共查询到20条相似文献,搜索用时 203 毫秒
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引射器入口形状对PDE的性能影响实验 总被引:1,自引:0,他引:1
对具有两种不同进气口形状的脉冲爆震发动机(PDE)引射器增推性能进行了实验研究.实验采用汽油为燃料,空气为氧化剂.文章设计了六组具有不同直径,不同引射器入口形状的圆柱型引射器.实验采用力传感器法对具有圆形和收敛形入口形状的引射器的增推性能进行了实验研究.结果发现脉冲爆震发动机加引射器后的增推性能均有明显的改善.在引射器长径比一定的情况下,采用收敛型进气口的引射器普遍比采用圆形进气口结构的引射器增推效果明显.当引射器位于主爆震管的上游时,直径比为2.5引射器相对其它引射器具有更高的推力增益,最大可达80.5%. 相似文献
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涡扇-脉冲爆震组合发动机内外涵掺混器研究 总被引:1,自引:0,他引:1
在涡扇发动机基础上,以脉冲爆震燃烧室代替普通加力燃烧室构成涡扇-脉冲爆震组合发动机.对该组合动力,涡扇发动机内外涵掺混过程对脉冲爆震燃烧室的进气状况有着重要的影响,本文针对环形混合器和波瓣混合器进行了数值模拟,揭示了两种混合器不同的掺混机理,同时研究了不同穿透率的波瓣混合器对流场的影响.结果表明,相对于环形混合器,采用波瓣混合器能够获得良好的掺混效果和PDE入口温度的提高;但随着穿透率的增加,波瓣混合器总压损失也会增加,同时PDE入口的氧气浓度也有所降低. 相似文献
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流体推力矢量技术可为超声速无尾布局提供良好的隐身性能与纵向操纵力矩,具有响应快、质量小等优势。旁路式激波矢量喷管无须从发动机引气,克服了为增加矢量角而增加发动机引气流量的问题,可降低发动机的负担。开展了引气位置对旁路式二元激波矢量喷管矢量性能影响研究,为加深对此种喷管性能理解以及将其实用化打下基础。结果表明:喉道引气喷管兼具激波矢量和喉道偏斜法的特征,入口引气喷管在过膨胀状态下性能更好,喉道引气喷管在欠膨胀状态下更有优势。射流后的分离模式显著影响喷管矢量性能,闭式分离使喷管矢量性能下降明显,喉道引气喷管矢量性能突变对应的落压比小于入口引气喷管。实际应用中,应避免分离模式由开式分离转为闭式分离,根据不同膨胀状态搭配不同的旁路式引气方式能够最大化旁路式二元激波矢量喷管性能。 相似文献
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煤油/空气脉冲爆震发动机激波反射起爆研究 总被引:2,自引:0,他引:2
为了研究煤油/空气脉冲爆震发动机爆震室内激波遇到障碍物发生反射促使PDE通常完成爆燃向爆震转变的起爆技术,设计加工了环型孔板和双半V型楔面体,并安装在内径100 mm的爆震管内,进行了多循环爆震试验,成功实现了煤油/空气脉冲爆震发动机工作频率30 Hz稳定工作,获得稳定传播的爆震波.研究结果表明:在爆震室内安装合理结构的障碍物能够有效提高激波反射,缩短爆燃向爆震转变的距离(时间),成功获得稳定传播的爆震波.研究结果为优化设计煤油/空气脉冲爆震发动机原理样机提供了初步理论基础. 相似文献
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基于爆震燃烧的推进技术是未来空间技术的重要发展趋势,特别是可实现结构简单化设计和高热力学效率.针对火箭式连续旋转爆震发动机、吸气式爆震发动机的实验测试和数值仿真,文章综述了其国内外研究进展,分别总结了不同燃料、燃烧室结构、喷注方式以及工作方式等对连续旋转爆震波的传播规律和发动机的特性影响规律.虽然上述探索性研究得到了诸多有益的结论,但是由于连续旋转爆震燃烧技术涉及的流动、物理化学过程十分复杂,对旋转爆震燃烧的机理研究仍然有待进一步深入开展. 相似文献
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为研究反应物当量比对旋转爆震波传播过程的影响,在圆盘形旋转爆震发动机上进行H2/air的旋转爆震实验研究,并统计分析了当量比对爆震波传播模态及参数的影响规律.实验结果表明,固定质量流率,同一种传播模态下,随着当量比的增大,爆震波的压力峰值及传播速度增大,且旋转爆震波的传播过程更加稳定.不同质量流率条件下,当量比对传播模态的影响规律不同.空气质量流率小于100 g/s时,旋转爆震波皆以单波模态传播.空气质量流率大于150 g/s时,随着当量比的增大,旋转爆震波的传播模态由单波模态向双波模态转变,再转变为不对称双波模态,最后又回到单波模态.并且在不对称双波模态中发现了低频振荡现象,振荡频率约为300 Hz.质量流率继续增大,燃烧室中发现了同向三波传播模态.随着质量流率的增加,双波模态的当量比下限降低,不对称双波模态的当量比上限增大,而双波与不对称双波模态的分界线受质量流率的影响较小. 相似文献
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吸气式旋转爆震发动机中燃料的良好雾化对爆震燃烧的组织极其重要,气-液组合横向射流是其中一种重要的燃料喷注技术。为获取气体种类在超声速来流中对其的影响,通过数值方法对液体射流穿透深度和辅助射流气体分布进行研究。采用Euler-Lagrange方法研究不同气体射流对液体射流的作用规律,结果表明:气体射流通过激波结构降低局部来流动量通量提升液体射流穿透深度,相同的来流条件下气体射流动量通量越大,液体射流穿透深度越高,且主要影响扩张段之前的流场区域,气体种类的变化对于后场液体射流穿透深度和雾化特性几乎无影响。 相似文献
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P.S. Tide 《Applied Acoustics》2010,71(3):201-220
Experimental investigations have been carried out on chevron nozzles to assess the importance of chevron parameters such as the number of chevrons (chevron count) and chevron penetration. Acoustic measurements such as overall sound pressure level, spectra, directivity, acoustic power, and broadband shock noise have been made over a range of nozzle pressure ratio from sub-critical to underexpansion levels. Shadowgraph images of the shock-cell structure of jets from various chevron nozzles have also been captured for different nozzle pressure ratios. The results indicate that a higher chevron count with a lower level of penetration yields the maximum noise suppression for low and medium nozzle pressure ratios. Of all the geometries studied, chevron nozzle with eight lobes and 0° penetration angle gives the maximum noise reduction. Chevron nozzles are found to be free from screech unlike regular nozzles. Acoustic power index has been calculated to quantitatively evaluate the performance of the various chevron nozzles. Chevron count is the pertinent parameter for noise reduction at low nozzle pressure ratios, whereas at high nozzle pressure ratios, chevron penetration is crucial. The results illustrate that by careful selection of chevron parameters substantial noise reduction can be achieved. 相似文献
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In this paper, the buoyancy-controlled jet flames from the inclined rectangular nozzles with different aspect ratios have been investigated. The length-to-width aspect ratios of nozzles are 1, 2.25, 4, 9, and 16 with the same cross-sectional area. The inclined angles of the nozzle to the horizontal direction are 0°, 30°, 60°, and 90°. The value of flame length changes at the same inclined angle for different aspect ratios. A correlation has been developed to calculate the flame length of jet flame for different inclined nozzle and aspect ratios with an arbitrary angle. 相似文献
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The present study investigates the effects of the orifice nozzle number and the inlet pressure experimentally on the cooling performance of the counter flow-type vortex tube. The energy generation has been conducted using a stream-tek generator (model GNMD-KIT) with different numbers of nozzles (2, 3, and 6), an aspect ratio of 1:6, and an inner diameter of 7.5 mm. In the experiments, for each of the orifices, inlet pressures have been adjusted from 200–600 kPa. The energy separation investigated here focuses on the cold temperature difference and coefficient of performance for cooling. The experimental results concluded in this article prove that the greatest effect of nozzle number is for three nozzles, and hence, that nozzle number could affect the energy separation efficiently. A comparison of the present experiments with other published works has been conducted. An analytical study of the characteristics equation has been carried out to evaluate the best correlation of the ratio of cold temperature difference to the inlet temperature as a function of pressure, cold mass fraction, and nozzle number. 相似文献
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The mixing fields within a SCRAM-jet combustion chamber are visualized using pressuresensitive paint (PSP) as an oxygen sensor.
The experiments are performed in a small supersonic wind tunnel at the National Aerospace Laboratory — Kakuda Research Center
(NAL-KRC). The main stream Mach number is 2.4, and the dynamic pressure ratios between the injected gas and the main flow
are 0.3, 0.7, 1.1 and 1.5. Three fuel injection nozzles are used; oxygen is injected from the central nozzle and air from
the two nozzles at either side. The spread of the injected gas is measured to observe the effects of placing the nozzles in
different positions. The results show that the jet has its own independent flow structure, and that little mixing of gases
occurs between the flow structures created by each nozzle. When the injection dynamic pressure ratio is increased, the oxygen
fraction rises in the recirculation zone and falls in the separation zone downstream of the injection. 相似文献
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撞击流中颗粒碰撞传热理论模型研究 总被引:1,自引:0,他引:1
建立了考虑颗粒接触面导热的颗粒碰撞传热模型,相应完善了气固两相撞击流理论模型,并对不同条件的撞击流干燥过程进行了模拟。计算结果与实验结果非常吻合,从而验证了所建模型的正确性。本文还分析了颗粒碰撞传热、加料方式以及喷嘴间距对撞击流干燥性能的影响规律。结果表明:在本文所涉及的撞击流干燥过程中,颗粒碰撞传热对干燥性能的影响并不明显;单边加料时颗粒物料的降水幅度及撞击流装置的干燥强度都明显大于双边加料的工况;喷嘴间距较大时,物料的降水幅度及装置的干燥强度均较大。 相似文献
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Serbetci I. Nagamatsu H.T. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(1):91-101
An experimental investigation of the steady-state low current air arcs in a dual-flow nozzle system is presented. The cold flow field with no arc was determined for various nozzle geometries, i.e. two- and three-dimensional and orifice nozzles, and nozzle pressure ratios. Supersonic flow separation and oblique and detached shock waves were observed in the flow field. Using a finite-element computer program, the Mach number contours were determined in the flow field for various nozzle-gap spacings and pressure ratios. In addition, the DC arc voltage and current measurements were made for an electrode gap spacing of ≈5.5 cm and current levels of I ≈25, 50, and 100 A for the three nozzle geometries. The arc voltage and arc power increased rapidly as the flow speed increased from zero to sonic velocity at the nozzle throat. The shock waves in the converging-diverging nozzles resulted in a decrease in the overall resistance by about 15% 相似文献