultaneously. The simulation results show the increase of the fuel distribution ratio causes contact ratio increase in the area of lower reference velocity and gas temperature increase. The increased contact ratio and temperature contribute to the blowout performance enhancement, which is identical to the analysis result of the Damkohler number. The reported work in this paper has potential application value for the development of an industrial burner and combustor with high stability and low NOx emission, especially when the combustion system is required to be stable and efficient at low working conditions.

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14

Sivasegaram, S., and J. H. Whitelaw. "Combustion Oscillations in Dump Combustors with a Constricted Exit." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 202, no. 3 (May 1988): 205–10. http://dx.doi.org/10.1243/pime_proc_1988_202_108_02.

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Combustion oscillations in axisymmetric dump combustors have been examined in terms of amplitude and frequency characteristics for two dump-plane area ratios and as a function of combustor length, exit constriction, diameter, flowrate, equivalence ratio and swirl. The flammability limits are similar to those previously determined in disc- and dump-stabilized flames without a constricted exit, but the stability limits are not. Rough combustion, characterized by radiated sound levels more than 12 dB above that in smooth combustion, was observed at equivalence ratios close to the flammability limits for values of swirl number less than 0.2 and was associated with the bulk-mode frequency. With swirl numbers in the range from 0.2 to 0.4, rough combustion was not encountered and, for higher values, existed in a range of equivalence ratios from around 0.8 to 1.4, provided the combustor length and flowrate led to half-wave frequencies less than around 800 Hz. In those ranges of equivalance ratio where the combustion was smooth, discrete frequencies corresponding to the bk-mode and half-wave were observed. The amplitude of the discrete frequency increased when it coincided with the shedding frequency of the shear layer.

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15

Aceves, S. M., J. R. Smith, C. K. Westbrook, and W. J. Pitz. "Compression Ratio Effect on Methane HCCI Combustion." Journal of Engineering for Gas Turbines and Power 121, no. 3 (July 1, 1999): 569–74. http://dx.doi.org/10.1115/1.2818510.

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We have used the HCT (hydrodynamics, chemistry, and transport) chemical kinetics code to simulate HCCI (homogeneous charge compression ignition) combustion of methane-air mixtures. HCT is applied to explore the ignition timing, burn duration, NOx, production, gross indicated efficiency and gross IMEP of a supercharged engine (3 atm. intake pressure) with 14:1, 16:1 and 18:1 compression ratios at 1200 rpm. HCT has been modified to incorporate the effect of heat transfer and to calculate the temperature that results from mixing the recycled exhaust with the fresh mixture. This study uses a single reaction zone that varies as a function of crank angle. The ignition process is controlled by adjusting the intake equivalence ratio and the residual gas trapping (RGT). RGT is internal exhaust gas recirculation, which recycles both thermal energy and combustion product species. Adjustment of equivalence ratio and RGT is accomplished by varying the timing of the exhaust valve closure in either two-stroke or four-stroke engines. Inlet manifold temperature is held constant at 300 K. Results show that, for each compression ratio, there is a range of operational conditions that show promise of achieving the control necessary to vary power output while keeping indicated efficiency above 50 percent and NOx levels below 100 ppm. HCT results are also compared with a set of recent experimental data for natural gas.

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Husain, Arkan Khikhal, Mahmood Attallah Mashkoor, and Fuad Abdul Ameer Khalaf. "Numerical Investigation of Influence of Multi-Line Fuel Injection (Methane) on a Tubular Combustor Emissions of Micro Gas Turbine." Journal of University of Babylon for Engineering Sciences 26, no. 7 (July 5, 2018): 271–85. http://dx.doi.org/10.29196/jubes.v26i7.1537.

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This work presents a technique for design optimization of a gas turbine tubular combustor. This technique is based on the use of computational fluid dynamics (CFD) with CFX solver to reduce emission gases by using multi-line of fuel injection in secondary zone. This research relates the mass fraction of the multi-line of fuel injection as well as the equivalence ratio of the tubular combustion chamber designed for methane fuel. By using k-ε as turbulent model and Probability Density Function (PDF) Flamelet as combustion model. The operating casing data of micro size gas turbine are used, the validation of fuel flow mixing and combustion analyses were carried out with a focus on species concentration in the combustor outlet section. With variant fuel mass flow rate fraction in fuel lines (F2/F1), It was found that, with the new design NO reduced about 56% for the mass fraction 3 in high equivalence ratio and about 30%for the mass fraction 1 for a low equivalence ratio, while reduction in outlet temperature profile (pattern factor) is about 45% → 35%.

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Ruan, S., N. Swaminathan, M. Isono, T. Saitoh, and K. Saitoh. "Simulation of Premixed Combustion with Varying Equivalence Ratio in Gas Turbine Combustor." Journal of Propulsion and Power 31, no. 3 (May 2015): 861–71. http://dx.doi.org/10.2514/1.b35517.

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Yadav, N. P., and Abhijit Kushari. "Vortex combustion in a low aspect ratio dump combustor with tapered exit." Energy Conversion and Management 50, no. 12 (December 2009): 2983–91. http://dx.doi.org/10.1016/j.enconman.2009.07.017.

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19

Sattelmayer, T. "Influence of the Combustor Aerodynamics on Combustion Instabilities From Equivalence Ratio Fluctuations." Journal of Engineering for Gas Turbines and Power 125, no. 1 (December 27, 2002): 11–19. http://dx.doi.org/10.1115/1.1365159.

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Gas turbine combustors are often susceptible to self-excited oscillations, which lead to unacceptable levels of pressure, velocity, and heat release fluctuations. Although instabilities can occur in systems with locally constant equivalence ratio, it is very important to take into account the influence of equivalence ratio fluctuations, which are generated in the fuel air mixer in the unstable case. These fluctuations are convected into the flame and lead to an additional mechanism for the generation of heat release fluctuations. Moreover, entropy waves are produced in the flame, which travel through the combustor and generate additional pressure waves during the acceleration of the flow at the combustor exit. To date, available theories use the physically unrealistic assumption that the equivalence ratio waves as well as the entropy waves are convected downstream without any spatial dispersion due to the combustor aerodynamics. An analytical approach is presented, which allows us to take the spatial dispersion into consideration. For that purpose, the response of the burner and the combustor to an equivalence ratio impulse or an entropy impulse is calculated using the Laplace transformation and a more general transfer function for harmonic waves is derived. The obtained expression has three parameters, which represent the influence of the burner or the combustor aerodynamics, respectively. This equation can be used in numerical codes, which represent the combustion system through a network of acoustic multiports, if the equivalence ratio and the entropy are added to the vector of variables considered. The parameters required for the dynamic combustor model can be deduced from a detailed CFD analysis of the combustor flow in case of the application of the theory to a particular combustor design. As an example, a simple model combustor is used to demonstrate the application of the theory. It is highlighted how the spatial dispersion of the equivalence ratio and entropy fluctuations can be included in the stability analysis. The calculated examples reveal that the influence of both variables on the generation of instabilities is highly overpredicted if the spatial dispersion is not taken into account. Furthermore, it can be deduced from the study that burner and combustor designs with a wide range of convective time scales have advantages with respect to the stability of the combustor.

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20

Gejji, Rohan M., Cheng Huang, Christopher Fugger, Changjin Yoon, and William Anderson. "Parametric investigation of combustion instabilities in a single-element lean direct injection combustor." International Journal of Spray and Combustion Dynamics 11 (July 13, 2018): 175682771878585. http://dx.doi.org/10.1177/1756827718785851.

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Self-excited combustion dynamics in a liquid-fueled lean direct injection combustor at high pressure (1 MPa) are described. Studied variables include combustor and air plenum length, inlet air temperature, equivalence ratio, fuel nozzle location, and fuel composition. Measured pressure oscillations were dependent on combustor geometry and ranged from about 1% of mean chamber pressure at low equivalence ratio, up to 20% at high equivalence ratio. In the most unstable cases, strong pressure modes were measured throughout the frequency spectrum including a band around 1.2–1.5 kHz representing the 4th longitudinal mode, and another band around 7 kHz. The oscillation amplitudes have a non-monotonic dependency on air temperature, and are affected by the placement of the fuel nozzle relative to the throat of the subsonic swirling air flow. The parametric survey provides a rich dataset suitable for validating high-fidelity simulations and their subsequent use in analyzing and interpreting the complex combustion dynamics.

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Wu, X., K. Li, and D. Jiang. "Investigation of air-fuel ratio control using ionic current signal." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 221, no. 9 (September 1, 2007): 1139–46. http://dx.doi.org/10.1243/09544070jauto359.

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The objective of this paper is to investigate the control of air-fuel ratio (AFR) using an ionic current signal. Experimental measurements have been carried out to study the characteristics of the ionic current signal near ignition poles in a constant-volume combustion bomb. The ionic signal is characterized by a front flame and post flame during combustion. The intensity of the ionic signal strongly depends on the AFR at the time of combustion. The maximum values in both the front flame and the post flame will occur at close to the stoichiometric value. Furthermore, minimum values of the durations from ignition to two peaks will also occur where the AFR is close to the stoichiometric value. From this observation of the ion signal characteristics, a feedback control of AFR in a closed loop is proposed and the algorithm is outlined for detecting whether the mixture is in the lean or the rich combustion condition. Then control logic is given based on the information on lean or rich combustion. A unique condition of combustion around stoichiometry is also discussed. It has been shown that the developed control algorithm covers the entire combustion region: lean, rich, and stoichiometric.

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Jackson, M. D., and A. K. Agrawal. "Active Control of Combustion for Optimal Performance." Journal of Engineering for Gas Turbines and Power 121, no. 3 (July 1, 1999): 437–43. http://dx.doi.org/10.1115/1.2818492.

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Combustion-zone stoichiometry and fuel-air premixing were actively controlled to optimize the combustor performance over a range of operating conditions. The objective was to maximize the combustion temperature, while maintaining NOx within a specified limit. The combustion system consisted of a premixer located coaxially near the inlet of a water-cooled shroud. The equivalence ratio was controlled by a variable-speed suction fan located downstream. The split between the premixing air and diffusion air was governed by the distance between the premixer and shroud. The combustor performance was characterized by a cost function evaluated from time-averaged measurements of NOx and oxygen concentrations in products. The cost function was minimized by the downhill simplex algorithm employing closed-loop feedback. Experiments were conducted at different fuel flow rates to demonstrate that the controller optimized the performance without prior knowledge of the combustor behavior.

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Liang, Geng, Yan Bai, Guotian Yang, and Wen Li. "A Boiler Combustion Control System with Combustion Ratio Optimisation and Soft Measurements." Measurement and Control 43, no. 4 (May 2010): 112–15. http://dx.doi.org/10.1177/002029401004300403.

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Hasini, Hasril, Norshah Hafeez Shuaib, and Wan Ahmad Fahmi Wan Abdullah. "CFD Analysis of Temperature Distribution in Can-Type Combustor Firing Synthetic Gas." Applied Mechanics and Materials 393 (September 2013): 741–46. http://dx.doi.org/10.4028/www.scientific.net/amm.393.741.

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This paper presents CFD analysis of the effect of syngas combustion in a full scale gas turbine combustor with specific emphasis given to the flame and flue gas temperature distribution. A base case solution was first established using conventional natural gas combustion. Actual operating boundary conditions such as swirl, diffusion and fuel mass flow were imposed on the model. The simulation result is validated with the flame temperature of typical natural gas combustion. Result from flow and combustion calculation shows reasonable trend of the swirl mixing effect. The maximum flame temperature was found to be the highest for syngas with the highest H2/CO ratio. However, the flue gas temperature was found to be approximately identical for all cases. The prediction of temperature distribution in the combustor would enable further estimation of pollutant species such as CO2and NOxin complex regions within the combustor.

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Hosseini, Seyed, Evan Owens, John Krohn, and James Leylek. "Experimental Investigation into the Effects of Thermal Recuperation on the Combustion Characteristics of a Non-Premixed Meso-Scale Vortex Combustor." Energies 11, no. 12 (December 4, 2018): 3390. http://dx.doi.org/10.3390/en11123390.

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In small-scale combustors, the ratio of area to the combustor volume increases and hence heat loss from the combustor’s wall is significantly enhanced and flame quenching occurs. To solve this problem, non-premixed vortex flow is employed to stabilize flames in a meso-scale combustion chamber to generate small-scale power or thrust for propulsion systems. In this experimental investigation, the effects of thermal recuperation on the characteristics of asymmetric non-premixed vortex combustion are studied. The exhaust gases temperature, emissions and the combustor wall temperature are measured to evaluate thermal and emitter efficiencies. The results illustrate that in both combustors (with/without thermal recuperator), by increasing the combustion air mass flowrate, the wall temperature increases while the wall temperature of combustor with thermal recuperator is higher. The emitter efficiency calculated based on the combustor wall temperature is significantly increased by using thermal recuperator. Thermal efficiency of the combustion system increases up to 10% when thermal recuperator is employed especially in moderate Reynolds numbers (combustion air flow rate is 120 mg/s).

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Hwang, D., Y. Song, and K. Ahn. "Combustion instability characteristics in a dump combustor using different hydrocarbon fuels." Aeronautical Journal 123, no. 1263 (April 30, 2019): 586–99. http://dx.doi.org/10.1017/aer.2019.19.

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ABSTRACTThe combustion instability characteristics in a model dump combustor with an exhaust nozzle were experimentally investigated. The first objective was to understand the effects of operating conditions and geometric conditions on combustion instability. The second objective was to examine more generalised parameters that affect the onset of combustion instability. Three different premixed gases consisting of air and hydrocarbon fuels (C2H4, C2H6, C3H8) were burnt in the dump combustor at various inlet velocity, equivalence ratio and combustion chamber length. Dynamic pressure transducer and photomultiplier tube with a bandpass filter were used to measure pressure fluctuation and CH* chemiluminescence data. Peak frequencies and their maximum power spectral densities of pressure fluctuations at same equivalence ratios showed different trends for each fuel. However, the dynamic combustion characteristics of pressure fluctuations displayed consistent results under similar characteristics chemistry times regardless of the used hydrocarbon fuels. The results showed that characteristic chemistry time and characteristic convection time influenced combustion instabilities. It was found that the convective-acoustic combustion instability could be prevented by increasing the characteristic chemistry time and characteristic convection time.

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Li, Weixuan, Xiong Chen, Wenxiang Cai, and Omer Musa. "Numerical Investigation of the Effect of Sudden Expansion Ratio of Solid Fuel Ramjet Combustor with Swirling Turbulent Reacting Flow." Energies 12, no. 9 (May 10, 2019): 1784. http://dx.doi.org/10.3390/en12091784.

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In this paper, the effect of sudden expansion ratio of solid fuel ramjet (SFRJ) combustor is numerically investigated with swirl flow. A computational fluid dynamics (CFD) code is written in FORTRAN to simulate the combustion and flow patterns in the combustion chamber. The connected-pipe facility is used to perform the experiment with swirl, and high-density Polyethylene (HDPE) is used as the solid fuel. The investigation is performed with different sudden expansion ratios, in which the port and inlet diameters are independently varied. The results indicated that the self-sustained combustion of the SFRJ occurs around the reattachment point at first, and then the heat released in reattachment point is used to achieve the self-sustained combustion in the redevelopment zone. The average regression rate is proportional to the sudden expansion ratio for the cases with a fixed port diameter, which is mainly dominated by the enhancement of heat transfer in backward-facing step. However, the average regression rate is inversely proportional to the sudden expansion ratio for the cases with fixed inlet diameter, which is influenced by the heat transfer mechanism of developed turbulent flow in the redevelopment zone.

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Li, Fan, Mingbo Sun, Zun Cai, Yong Chen, Yongchao Sun, Fei Li, and Jiajian Zhu. "Effects of Additional Cavity Floor Injection on the Ignition and Combustion Processes in a Mach 2 Supersonic Flow." Energies 13, no. 18 (September 14, 2020): 4801. http://dx.doi.org/10.3390/en13184801.

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Effects of additional cavity floor injection on the ethylene ignition and combustion processes in a cavity-based scramjet combustor are investigated experimentally in a Mach 2.0 supersonic flow using flame luminosity and CH* (CH radical) spontaneous emission methods and static pressure measurements. Numerical calculation is performed to study the non-reacting flow-field structures prior to ignition. Two injection schemes, including the cavity upstream injection scheme and the combined injection scheme with an additional cavity floor injection, are compared to study the effects of the additional cavity floor injection on the ignition and combustion processes. It is found that there exists an equivalence ratio upper limit for maintaining stable combustion for the cavity upstream injection scheme. As the equivalence ratio further increases, the fuel jet penetration is improved accordingly, and thus, the interaction between the fuel jet and the cavity is weakened, which can lead to the ignition failure and flame blowout during combustion. On the contrary, although the combined injection scheme has a minor effect on combustion enhancement at the same global equivalence ratio, it can also provide a more favorable flow-field environment that enables more successful ignitions and better flame stabilizations. For the combined injection scheme, as the equivalence ratio increases, the initial flame propagations are observed to perform different routines during the ignition process, and the major combustion reaction zone tends to move further downstream the cavity shear layer. It is concluded that the advantages of the combined injection scheme with an additional cavity floor injection are more significant when the equivalence ratio is higher, as well as that the interaction between the fuel jet and the cavity becomes weaker.

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Zhang, Xiao You, Yong Jun Wu, and Li You Xu. "Influence of Change of H/O Mixture Ratio on Combustion in the Combustor of the Micro Thermophotovoltaic System." Advanced Materials Research 156-157 (October 2010): 408–12. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.408.

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The change of H/O mixture ratio has affect on the combustion of H/O mixed gas in the micro combustor, and the temperature distribution of the micro combustor wall are researched in this paper, when the mixed gas flux is different in the combustor of the micro thermophotovoltaic system. The result of the test indicates that H/O mixed gas can combust stably in the micro combustor. As mixed gas flux is 3.92g/h and H/O mixture ratio is 2, the temperature of the micro combustor wall is about to 1100K, which matches work requirement of the micro thermophotovoltaic system.

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Mirmohammadsadeghi, Mahmoudreza, Hua Zhao, and Akira Ito. "Optical study of gasoline substitution ratio and diesel injection strategy effects on dual-fuel combustion." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 4 (July 16, 2019): 1075–97. http://dx.doi.org/10.1177/0954407019864013.

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Ever growing population and increased vehicles have resulted in higher atmospheric concentration of the greenhouse gases, such as carbon dioxide and methane, thus increasing our planet’s average temperature leading to irreversible climate changes, which has led to increasingly demanding and stricter legislations on pollutant emission and CO2, as well as fuel economy targets for the automotive industry. As a result, a great deal of efforts and resources has been spent on the research and development of high efficiency and low emission engines for automotive applications in the attempt to reduce greenhouse gas emissions and levels of nitrogen oxides and soot emissions, which affect the air quality. This research has developed strategies to investigate the combustion characteristics, engine performance and exhaust emission of diesel–gasoline dual-fuel operation in a Ricardo Hydra single-cylinder optical engine running at 1200 r/min, equipped with a high-pressure common rail injection system for diesel fuel delivery, and a port fuel injection system, designed and manufactured by the author, for gasoline fuel delivery, in order to allow for dual-fuel operations. In-cylinder pressure measurement is used for calculating all engine parameters, heat release rate and efficiency. In addition to the thermodynamic analysis of the combustion parameters, high-speed imaging of spray and combustion chemiluminescence was used for the optical analysis of the effect of the above-mentioned parameters on auto-ignition and combustion processes. Effects of different substitution ratios and diesel injection strategies at low engine loads were studied when the total fuel energy was kept constant. The three main substitution ratios used in this study include 45%, 60% and 75%, which also indicates the amount of fuel energy from port-injected gasoline, where the rest is provided by the direct injection of diesel. Depending on the testing conditions, such as injection strategy and intake conditions, some dual-fuel operations were able to deliver high efficiency and improved emissions compared to that of a pure diesel engine operation, with the diesel–gasoline operation offering more consistency in improved thermal efficiency. The optical analysis of the combustion illustrates the main difference in the flame propagation, distribution and quality for each substitution percentage, as well as the condition under examination. It was observed that combustions with higher concentration of diesel fuel having more diffusion-like combustion, especially with diesel injection timings closer to the top dead centre, where there is less time for the two fuel and air to properly mix before combustion occurs, resulted in higher temperature and levels of NOx due to the pockets of high diesel concentrations within the combustion chamber, whereas higher concentration of gasoline, especially at earlier diesel injection timings, resulted in more homogeneous fuel mixture and thus lower combustion temperatures. In other words, when the gasoline substitution ratio is lower, optimised start of injection is advanced further, so that richer diesel mixture needs longer ignition delay to have proper combustion timing, and combustion is milder and peak heat release rate is slightly lower due to less local diesel rich mixture area by means of earlier injection timing, and in terms of emissions, lower gasoline substitution ratio, decreases NOx with more homogeneous diesel mixture, and same can be said for total hydrocarbon. Performing the thermodynamics testing with an all metal piston alongside the optical testing allowed for the confirmation of these outcomes. This study not only delivers an insight to the benefits of dual-fuel engine operation, it also represents the benefits of optical engines in providing better understanding of engine operation and ways of improving it.

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Cai, Chaozhi, Leyao Fan, and Bingsheng Wu. "Numerical simulation of combustor temperature performance of a high-temperature high-speed heat-airflow simulation system." World Journal of Engineering 13, no. 5 (October 3, 2016): 422–31. http://dx.doi.org/10.1108/wje-08-2016-0049.

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Purpose This paper aims to understand the outlet temperature distribution of the combustor of a high-temperature, high-speed heat-airflow simulation system. Design/methodology/approach The paper uses numerical simulation to study the temperature distribution of the combustor of a high-temperature, high-speed heat-airflow simulation system. First, the geometrical model of the combustor and the combustion model of the fuel are established. Then, the combustion of fuel in the combustor is simulated by using FLUENT under various conditions. Finally, the results are obtained. Findings The paper found three conclusions: when the actual fuel–gas ratio is equal to the theoretical fuel–gas ratio, the temperature in the combustor of the high-temperature, high-speed heat-airflow simulation system (HTSAS) can reach its highest and the distribution is the most uniform. Although increases in the total temperature of the inlet air can increase the highest temperature in the combustor of the HTSAS, the average temperature of the combustor outlet will decrease. At the same time, it will lead to an uneven temperature distribution of the combustor outlet. When the spray angle of the kerosene droplet is at 30 degrees, the outlet temperature field of the combustor is more uniform. Originality/value The paper presents a method to analyze the combustion performance of fuel and the gas temperature distribution in the combustor. The results will lay the foundation for the gas temperature control of a combustor.

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Suzuki, Y., T. Satoh, M. Kawano, N. Akikawa, and Y. Matsuda. "Combustion Test Results of an Uncooled Combustor With Ceramic Matrix Composite Liner." Journal of Engineering for Gas Turbines and Power 125, no. 1 (December 27, 2002): 28–33. http://dx.doi.org/10.1115/1.1501916.

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A reverse-flow annular combustor with its casing diameter of 400 mm was developed using an uncooled liner made of a three-dimensional woven ceramic matrix composite. The combustor was tested using the TRDI high-pressure combustor test facility at the combustor maximum inlet and exit temperature of 723 K and 1623 K, respectively. Although both the material and combustion characteristics were evaluated in the test, this report focused on the combustion performance. As the results of the test, the high combustion efficiency and high heat release ratio of 99.9% and 1032 W/m3/Pa were obtained at the design point. The latter figure is approximately twice as high as that of existing reverse-flow annular combustors. Pattern factor was sufficiently low and was less than 0.1. Surface temperatures of the liner wall were confirmed to be higher than the limit of the combustor made of existing heat-resistant metallic materials.

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Gao, Tianyun, Jianhan Liang, Mingbo Sun, and Zhan Zhong. "Dynamic combustion characteristics in a rectangular supersonic combustor with single-side expansion." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 10 (August 3, 2016): 1862–72. http://dx.doi.org/10.1177/0954410016662062.

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Dynamic combustion characteristics of a rectangular scramjet combustor with single-side expansion were studied experimentally and numerically. Experiments were implemented with an isolator entrance Mach number of 3.46, and an air stagnation temperature of 1430 K. Ethylene was utilized to fuel the combustor over an equivalence ratio range of 0.20 < φ < 0.63. Results indicated that the combustion modes varied from different equivalence ratios. For an intermediate φ = 0.375, an intermittent dynamic combustion occurred. During the dynamic process, the flame sometimes stabilized in the jet wake of the top cavity, and at other time it oscillated between dual parallel cavities. The pseudo-shock train traveled periodically along the length of the combustor, and the penetration depths of the two injectors exchanged. Quantitative analysis illustrated that the average frequency of unsteady combustion was approximately 200 Hz. The reason for the occurrence of the self-sustained dynamic process was related to the interactions between the shock-induced separated region and heat release.

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Raison, R. J., P. K. Khanna, and P. V. Woods. "Mechanisms of element transfer to the atmosphere during vegetation fires." Canadian Journal of Forest Research 15, no. 1 (February 1, 1985): 132–40. http://dx.doi.org/10.1139/x85-022.

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Published data and newly presented evidence demonstrate that the proportion of N or P lost from plant material during combustion under a wide range of conditions increases linearly with percentage loss of fuel weight during combustion. For N the correlation is strong, and the slope (β) of the regression line approaches unity for combustions under field or simulated-field conditions, but reduces to 0.78 for materials combusted in a muffle furnace. Almost all of the losses of N are due to volatilization. The relationship for P is less well defined, and β is lower (0.56 for field studies; about 0.2 for simulated-field or laboratory combustions). Calcium is not volatilized at the temperatures generated in most vegetation fires, thus increases in the ratio of Ca to other elements during combustion (i.e., higher ratios in burnt residue) indicate nonparticulate transfer of elements to the atmosphere. Increased ratios for Ca to N, P, K, Mg, Mn, and B were demonstrated for several components of eucalypt litter fuels, especially where the degree of combustion was high. The positive relationship between increase in Ca:element ratio and percentage element loss in nonparticulate form during combustion, is of Mitscherlich form so that initial increases in the ratio represent proportionally most element loss. Partitioning of the transfer of elements from the litter and understory to the atmosphere measured during low-intensity fires in three eucalypt forest communities demonstrated a low particulate contribution (and thus a high nonparticulate transfer) for N, K, P, and B. Particulate contributions to elemental transfers are less where combustion is more complete, resulting in formation and transport of fine grey ash which has a high Ca:element ratio. Of particular ecological importance is the significant transfer of P by nonparticulate mechanisms, because such P is likely to be permanently lost from burnt sites and natural rates of P replacement are usually very slow. Fine grey or white ash is highly nutrient enriched (e.g., up to 50-fold for P compared with concentrations in unburnt fuel), and hence its transport from the site in the smoke column, or subsequently by either wind or water, can result in substantial export of nutrients.

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SINGH, Prabhat, Dharmahinder Singh CHAND, Sourav PAL, and Aadya MISHRA. "Influence of Alternative Fuel Ratio on Turbocharger Combustor." INCAS BULLETIN 11, no. 4 (December 8, 2019): 179–89. http://dx.doi.org/10.13111/2066-8201.2019.11.4.16.

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The present study investigates the effects of alternative fuel properties on combustion performance, in order to ensure reliable combustion performance using various fuel blends for powering an engine. The increasing rate of fuel cost and depletion of fossil fuels has led to the search for alternate fuels. Palm biodiesel derived from palm fatty acids meets the fuel requirements of an aircraft and is compatible with any engine without modifications. Viability of using a blend of present fossil fuels with biodiesel is studied. The engine was operated with petrol, diesel, palm biodiesel and a blend of these three fuels as a pair, with various ratios. The fuel was injected into the combustion chamber at an angle of 45o to the airflow and ignited using a spark plug. The blended fuel is found to have better efficiency than petrol or diesel. Furthermore, the low cost and abundant availability of the biofuel make it a viable alternative to the petroleum-based fuels currently in use. The combustion time and ignition delay are decreased with efficient biofuel due to high oxygen content and high octane number of the biofuel.

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Yang, Shuang Ping, Jie Dong, and Miao Wang. "Experiment on Combustion-Supporting Agent on PCI for Combustibility of Coal Powder." Materials Science Forum 658 (July 2010): 248–51. http://dx.doi.org/10.4028/www.scientific.net/msf.658.248.

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In order to improve the combustion effects of pulverized coal and replacement ratio of coals, the combustion- supporting mechanism, development and applications are analyzed and industry experiment are carried out based on the research of combustion- supporting agent without alkalis on coals combustion with TG- DTG- DSC ways. The results show that there is an optimum addition percent for coals combustion with combustion- supporting agent. The coal ratio and coke ratio are improved obviously with 1.7%combustion- supporting agent in LongGang.

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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.

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Arora, Nidhi, and Swati Mehta. "Air fuel ratio detector corrector for combustion engines using adaptive neuro-fuzzy networks." An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 3, no. 2 (May 29, 2013): 85–97. http://dx.doi.org/10.11121/ijocta.01.2013.00152.

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A perfect mix of the air and fuel in internal combustion engines is desirable for proper combustion of fuel with air. The vehicles running on road emit harmful gases due to improper combustion. This problem is severe in heavy vehicles like locomotive engines. To overcome this problem, generally an operator opens or closes the valve of fuel injection pump of locomotive engines to control amount of air going inside the combustion chamber, which requires constant monitoring. A model is proposed in this paper to alleviate combustion process. The method involves recording the time-varying flow of fuel components in combustion chamber. A Fuzzy Neural Network is trained for around 40 fuels to ascertain the required amount of air to form a standard mix to produce non-harmful gases and about 12 fuels are used for testing the network’s performance. The network then adaptively determines the additional/subtractive amount of air required for proper combustion. Mean square error calculation ensures the effectiveness of the network’s performance.

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Hussain, Dr Mohammad N., and Rusul M. Khazaal. "Effects of Fuel - Air Ratio on the Flame Propagation for S.I. Engines." Journal of Petroleum Research and Studies 2, no. 1 (May 5, 2021): 117–24. http://dx.doi.org/10.52716/jprs.v2i1.39.

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As a result of the rapid development in the various transport means, a great concern was shown in the design and development of spark-ignition engines to achieve the best efficiency and performance and to guarantee a full combustion of the fuel inside the combustion chamber to avail all the energy of the fuel entering the cylinder. This work involves the study of the reaction equations of the combustion for stochiometric and rich cases, and the study of combustion products and their effects on the environment.

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Debnath, Pinku, and Krishna Murari Pandey. "Effect of Blockage Ratio on Detonation Flame Acceleration in Pulse Detonation Combustor Using CFD." Applied Mechanics and Materials 656 (October 2014): 64–71. http://dx.doi.org/10.4028/www.scientific.net/amm.656.64.

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Detonation is the supersonic mode of combustion process which is essential for energy release from combustion process. Detonation is the more energetic process compare to deflagration mode of combustion process. The turbulence combustion flame cannot transit itself into detonation combustion process. So objective of this paper is to investigate the effect of obstacles configuration landed in detonation tube channel to propagate the detonation wave and diffraction encounters in an obstacles site. Four different cases of obstacles blockage ratio (BR) 0.4, 0.5, 0.6 and 0.7 were studied for detonation flame acceleration in detonation tube. A three dimensional computational simulation was done using unsteady green-gauss cell based solver for adopting the combustion simulation. As a result detonation flame propagation, detonation flame velocity and detonation flame pressure were increase in reducing blockage ratio from 0.7 to 0.4 and eddy viscosity of combustible mixture was increase with increasing the blockage ratio. From the analyzed four blockage ratio BR=0.4 is suitable for detonation mode of combustion and flame acceleration.

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41

Lieuwen, T., H. Torres, C. Johnson, and B. T. Zinn. "A Mechanism of Combustion Instability in Lean Premixed Gas Turbine Combustors." Journal of Engineering for Gas Turbines and Power 123, no. 1 (April 2, 2000): 182–89. http://dx.doi.org/10.1115/1.1339002.

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There has been increased demand in recent years for gas turbines that operate in a lean, premixed (LP) mode of combustion in an effort to meet stringent emissions goals. Unfortunately, detrimental combustion instabilities are often excited within the combustor when it operates under lean conditions, degrading performance and reducing combustor life. To eliminate the onset of these instabilities and develop effective approaches for their control, the mechanisms responsible for their occurrence must be understood. This paper describes the results of an investigation of the mechanisms responsible for these instabilities. These studies found that combustors operating in a LP mode of combustion are highly sensitive to variations in the equivalence ratio (ϕ) of the mixture that enters the combustor. Furthermore, it was found that such ϕ variations can be induced by interactions of the pressure and flow oscillations with the reactant supply rates. The ϕ perturbations formed in the inlet duct (near the fuel injector) are convected by the mean flow to the combustor where they produce large amplitude heat release oscillations that drive combustor pressure oscillations. It is shown that the dominant characteristic time associated with this mechanism is the convective time from the point of formation of the reactive mixture at the fuel injector to the point where it is consumed at the flame. Instabilities occur when the ratio of this convective time and the period of the oscillations equals a specific constant, whose magnitude depends upon the combustor design. Significantly, these predictions are in good agreement with available experimental data, strongly suggesting that the proposed mechanism properly accounts for the essential physics of the problem. The predictions of this study also indicate, however, that simple design changes (i.e., passive control approaches) may not, in general, provide a viable means for controlling these instabilities, due to the multiple number of modes that may be excited by the combustion process.

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Lee, Y. W., and T. L. Jiang. "Effects of Fuel Impingement-Cooling on the Combustion Flow in a Small Bipropellant Liquid Rocket Thruster." Journal of Mechanics 31, no. 2 (January 23, 2015): 161–70. http://dx.doi.org/10.1017/jmech.2014.81.

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ABSTRACTIn the present study, a three-dimensional computer code, based on the computer software KIVA-3, was developed for the combustion-flow simulation of a bipropellant liquid rocket thruster. A jets-impingement model is proposed for the unlike-doublet jet impingement issue. The computer code is employed to simulate a small bipropellant liquid rocket engine installed with three unlike-doublet injectors of NTO and MMH as well as six fuel injectors injecting MMH toward the combustor wall for cooling. Effects of the fuel-injection cooling on the combustion flow, combustion efficiency, and wall temperature were investigated. The results obtained from the present study show that under the present injector configuration and a constant total fuel-flow rate, higher cooling-fuel ratios make the atomized mixing flow of NTO and MMH shift toward the combustor wall, resulting in lower combustion efficiency and chamber pressure; however, low cooling-fuel ratios are unable to keep the wall-temperature sufficiently low. To overcome this issue, the proposed three-dimensional computer code calculates/locates the optimal cooling-fuel ratio that bears high combustion efficiency for a bipropellant liquid rocket combustor while keeping the chamber wall sufficiently cool.

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Jin, Xuan, Chibing Shen, Rui Zhou, and Xinxin Fang. "Effects of LOX Particle Diameter on Combustion Characteristics of a Gas-Liquid Pintle Rocket Engine." International Journal of Aerospace Engineering 2020 (September 15, 2020): 1–16. http://dx.doi.org/10.1155/2020/8867199.

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LOX/GCH4 pintle injector is suitable for variable-thrust liquid rocket engines. In order to provide a reference for the later design and experiments, three-dimensional numerical simulations with the Euler-Lagrange method were performed to study the effect of the initial particle diameter on the combustion characteristics of a LOX/GCH4 pintle rocket engine. Numerical results show that, as the momentum ratio between the radial LOX jet and the axial gas jet is 0.033, the angle between the LOX particle trace and the combustor axial is very small. Due to the large recirculation zones, premixed combustion mainly occurs in the injector wake region. As the initial LOX particle diameter increases, the LOX evaporation rate and the combustion efficiency decrease until the combustion terminates with the initial LOX particle diameter greater than 110 μm. The oscillation amplitude of the combustor pressure increases significantly along with the increase of the initial LOX particle diameter, and the low-frequency unstable combustion occurs when the initial LOX particle diameter exceeds 60 μm. The combustor pressure oscillation at about 40 Hz couples with the swinging process of spray and flame, while the unsteady LOX evaporation amplifies the combustor pressure oscillations at 80 Hz and its harmonic frequency.

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Park, Sang-Woo, Jae-Kyung Yang, and Kyung-Ryul Baek. "Fuel Ratio and Combustion Characteristics of Torrefied Biomass." Journal of Korea Society of Waste Management 30, no. 4 (June 30, 2013): 376–82. http://dx.doi.org/10.9786/kswm.2013.30.4.376.

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Kirtas, M., M. Disseau, D. Scarborough, J. Jagoda, and S. Menon. "Combustion dynamics in a high aspect ratio engine." Proceedings of the Combustion Institute 29, no. 1 (January 2002): 917–23. http://dx.doi.org/10.1016/s1540-7489(02)80116-x.

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Sacks, Gavin L., Ying Zhang, and J. Thomas Brenna. "Fast Gas Chromatography Combustion Isotope Ratio Mass Spectrometry." Analytical Chemistry 79, no. 16 (August 2007): 6348–58. http://dx.doi.org/10.1021/ac0706325.

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Jia, Shuan-zhu, Shi-guo Du, Jian-wei Zhen, and Xin-hui Yang. "The Combustion Performance and Ingredient Ratio of Thermite." IOP Conference Series: Earth and Environmental Science 104 (December 2017): 012001. http://dx.doi.org/10.1088/1755-1315/104/1/012001.

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Zhu, Jianjun, Peng Li, and Xin Geng. "Combustion characteristics of different premixed methanol charge compression ignition combustion modes." Thermal Science 24, no. 3 Part A (2020): 1609–15. http://dx.doi.org/10.2298/tsci190512028z.

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This paper proposes two dual fuel combustion modes for a Diesel engine based on two alternative fuels and explores the influence of engine compression ratio on combustion and fuel economy characteristics under heavy loads. The results show that reducing the compression ratio can reduce the pressure rise rate of the combustion mode of methanol premixed charge induced ignition, owing to a decrease in the brake thermal efficiency.

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Li, Gong Fa, Yuan He, Guo Zhang Jiang, Jian Yi Kong, and Liang Xi Xie. "Research on the Air-Fuel Ratio Intelligent Control Method for Coke Oven Combustion Energy Saving." Applied Mechanics and Materials 121-126 (October 2011): 2873–77. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.2873.

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Coke combustion process, the constant proportion of the combustion air-fuel ratio control results in low combustion efficiency and fault-prone, difficult to adapt to changes in complex working conditions. Application of intelligent technology of case-based reasoning, fuzzy control, proposed for intelligent energy saving air-fuel ratio control method. Based on current trends in working conditions and combustion process in case of failure, predict the typical faults with case-based reasoning technology to the combustion process. On this basis, through case-based reasoning algorithm realize the real-time air-fuel ratio correction. Based on fuzzy-PID temperature cascade control we can obtain the appropriate flue gas flow and flue suction and realize the stability of the combustion process to achieve optimal control.

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Chen, Peng, Wansheng Nie, Kangkang Guo, Xing Sun, Yu Liu, and Haiqing Wang. "The Effects of Non-uniform Distribution of Oxidizer Flow on High-Frequency Combustion Instability." MATEC Web of Conferences 257 (2019): 01005. http://dx.doi.org/10.1051/matecconf/201925701005.

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The numerical calculation of three-dimensional unsteady combustion for the combustion chamber of LOX/kerosene high pressure staged combustion rocket engine was carried out. By changing the offset ratio of oxygen mass flow rate in the edge area of the injector face, computational studies were conducted to investigate the effects of non-uniform distribution of oxidizer flow on combustion instability for a liquid-propellant rocket engine. The calculation results show that the offset ratio of oxygen mass flow rate changes the distribution of heat release in the combustion chamber. Within a certain range of offset ratio, the non-uniform distribution degree of oxidizer flow enhances the coupling between the pressure and heat release. As a result, it leads to an increase in the pressure oscillation amplitude in the combustion chamber. However, if the offset ratio is too large, the oxygen-fuel ratio will be too small in some regions, which will reduce coupling between the pressure and heat release and increase the damping of combustion instability.

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Journal articles on the topic 'Combustion ratio'

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