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在脉冲爆震发动机工作过程中,爆震室压力处于强非定常状态。传统的型面不可调尾喷管与可调尾喷管都无法满足爆震室内压力的高频剧烈变化,进而导致较大的推力损失。为了提升现有脉冲爆震发动机型面不可调增推喷管性能,可以从爆震室中引出爆震燃气,通过无阀自适应控制将该二次流喷射在喷管扩张段,实时调节主流的有效扩张面积比,进而形成流体喷管。针对这种形式的流体喷管,在可爆混合物一定(当量比1.0,初始填充压力为0.1 MPa)的情况下,基于二维数值模拟,研究了不同二次流喷注条件(二次流喷注面积比、位置比)对主流流动状态及发动机推进性能的影响。计算结果表明:二次流的喷注改变了喷管有效流通面积;二次流在喷管扩张段喷注面积比越大,喷管的冲量提升率越大(相对于基准喷管冲量最大提升率为5.25%);二次流喷注位置越靠近喷管喉道处,喷管的冲量提升率越高。 相似文献
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建立了氢氧爆震波点火器试验系统,并根据试验塞式喷管发动机工作状态要求设计了爆震波点火器。在高空条件下(0.005 ̄0.002MPa),爆震波点火器供气压力0.3MPa、混合比3左右,对爆震波点火器的点火性能进行了试验,成功实现了高空条件下爆震波点火火炬。在同样高空条件下对爆震波点火器点燃单元塞式喷管试验发动机成功进行了点火试验。试验结果表明,氢氧爆震波点火器能以较低的供气压力实现可靠点火。爆震波点火器在气氢气氧单元塞式喷管试验发动机点火的成功应用,为下一阶段应用于多管塞式喷管发动机的实际点火试验提供了技术基础。 相似文献
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Barkhatov N. A. Korolev A. V. Zastenker G. N. Ryazantseva M. O. Dalin P. A. 《Cosmic Research》2003,41(6):529-538
One-dimensional MHD simulations of solitary sharp and strong disturbances (impulses) of the interplanetary magnetic field and plasma of the homogeneous solar wind were performed. The characteristics of a disturbance of this type, recorded onboard the WIND spacecraft (SC) rather far from the Earth, were taken as initial conditions. The results of numerical experiments simulating the evolution of this disturbance in the moving interplanetary plasma, whose parameters correspond to observations of the WIND and INTERBALL-1 SC, show the efficiency of the computer code developed with the special purpose of investigating low-frequency wave events in the space environment. The calculated characteristics of the impulse resulting from the evolution are in good agreement with parameters of the disturbance recorded by the INTERBALL-1 SC closer to the Earth. In particular, the impulse expands due to imbalance of thermal and magnetic pressures, but keeps its abrupt boundaries. It was demonstrated that stable plasma objects, corresponding to stationary MHD solutions, could really exist in the solar wind plasma for a long time. 相似文献
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Cylindrical heterogeneous detonation waves 总被引:1,自引:0,他引:1
Further experimental studies of blast wave initiated cylindrical heterogeneous (liquid fuel drops, gas oxidizer) detonation waves are described. A pie-shaped shock tube, used for these studies, was altered in certain ways so as to improve the modeling of cylindrical waves. These modifications, along with some operational aspects, are briefly discussed. The breech of the facility, where the blast wave is generated by an explosive, became distorted with usage. Results are presented which show that lower detonation velocities are realized with the damaged breech (other conditions being the same). A photographic and pressure switch wave time of arrival study was made to ascertain the wave shape. Photographs are shown which show that the waves, blast as well as detonation, are close to cylindrical. However, in some cases there is appreciable distortion of the wave front by debris ahead of the wave. Presumably this debris comes from the blasting cap used to ignite the condensed explosive. A series of experiments was conducted using kerosene drops of 388 μm diameter dispersed in air through use of a large number of hypodermic needles. Radial fuel void regions were established by cutting off the fuel flow to a number of needles. Preliminary results relating to the effect of the size of the cloud gap on detonation velocity, quenching, and the initiator energy levels required for detonation are discussed. 相似文献
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固体火箭燃气超燃冲压发动机具有高比冲、结构简单、流量易调节等优点,然而在超音速空气流的补燃室中,如何让燃料更好地与空气掺混,增加颗粒停留时间,在较短时间内释放出更多的燃烧焓成为目前研究的重点。采用Realiazble k-ε湍流模型,单步涡团耗散模型,在King的硼颗粒点火燃烧模型的基础上考虑了硼颗粒在高速气流当中的气动剥离效应,利用龙格-库塔算法迭代计算硼颗粒点火燃烧过程,对燃气进气方向与轴向夹角从45°~180°的10种进气方式下的补燃室进行了三维两相燃烧流动计算,分析了各种进气角下的燃气燃烧效率、硼颗粒燃烧效率以及总燃烧效率。结果表明:当一次燃气喷射角度与轴向夹角逐渐增加时,燃气与颗粒燃烧效率逐渐增加,并在180°时燃烧效率和比冲为最高。 相似文献
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HRM code for the simulation of N2O/HTPB hybrid rocket motor operation and scale effect analysis has been developed. This code can be used to calculate motor thrust and distributions of physical properties inside the combustion chamber and nozzle during the operational phase by solving the unsteady Navier–Stokes equations using a corrected compressible difference scheme and a two-step, five species combustion model. A dynamic fuel surface regression technique and a two-step calculation method together with the gas–solid coupling are applied in the calculation of fuel regression and the determination of combustion chamber wall profile as fuel regresses. Both the calculated motor thrust from start-up to shut-down mode and the combustion chamber wall profile after motor operation are in good agreements with experimental data. The fuel regression rate equation and the relation between fuel regression rate and axial distance have been derived. Analysis of results suggests improvements in combustion performance to the current hybrid rocket motor design and explains scale effects in the variation of fuel regression rate with combustion chamber diameter. 相似文献
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液体亚燃冲压发动机性能分析研究 总被引:1,自引:0,他引:1
随着巡航导弹的作战空域和飞行速度的不断增大,对液体亚燃冲压发动机的性能要求越来越高,亟待对冲压发动机性能的影响因素进行分析研究.通过对液体亚燃冲压发动机的工作过程进行详细的分析研究,编制了冲压发动机性能计算软件,利用该软件分析冲压发动机的各个关键组合件,如进气道、燃烧室、尾喷管以及燃油供应系统等各个组合件的性能对冲压发... 相似文献
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固冲发动机补燃室二次燃烧实验研究 总被引:2,自引:0,他引:2
采用不确定度评定的地面直连冲压实验设备,对某全尺寸固冲发动机补燃室二次燃烧进行了实验研究。通过测定比冲效率,确定了不同的燃气发生器喷嘴结构、空气进气角度、进气头部距离和补燃室长度对二次燃烧的影响,并进行了机理分析。结果表明,五喷嘴比冲效率较高,燃气的切入方式对补燃室二次燃烧有重要影响;增大入射角度,可提高比冲效率,但加剧了燃烧产物在补燃室内的沉积;补燃室头部距离不宜过大,比冲效率不随头部距离线性增加;补燃室长度增加,可使比冲效率提高,但效果并不理想。 相似文献
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高速气流场燃油雾化液滴分布数值研究 总被引:2,自引:0,他引:2
针对亚燃冲压发动机燃烧室内部流动特点,结合二元稳定器试验台高速气流场燃油雾化特性试验,建立试验件三维模型并对其喷雾两相流动进行数值模拟。主要研究了来流马赫数以及喷嘴条件变化时燃油雾化液滴与油气比的分布。分析认为,来流马赫数的增加使得雾化特征角缩小,可同时改善燃油蒸发并获得更加均匀的油气比分布。随着供油压力的提高,离心式与直流式喷嘴雾化特征角均增大,但供油压力不是影响直流喷嘴雾化锥角的主要因素。计算结果与试验结果对比定性符合良好,定量误差范围可以接受,验证了计算模型与计算方法的正确性,所得到的结果可应用于工程设计。 相似文献
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A two-dimensional axis symmetrical model for multi-phase turbulent combustion simulation has been developed in a magnesium-based fuel ramjet, the stochastic model is applied to track the motion and transportation of discrete phase in the whole flow field in Lagrangian frame. Firstly, the flow field parameters distribution including temperature, velocity, Mg particle burning rate, main components are obtained to describe the basic operating characteristics, and the thermoacoustic oscillation during the combustion process is predicted due to the observed vortex. Then combined with the developed thermodynamic calculation program, the influencing rules of water/fuel ratio and magnesium-based fuel composition ratio on ramjet operating characteristics are analyzed. The results obtained show that the distribution of two water/fuel ratios exerts a direct impact on the temperature fluctuations in combustor, further influences the combustion stability, as for theoretical specific impulse, a maximal value is observed along with the total water/fuel ratio, while the monotonous trends for thermal efficiency and propulsive efficiency are achieved respectively. Moreover, the magnesium-based fuel composition ratio is a dominant factor to influence the operating characteristics, and it is proved that the high-proportion Mg in fuel is beneficial to specific impulse augment through validation of both simulation results and thermodynamic calculation results. 相似文献
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Charles K. Westbrook 《Acta Astronautica》1978,5(11-12)
Flame propagation through stratified media is examined with a numerical model of chemically reactive flow in combustion systems. The model includes a detailed reaction mechanism for methane combustion and an implicit Eulerian difference equation form for the hydrodynamics. Calculations of flames propagating through spatially uniform and stratified media are compared. Results are presented which indicate that hydrodynamic factors can have a significant effect on the energy production rates, pressure rise rates, and unburned fuel concentrations for all models. For the stratified charge models it was found that CO and NOx production rates were significantly lower than for uniform charge models. Significant amounts of unburned fuel are found near the combustion chamber wall, even in some of the stratified charge models, so that reaction quenching at the wall may be important even in the stratified charge cases. Calculations are presented which predict improvements in fuel efficiency and decreases in pollutant formation, resulting from changes in fuel stratification and compression ratio. 相似文献
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连续爆轰发动机的研究进展 总被引:3,自引:0,他引:3
连续爆轰发动机是一种基于爆轰波将推进剂的化学能转化成热能的新概念发动机,近年来受到世界各主要国家的高度关注。现已成功获得多种燃料长时间稳定的连续爆轰,较深入地认识了连续爆轰流场结构,初步测得推力和比冲,验证了连续爆轰发动机的性能优势并在火箭模态、冲压模态以及涡轮模态下都实现了稳定连续爆轰。对连续爆轰发动机的工作原理,以及近年来世界各主要国家在连续爆轰发动机的基础研究和应用研究方面取得的代表性成果进行了综述,并给出尚待解决的问题,为其进一步工程化应用提供参考。 相似文献