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Computational Analysis of Shrouded Ejector Effect on Starting Vortex and Combustion Efficiency in pulse detonation combustor with Different Fuels

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COMBUSTION SCIENCE AND TECHNOLOGY 2025年第5期197卷 976-998页

作者： Debnath, Pinku Pandey, Krishna Murari Natl Inst Technol Agartala Tripura Mech Engn Dept Agartala India Natl Inst Technol Silchar Mech Engn Dept Silchar Assam India Natl Inst Technol Agartala Tripura Mech Engn Dept Agartala 799046 India

This research paper deals with the starting vortex of detonation combustion wave flow field in pulse detonation combustor (PDC). In order to achieve the potential pressure gain from PDC the shrouded ejectors are placed at exit section of detonation tube. Therefore, influence of shrouded ejector position plays a great role on leading vortex and reduction of NOx formation. Furthermore, n-butane (C4H10) and hydrogen (H2) fuel are used for stoichiometric ($\phi $phi= 1) fuel-air mixture condition to simulate the thermal and prompt NOx formation at pulse time of 0.022s to 0.030s. The LES turbulence model is used to simulate the unsteady flow field in CFD based fluent platform. The one step irreversible chemical kinetics model analyzed the details of exothermic chemical reaction mechanism inside the combustor. The non-dimensional value of $\delta $delta/d = 1.5 geometry position of shrouded ejector is better for leading vortex. So far, pickup detonation wave speed of 2306 ms-1 is obtained at shortest pulse time of 0.028s and this magnitude is higher than C-J velocity. The minimum pollutant number of 0.0000341 is obtained from hydrogen-air detonation, this magnitude is lesser compared to n-butane (C4H10)-air combustion. Furthermore, the maximum combustion efficiency of 85% is obtained from hydrogen-air mixture in detonation combustion process, which is comparatively higher than deflagration combustion process.

关键词： Shrouded ejector vortex computational fluid dynamics pulse detonation combustor detonation

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Influence of high-pressure intermittent fuel supply mode on operation characteristics of pulse detonation combustor

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APPLIED THERMAL ENGINEERING 2024年 246卷

作者： Wang, Dingding Zheng, Longxi Lu, Jie Tan, Wenhao Li, Qing Northwestern Polytech Univ Sch Power & Energy Xian 710129 Shaanxi Peoples R China

In order to reduce the atomization particle size in a liquid fueled pulse detonation combustor (PDC), a highpressure intermittent fuel supply system was designed and tested with a U-shaped PDC (U-PDC). Influence of high-pressure intermittent fuel supply mode on the initiation characteristics of the U-PDC was experimentally investigated. Gasoline\air was used as fuel and oxidant in the test, the atomization particle size of high-pressure direct injector was obtained and the detonation characteristics of U-PDC were analyzed. The results show that the particle size of a single direct spray is 10 mu m to 30 mu m, and the atomization particle size of the three direct injector combination is about 20 mu m to 55 mu m under simulated operating conditions. Smaller atomization particle size is conducive to fuel evaporation and participation in combustion The high-pressure intermittent fuel supply mode can realize stable operating with the U-PDC from 10 Hz -30 Hz, and reduce the influence of the periodic pressure pulsation in the detonation chamber on the fuel supply stability. The detonation wave velocity increases with the increased frequency, and the DDT distance is shortened from 733 mm to 616 mm. This laid the foundation for subsequent high-pressure intermittent fuel supply technology in PDC.

关键词： High-pressure fuel supply pulse detonation combustor DDT Fuel atomization Intermittent fuel supply mode

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Numerical and experimental investigation on the operating characteristics of fan-shaped pulse detonation combustor

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AEROSPACE SCIENCE AND TECHNOLOGY 2024年 155卷

作者： Peng, Chenxu Zheng, Longxi Lu, Jie Luo, Zhenkun Zhang, Jiabo Huang, Kang Northwestern Polytech Univ Sch Power & Energy Xian 710129 Peoples R China China Aerodynam Res & Dev Ctr Mianyang 621000 Peoples R China

The internal flow channel of a turbine engine is typically annular. When circular pulse detonation combustors (PDCs) are installed in this channel, there is a problem with low section utilization rates. To solve this problem, a single-tube fan-shaped PDC test system was developed. The effects of ignition distance on the operating characteristics of the fan-shaped PDC using air and gasoline under different frequencies were studied through both experiment and 3-D numerical simulation. Numerical simulation was also used to investigate the formation and propagation characteristics of detonation waves. The results show that the fan-shaped PDC can operate stably at frequencies ranging from 5 to 25 Hz when the ignition distance is either 2.30 or 2.70 times the equivalent circle diameter from the thrust wall, and it is found to be better to ignite at a distance of 2.30 times the equivalent circle diameter. The blockage ratio of the lower arc surface is larger than that of the other surfaces. This results in more intense collision and reflection. A larger local high pressure area forms near the lower arc surface, which is conducive to the formation of detonation waves. However, the larger blockage ratio makes the flow loss larger, which weakens the intensity of the pressure waves near the lower arc surface. The detonation waves in the fanshaped PDC travel closer to the upper arc surfaces.

关键词： Fan-shaped pulse detonation combustor Operating characteristic Ignition distance detonation wave

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Numerical studies on interactions between a centrifugal compressor and the back-propagated pressure waves originated from a pulse detonation combustor

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY 2023年第1期237卷 153-162页

作者： Jie, Lu Lingyi, Wang Hao, Zhang Longxi, Zheng Changxin, Peng Northwestern Polytech Univ Sch Power & Energy 1 Dongxiang Rd Xian 710129 Shaanxi Peoples R China AECC Hunan Aviat Powerplant Res Inst Zhuzhou Peoples R China

In order to investigate the influence of the back-propagated pressure waves originated from a pulse detonation combustor on the operating characteristics of the compressor in the pulse detonation turbine engine, a model consist of a centrifugal compressor and an isolation section which was usually utilized to decrease the peak value of the back-propagated pressure waves was set up. Numerical simulations were carried out to study the interactions between the centrifugal compressor and the back-propagated pressure waves under different operating conditions. The matching characteristics of the compressor under the influence of the back-propagated pressure waves were analyzed in a detonation cycle. The results showed that the back-propagated pressure waves would push the shock wave in the isolator towards the throat position, but the shock wave did not pass through the throat for the compressor corrected speed of n = 100% and n = 105%. For these two cases, the back-propagated pressure waves were completely isolated and the operating characteristics of the compressor were the same as those under the steady outlet conditions. For the corrected speed of n = 50% and n = 90%, the shock wave in the isolator section was pushed out of the throat and the supersonic flow in the isolator section was destroyed under the influence of the back-propagated pressure waves. The back-propagated pressure waves would propagate upstream into the compressor. Consequently, the instantaneous mass flow rate and the torque acting on the centrifugal impeller was decreased. The work required by the compressor was also reduced. The equivalent isentropic efficiency of the compressor was decreased. The separation or backflow in the compressor caused by the back-propagated pressure waves would results in an equivalent isentropic efficiency loss of 3.2% points for the case of n = 90% and 15.6% points for the case of n = 50%.

关键词： Centrifugal compressor back-propagated pressure waves operating characteristics pulse detonation combustor

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Numerical studies on detonation wave in hydrogen-fueled pulse detonation combustor with shrouded ejector

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JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2023年第2期45卷 1-15页

作者： Debnath, Pinku Pandey, K. M. Natl Inst Technol Agartala Dept Mech Engn Agartala 799046 Tripura India Natl Inst Technol Silchar Dept Mech Engn Silchar 788010 Assam India

The present paper deals with the unsteady compressible (Ma > 0.3) reacting flows of hydrogen-air mixture in pulse detonation combustor. In order to achieve the potential thrust gain from PDE combustor, the shrouded ejector is placed at exit section of detonation tube. In this analysis, core diameter and ejector length effect on vortex generation has been investigated. Furthermore, the propagation of detonation combustion wave is analyzed for three equivalence ratio (ER) of lean, stoichiometric and rich (phi < 1, phi = 1, phi > 1) in multiple pulse time. Not only the reacting flow structure but also the propulsive performance of pulse detonation combustor has been investigated. Moreover, this numerical simulation is carried out to minimize the fuel consumption in instantaneous pulse time for fully developed detonation wave. The eddy dissipation combustion model with a single-step Arrhenius chemical kinetics model is used to simulate the fuel-air reacting mixture in Ansys fluent platform. The contour plot clearly shows formation number of 2.39 has more significance role for vortex core generation with shortest possible time of 0.033 s. The pickup flame propagation speed of 2310 m/s is obtained, and this magnitude is higher than C-J velocity. The result also indicates that minimum pollutant number is released from lean and rich mixture combustion;even, marginal thrust is generated with magnitude of 35 N and 37 N, respectively, from equivalence ratio of phi = 0.64 and phi = 1.4 at pulse time of 0.033 s. Although the maximum pollutant number of 0.0489 is found from phi = 1.0, strong thrust is obtained from stoichiometric H-2-air mixture.

关键词： Shrouded ejector Computational fluid dynamics pulse detonation combustor Vortex detonation

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Suppression of the back-propagated pressure waves originated from a liquid-fueled valveless pulse detonation combustor with combined aero-valves

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ACTA ASTRONAUTICA 2022年 197卷 269-279页

作者： Lu, Jie Zheng, Longxi Tan, Wenghao Peng, Changxin Zhang, Hao Northwestern Polytech Univ Sch Power & Energy Xian 710072 Peoples R China AECC Hunan Aviat Powerplant Res Inst Zhuzhou 412002 Peoples R China

In order to seek out a way to isolate the back-propagated pressure waves originated from a valveless pulse detonation combustor (PDC), a liquid-fueled single tube PDC was designed and tested at frequencies ranging from 10 Hz to 30 Hz with different types of aem-valve installed at the air inlet such as wedge-shaped aero-valves, reflux-typed aero-valves and combined valves. The damping ability of the aero-valves were quantified and compared. Then, an isolator was designed and combined with the optimized aero-valves to isolate the back-propagated pressure waves. The experimental results show that both the wedge-shaped aero-valve and the reflux-typed aem-valve could reduce the peak value of the back-propagated pressure waves and the pressure oscillation at the air inlet. The largest pressure oscillation was reduced from (74.7 +/- 3.35)% to (25 +/- 1.84)% when three wedge-shaped aero-valves was installed at the inlet section, while the pressure oscillation was only (22.3 +/- 2.9)% with three reflux-typed aero-valves. What's more, the pressure oscillation at the air inlet could be further reduced with the combination of the wedge-shaped aero-valve and the reflux-typed aem-valve. The combined structure 6 (one wedge-shaped aero-valve + two reflux-typed aero-valves) was the most effective way to reduce the pressure oscillations at the air inlet even though the peak value of the back-propagated pressure waves at the air inlet for the combined structure 6 were the highest. When an isolator was installed on the base of the combined structure 6 and the structure F (three reflux-typed aero-valves), the back-propagated pressure waves could be isolated under the case of high inlet total pressure such as a firing frequency of 30 Hz. But there are still pressure oscillations for the firing frequencies lower than 25 Hz because of that there is no supersonic region in the air inlet or the Mach number of supersonic regions is very small at low firing frequencies.

关键词： pulse detonation combustor pulse detonation turbine engine Back-propagated pressure waves Aero-valves Isolator

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Numerical analysis of detonation combustion wave in pulse detonation combustor with modified ejector with gaseous and liquid fuel mixture

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JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 2021年第6期145卷 3243-3254页

作者： Debnath, Pinku Pandey, K. M. Natl Inst Technol Agartala Dept Mech Engn Agartala 799046 Tripura India Natl Inst Technol Silchar Dept Mech Engn Silchar 788010 Assam India

The detonation combustion phenomenon is supersonic combustion process and follows on thermal explosion in combustor. Deflagration to detonation transition occurs in detonation tube due to pressure oscillation in PDE combustor, which is driven by acoustic combustion phenomena in detonation tube. As this combustion process has great significance role for future propulsion system, the present objective is to investigate the effect of modify ejector having half angles of alpha = (- 4 degrees, 0 degrees, + 4 degrees) on detonation combustion wave propagation regime. Further the propulsion thrust of liquid kerosene and gaseous hydrogen-air mixture are also analyzed. This numerical simulation has been analyzed by LES turbulence model for DDT and shock wave pressure oscillation in pulse detonation combustor at Fluent based CFD plat form. The one-step irreversible chemical kinetics model analyzes the details exothermic chemical reaction mechanism inside the combustor. However, the shrouded ejector with taper angle of alpha = +4 degrees performed the strong starting vortex generation and shortest possible time of 0.032 s for fully developed detonation wave. The simulation results also shows that thrust force augmentation of hydrogen-air mixture is greater compared to combustion process of liquid kerosene-air mixture with significant magnitude of 38 N. Although kerosene-air mixture produces less pollutant number but the propagation flame velocity is 2550 m s(-1)for hydrogen/air mixture, which is near aboutC-Jvelocity and comparatively higher than kerosene/air combustion process.

关键词： Shrouded ejector Computational fluid dynamics pulse detonation combustor Vortex ring detonation

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Isolation of back pressure waves in a valveless pulse detonation combustor with inlet air of high total temperature

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FUEL 2023年第Part2期331卷

作者： Jie, Lu Hao, Zhang Wenhao, Tan Longxi, Zheng Northwestern Polytech Univ Sch Power & Energy Xian 710072 Peoples R China

In order to achieve the effectively isolation of back pressure waves in a valveless pulse detonation combustor (PDC) within a short axial distance, a combined aero-valve was designed and tested with a single tube PDC at firing frequencies from 10 Hz to 25 Hz. Nozzles of different size were designed to adjust the bleeding air of the combined aero-valve. The nozzles' effect on the isolation of the back pressure waves were discussed. Numerical simulations were carried out to reveal interactions between the back pressure waves and the combined aero-valve. The experimental results proved that the combined aero-value was effective in isolating the back pres-sure waves at firing frequencies from 10 Hz to 25 Hz for the baseline case. When a smaller nozzle was installed, the combined aero-valve would lose the ability to isolate the back pressure waves at low firing frequencies. Numerical simulations showed that the supersonic flow in the shock isolator channel was the key factor to realize completely isolation of the back pressure waves. For the cases with pressure oscillations appeared at the inlet of the isolation section, the back pressure waves would push the shock wave out of the channel and destroy the supersonic flow in the shock isolator channel, while the supersonic flow did not disappear for the cases when the back pressure waves were completely isolated, the shock wave in the shock isolator channel was just pushed forward a certain distance and would recover to the initial position as the filling process of the PDC started.

关键词： pulse detonation turbine engine pulse detonation combustor Shock wave Back pressure waves

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Experimental Investigations on detonation Initiation Characteristics of a Liquid-Fueled pulse detonation combustor at Different Inlet Air Temperatures

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ENERGIES 2022年第23期15卷 9102-9102页

作者： Tan, Wenhao Zheng, Longxi Lu, Jie Wang, Lingyi Zhou, Daoen Northwestern Polytech Univ Sch Power & Energy Xian 710072 Peoples R China

The detonation initiation characteristics of a single tube liquid-fueled pulse detonation combustor (PDC) is investigated at different inlet air temperatures in this paper. The inner diameter of the PDC is 62 mm. Gasoline and air are used as fuel and oxidant, respectively. The inlet air temperature is 288-523 K and the operating frequency of the PDC is 10 similar to 30 Hz. The experimental results show that the deflagration to detonation transition (DDT) distance, detonation initiation time, DDT time and jet ignition time decrease with the increasing operating frequency at the same inlet temperature. When the inlet temperature is 288 K, the DDT distance is shortened from 860.5 mm to 787.7 mm as the operating frequency increases from 10 Hz to 30 Hz. The detonation initiation time, the jet ignition time and the DDT time are reduced from 10.01 ms, 7.66 ms and 2.35 ms to 6.55 ms, 4.99 ms and 1.56 ms, respectively. When the inlet air temperature increases, the atomization and evaporation of the gasoline is improved, which also leads to the decrease in the DDT distance, the detonation initiation time, the jet ignition time and the DDT time. For example, when the inlet air temperature increases from 288 K to 523 K at the frequency of 10 Hz, the DDT distance is shortened from 860.5 mm to 747.2 mm and the detonation initiation time, the jet ignition time and the DDT time is reduced to 5.867 ms, 2.51 ms and 1.11 ms, respectively. Additionally, the self-ignition caused by high inner wall temperature occurs when PDC is operating at high frequency under high inlet air temperature.

关键词： two-phase detonation pulse detonation combustor DDT distance detonation initiation time self-ignition

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Optical Measurement of Fluid Motion in Semi-Valveless pulse detonation combustor with High-Frequency Operation

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COMBUSTION SCIENCE AND TECHNOLOGY 2020年第2期192卷 197-212页

作者： Kubota, Akiya Matsuoka, Ken Kawasaki, Akira Kasahara, Jiro Watanabe, Hiroaki Matsuo, Akiko Endo, Takuma Nagoya Univ Dept Aerosp Engn Nagoya Aichi Japan Keio Univ Dept Mech Engn Yokohama Kanagawa Japan Hiroshima Univ Dept Mech Syst Engn Higashihiroshima Japan

The purge layer of a semi-valveless pulse detonation cycle (PDC) needs to be minimized for operating at a gas-dynamic upper frequency limit. Therefore, it is essential to better understand the process of burned gas backflow for minimizing the purge layer thickness. The flow field of the semi-valveless PDC was visualized to illustrate the movement of burned gas. A combustor of length of 95 mm with a 10-mm-square cross section was used. Supercritical ethylene and oxygen gas were used as fuel and oxidizer, respectively, and the operation frequency was 604 Hz. The unsteady refilling process of the detonable mixture was modeled by an isentropic flow. In addition, the detailed burned gas blowdown process with deflagration-to-detonation transition (DDT) and the backflow were captured. It was shown that the retonation wave generated by the DDT process was the primary trigger of the burned gas backflow. When the duration required for the DDT process was sufficiently shorter than that of the burned gas blowdown process, it was found the latter could be reproduced with approximately 90% accuracy by one-dimensional numerical analysis without the DDT process.

关键词： pulse detonation combustor Semi-valveless pulse detonation cycle High-frequency operation

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