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Tribological properties of low-temperature time-dependent pretreated graphite for mechanical seal pairs in high-speed turbopump

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Friction 2024年第2期12卷 305-318页

作者： Yangyang ZHAO Guoyuan ZHANG Junqian WANG He WANG Weigang ZHAO Qunfeng ZENG School of Mechano-Electronic Engineering Xidian UniversityXi’an 710071China Xi’an Aerospace propulsion Institute Xi’an 710071China Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong UniversityXi’an 710049China

The friction coefficient and wear rate of pretreated graphite with liquid nitrogen were obtained by using a ball-on-disk tester,and the wear of GCr15–graphite seal pairs with the low-temperature time-dependent pretreatment was discussed by comparing the wear *** results show that liquid nitrogen pretreatment can affect the hardness and interlayer spacing of *** range of the friction coefficients of pretreated graphite changes from 0.17 to *** the increase of liquid nitrogen pretreatment time,the wear mechanism of graphite would change from dominated three-body wear to adhesion *** experimental results of the mechanical seal with liquid nitrogen pretreatment show that the wear rate of stator is less than 0.00165 mm^(3)·N^(−1)·m^(−1),and the graphite shows a good low-temperature compatibility.

关键词： graphite low-temperature pretreatment mechanical seal friction and wear

Experimental research on rotating detonation with liquid hypergolic propellants

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Chinese Journal of Aeronautics 2018年第12期31卷 2199-2205页

作者： Shuaijie XUE Hongjun LIU Lixin ZHOU Weidong YANG Hongbo HU Yu YAN Science and Technology on liquid Rocket Engine Laboratory Xi'an Aerospace Propulsion Institute

This paper describes experimental research into the initiation and propagation of rotating detonation for liquid Nitrogen TetrOxide(NTO) and liquid MonoMethylHydrazine(MMH).An annular rocket-type combustor without nozzle was designed to investigate detonation combustion. The propellants were injected through unlike impingement injectors. The combustion flame fronts and pressure waves were detected using optical diagnostics and dynamic pressure sensors,respectively. The propagation of rotating detonation was established spontaneously by increasing the mass flow rate of propellants. The velocity of propagation of the flame fronts and pressure waves was nearly equal and reaches supersonic speed. Two different detonation combustion patterns are present, single wave mode and double waves mode. And in double waves mode, the two detonation waves are always counter-rotating. The possibility of rotating detonation initiation in a combustor with nozzle was also checked. Stable rotating detonation can be initialized and sustained at similar operating conditions.

关键词： Hypergolic Initiation liquid propellant Nozzle Rotating detonation

Periodic atomization characteristics of an impinging jet injector element modulated by Klystron effect

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Chinese Journal of Aeronautics 2018年第10期31卷 1973-1984页

作者： Anlong YANG Bin LI Shangrong YANG Yunfei XU Longfei LI Science and Technology on liquid Rocket Engine Laboratory Xi'an Aerospace Propulsion Institute

An experimental study on the Klystron effect of periodic injection modulated by pressure drop fluctuations on subsequent atomization is conducted. Time-resolved atomization backlit images and atomization Mie scatter images are captured by using the high speed camera. It is found that periodicity of forced atomization relies on pressure drop fluctuation amplitude and phase differences between atomization and pressure drop fluctuations relate to fluctuation frequencies. This feature of periodic atomization induced by Klystron effect corresponds to periodicities and high amplitudes of pressure fluctuations in unstable combustion chambers and chaos and low amplitudes of pressure fluctuations in stable combustions chambers. Drastically periodic varying of gross surface area of droplets with time was shown in Mie scatter images. The importance of periodic impinging jet atomization modulated by pressure drop fluctuations for acoustic liquid propellant combustion instabilities is illustrated.

关键词： Atomization Combustion stability Impinging jet injector Klystron effect liquid rocket engine Mie scatter

Periodic atomization characteristics of simplex swirl injector induced by klystron effect

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Chinese Journal of Aeronautics 2018年第5期31卷 1066-1074页

作者： Anlong YANG Shangrong YANG Yunfei XU Longfei LI Science and Technology on liquid Rocket Engine Laboratory Xi'an Aerospace Propulsion Institute

The atomization dynamic characteristics of a simplex swirl injector was investigated experimentally by using a hydrodynamic mechanical pulsator and the shadow photography technique. The frequency response characteristics of the fluid film and atomization fluctuations and their correlations with pressure fluctuations were obtained by using an in-house code of image processing. It is demonstrated that the klystron effect induced by periodic pressure fluctuations results in periodic liquid film fluctuation with large amplitudes, periodic superposition of droplets and reduction of the breakup length. It was found that the atomization of the simplex swirl injector only responds to the pressure fluctuation in frequency range approximately from 0 to 300 Hz, and it is particularly sensitive to pressure fluctuations at frequencies from 100 to 200 Hz. According to this experiment, the responsive frequency limitation is merely affected by injector configuration, rather than the supply line.

关键词： Atomization Combustion stability Klystron effect liquid rocket engine Simplex swirl injector

Research on shell-side heat and mass transfer with multi-component in LNG spiral-wound heat exchanger under sloshing conditions

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Petroleum Science 2024年第2期21卷 1333-1345页

作者： Xue-Ping Du Guang-Lei Yu Ya-Cheng Xu Zhi-Jie Chen Nai-Liang Li Huan-Guang Wang School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina Key Laboratory of Thermo-Fluid Science and Engineering MOEXi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Aerospace propulsion Test Technology Institute Xi'an710100ShaanxiChina

The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure *** results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.

关键词： Spiral-wound heat exchanger Sloshing conditions Two-phase flow Multi-component Heat and mass transfer

Experimental of combustion instability in NTO/MMH impinging combustion chambers

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Chinese Journal of Aeronautics 2020年第5期33卷 1476-1485页

作者： Anlong YANG Bin LI Yu YAN Shuaijie XUE Lixin ZHOU Science and Technology on liquid Rocket Engine Laboratory Xi’an Aerospace Propulsion InstituteXi’an 710100China

This paper presents an experimental study into dynamics of chamber pressure and heat release rate during self-excited spinning and standing azimuthal mode in NTO/MMH (nitrogen tetroxide/monomethylhydrazine) impinging combustion *** cases including two combustion chamber configurations were *** operating conditions of all unstable cases were located in the instability region according to Hewitt empirical *** results show that chamber pressure oscillations keep pace with the corresponding OH*chemiluminescence intensity over the whole combustion region in the spinning and standing *** is indicated that the Rayleigh index is positive over the whole combustion area in all the unstable cases.A significant supersonic flame front structure of the first-order spinning mode was found in a cylindrical chamber,which means that a detonation wave could exist in the cylindrical chamber without a center *** pressure and heat release rate oscillations at the pressure node are nonnegligible although their amplitudes are lower than those at the pressure antinode in the first-order standing mode with an annular ***,the dominant frequency of pressure and heat release rate oscillations at the pressure node is twice as high as that at the pressure antinode.

关键词： Atomization Combustion stability Impinging jet injector Klystron effect liquid rocket engine

Experimental investigation of cavitation instabilities in inducer with different tip clearances

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Chinese Journal of Aeronautics 2021年第9期34卷 168-177页

作者： Le XIANG Yonghua TAN Hui CHEN Kaifu XU Science and Technology on liquid Rocket Engine Laboratory Xi’an 710100China Academy of Aerospace propulsion Technology Xi’an 710100China Xi'an Aerospace propulsion Institute Xi’an 710100China

To investigate the effect of tip clearance size on cavitation characteristics in a turbopump inducer,a series of experiments have been conducted in a newly developed visualization test facility using room temperature water as working *** pressure fluctuations near the tip region were collected,and the cavity structures under various conditions were documented by a high-speed *** is found that large tip clearance distinctly reduces both the non-cavitation and cavitation *** cavitation instabilities,super-synchronous rotating cavitation,synchronous rotating cavitation and cavitation surge have been carefully identified through combination of cross-correlation analysis of pressure signals and visualization *** tip clearance displays a remarkable stabilization effect on pressure fluctuation,cavitation surge totally disappears,and the range of occurrence of synchronous rotating cavitation becomes smaller for the large tip clearance,whereas super-synchronous rotating cavitation only occurs in the large tip *** cavitation areas are smaller at large tip clearance,while the flow channels are more seriously choked when cavitation occurs heavily in comparison with those at small tip clearance,which may be responsible for the worse cavitation performance.

关键词： Cavitation instabilities Inducer Pressure fluctuation Tip clearance Visualization

Microstructure and Mechanical Properties of Friction Stir Lap Welded Aluminum Alloy AA2014

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Journal of Materials Science & Technology 2012年第5期28卷 414-426页

作者： S. Babu G.D. Janaki Ram P.V. Venkitakrishnan G. Madhusudhan Reddy K. Prasad Rao Dept. of Metallurgical and Materials Engineering Indian Institute of Technology Madras Chennai India liquid propulsion systems Centre Indian Space Research Organisation Tiruvananthapuram India Defence Metallurgical Research Laboratory Hyderabad India

Friction stir lap welds were produced in 3 mm thick Alclad sheets of Al alloy 2014-T4 using two different tools （with triangular and threaded taper cylindrical pins）. The effects of tool geometry on weld microstructure, lap-shear performance and failure mode were investigated. The pin profile was found to significantly influence the hook geometry, which in turn strongly influenced the joint strength and the failure mode. Welds produced in alloy 2014-T4 Alclad sheets by using triangular and threaded taper cylindrical tools exhibited an average lap-shear failure load of 16.5 and 19.5 kN, respectively, while the average failure load for standard riveted joints was only 3.4 kN. Welds produced in alloy 2014-T6 Alclad sheets and in alloy 2014-T4 bare sheets （i.e., no Alclad） were comparatively evaluated with those produced in alloy 2014-T4 Alclad sheets. While the welds made （with threaded taper cylindrical tool） in T6 and T4 conditions showed very similar lap-shear failure loads, the joint efficiency of the welds made in T6 condition （43%） was considerably lower （because of the higher base material strength） than those made in T4 condition （51%）. The Alclad layers were found to present no special problems in friction stir lap welding. Welds made with triangular tool in alloy 2014-T4 Alclad and bare sheets showed very similar lap-shear failure loads. The present work provides some useful insights into the use of friction stir welding for joining Al alloys in lap configuration.

关键词： Aluminum alloys Friction stir welding Lap joints Lap-shear testing

Medium independent jet(MI-Jet)engine

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propulsion and Power Research 2020年第3期9卷 240-254页

作者： Prajith Kumar K.P. Aravind Vaidyanathan Indian Institute of Space Science and Technology ThiruwvananthapuramKerala695547India liquid propulsion System Centre ThinwvananthapuramKerala695547India

MI-Jet or medium independent jet engine is a new conceptual design which can be used in any gaseous atmosphere or in any planets with an ISP greafer than that of the existing rocket *** engine's thermodynamic concept could be utilized to develop turbojet,ramjet and scramjet engines that can operate in Martian environment with higher *** same concept could be extended for the development of MI-Turbojet,M-Ramjet and MI-Scramjet engine for Earth atmosphere with an ISP as high as 200% of the ISP of existing rocket engines,but less than that of the conventional scramjet or other air-breathing *** the operational complexity of the MI-Jet will be significantly lower than that of the existing scramjet engine.

关键词： Medium independent jet engine Martian transportation MI-Scramjet External combustion-propulsion