共查询到17条相似文献,搜索用时 187 毫秒
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《固体火箭技术》2017,(1)
针对涡轮增压器出口气流进入涡轮增压固冲发动机(Turbocharged Solid Propellant Ramjet,TSPR)补燃室后,因同轴流动而造成掺混燃烧效率不高的问题,通过对比研究ATR(Air Turbocharged Ramjet)及固冲发动机掺混燃烧增强手段,形成了一种可有效增强TSPR补燃室掺混燃烧效果的方案。继而通过数值模拟的手段对该方案的有效性和内在机理进行了讨论。最后通过TSPR工作模式的数值模拟,发现在不同富燃燃气余气系数状态下补燃室效率均能保持90%以上,验证了该方案的有效性和适用性。根据这些研究,该文认为保留驱涡燃气高速旋流配合增压空气采用一定射流角度进入燃烧室的出口流动方式能够使TSPR补燃室有效工作,燃烧效率相对原有ATR模式能够提高1倍以上;其中涡轮的旋转速度高于40 000 rpm时,经过涡轮膨胀做功的驱涡燃气使发动机比冲和补燃室温度分布情况都比较理想;增压空气采用40°~50°的射流角进行斜向射流对发动机比冲性能提高和补燃室内温度分布改善是比较有利的。 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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通过数值模拟的方法从冷态方面研究了金属/水反应冲压发动机二次掺混室内横流气体和通过压力旋流喷嘴雾化的液滴群的掺混情况.提出了掺混度、不均匀浓度因子和等浓度线这3种特征量作为评价指标,分析了不同喷嘴入射角度情况下,液滴群对横向交叉气流的影响以及气流对液滴群掺混的作用.结果表明,液滴群的加入使气流中产生了尺度不同的涡,促进了湍流;喷嘴附近的掺混初始阶段,大涡作用使液滴分布很不均匀,喷嘴下游,涡的尺度减小,对液滴的扩散影响减弱,但初始的喷雾形态和液滴趋向高应变和低涡量区域造成了壁面处液滴浓度仍然高于其他区域;喷嘴垂直无偏入射的掺混优于轴向或切向入射;轴向向上游偏转入射优于向下游偏转入射;切向偏转角度越大,越不利于掺混. 相似文献
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《中国航天(英文版)》2016,(1)
This paper focused on the fundamental and applied research of turbulent flows encountered in the hypersonic flight of aerospace vehicles,which take place in the boundary layer and mixing layer.As to the plate boundary layer,LES approach has been used to simulate the flows over compression corners and incident shock waves,revealing that turbulent flows would significantly inhibit the boundary layer separation caused by shock wave-boundary layer interaction(SWBLI).The boundary layer transition over a circular cone has been analyzed through stability analysis and wind-tunnel test,by which the angle-of-attack effect in case of small angle of attack has been studied.Non-linear evolution process and secondary instability structure in the supersonic mixing layer(Mc=0.5) were initially figured out through the study of mixing layer,and knowledge of the flow control mechanism of the boundary layer and mixing enhancement mechanism of the mixing layer has been obtained through this research.Artificial boundary-layer transition technique based on subharmonic resonance has been proposed and applied to the flow control in a scramjet inlet,inhibiting the flow separation of the boundary layer while improving the inlet performance.To guarantee the mixing of kerosene and supersonic airflow in the scramjet combustor,the mixing enhancement method based on subharmonic resonance has been adopted and a concept of combustor with smooth wall and low internal drag has been proposed for ignition and stable combustion.Finally,future turbulence research and technological development of aerospace vehicles is predicted. 相似文献
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《Acta Astronautica》2014,93(1):298-310
Numerical simulations were employed to analyze the flowfield of a scramjet with three-dimensional (3D) sidewall compression inlet, and the effect of inlet distortion on the mixing and combustion process was examined. The numerical approach solved the compressible Reynolds Averaged Navier–Stokes (RANS) equations supplemented with a finite rate chemical reacting model for the combustion of hydrogen fuel and air. Turbulence closure was achieved using Menter shear-stress transport (SST) model. To verify the accuracy of the simulation, the computed wall pressure was compared with the experimental data of the direct-connect combustor test. The metrics employed in the simulations included qualitative assessments related to flow structure as well as quantitative values of fuel mixing efficiency, combustion efficiency and static pressure distribution. Intake sidewalls were found to strongly affect the inlet flow structure, which became more complex in the nonuniform flowfield. The shock train system affected the combustion region located upstream of the injection and led to pairs of asymmetric separation bubbles. Nevertheless, the shock train system dissipated due to the reactions, the combustion patterns of each fuel jets in downstream region were nearly identical, and the degree of improvement of mixing and combustion efficiency near the downstream injectors was less than that near the upstream injectors. 相似文献
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展向行波状Lorentz力的波数对壁湍流控制的影响 总被引:2,自引:0,他引:2
展向行波状Lorentz力可以有效调制湍流近壁流动及减少壁面摩擦阻力。为了解行波波数在壁湍流控制中的影响,并进一步揭示该方法的减阻机理,本文利用Fourier-Chebyshev谱方法,通过直接数值模拟(DNS),对槽道湍流的展向行波状Lorentz力控制和减阻问题进行了研究,讨论了展向波数kz对近壁流动及壁面阻力的影响。结果表明,当展向行波状Lorentz力诱导的流场被用来调制固有的近壁湍流流场时,固有流场和诱导流场同时受到调制。Lorentz力的展向波数对流场调制效果具有显著影响。通过波数的选择,引进新的涡结构,可以调制条带结构的展向间距与强度,影响近壁流体的湍流猝发活动,从而调制壁面摩擦阻力的大小。 相似文献
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A comparison between two analytical models of a free turbulent mixing of reacting streams with finite chemical reaction rates is presented and the results of calculations compared with experimental data. The substance is a mixture of the inert non-dissociated nitrogen and oxygen that dissociates and reacts with hydrogen.For the first model the local values of flow parameters along the streamlines were provided by the numerical solution of the conservation equations in the boundary layer form for a multicomponent mixture of perfect gases in the von Mises coordinate system. In the course of this analysis the problem was treated by dividing the flowfield into a large number of regions and by solving the Cauchy problem of the conservation equations for each region.The second analytical model was based on the ignition delay to describe the chemistry in the region of pre-ignition. The external air stream was heated by combustion and the influence of the water vapor and the intermediate species on the reaction kinetics in the mixing zone was numerically investigated.The results of calculation are compared with the experimental data with respect to the location of a visible flame edge under combustion of hydrogen jet in the co-current flow. 相似文献