连续旋转爆震波传播机理、工作特性及其在推进中的应用研究

发布时间：2018-03-08 23:13

  本文选题：爆震近极限传播　切入点：受扰再起爆　出处：《国防科学技术大学》2015年博士论文　论文类型：学位论文

【摘要】：本文设计了连续旋转爆震模型发动机及推力测量系统,通过实验研究与数值模拟相结合的方法,以H_2/air、H_2/O_2和CH_4/O_2为工质,开展了连续旋转爆震波传播机理、工作特性及其在推进中的应用研究。为深入分析连续旋转爆震在约束构型中的波形结构和传播特性,首先在带有管壁约束的爆震管内开展了爆震波近极限传播研究以及爆震波再起爆和受扰传播的研究。发现管长影响爆震极限的准确性,应当在超过初始条件影响长度的长管内开展极限研究。速度亏损和最大速度波动在压力逼近起爆极限时突然增长,不稳定机制在传播中的作用逐渐显著;采用交错多孔板来熄灭或者干扰爆震波的传播,当初始压力高于临界压力时,“稳定”混合气中的爆震起始仅发生在多孔板所能影响到的下游数倍管径距离内。而“不稳定”混合气中的爆震起始不但可以发生在多孔板下游的近场,也能在数十倍管径的远场处以DDT方式从局部爆炸中产生;保持大致相当的堵塞比,增大孔径到一定程度时,多孔板对爆震波传播的扰动作用缩短了不稳定传播模态的传播距离,提供了一种尽快排除不稳定传播模态的方法。针对连续旋转爆震波传播机理这一基础问题,首次将旋转爆震传播模式划分为同向传播模式、双波对撞模式、低速爆震模式和不稳定传播模式,并分析了各自形成机制。发现燃烧室压力与出口背压之比是影响爆震波稳定性的重要因素。在基准构型的模型发动机中,保持当量比恒定,随着流量增大,燃烧室内依次经历不起爆—低速爆震模式—不稳定爆震模式—同向传播模式的演变,而同向模式依次出现单波模态—单/双波混合模态—双波(多波)模态。产生低速爆震模式和不稳定爆震模式是由于燃烧室压力与出口背压之比比较低,出口处旋转斜激波后的区域产生斜激波并被推到燃烧室内比较靠上的位置干扰喷注,引起传播不稳定。对于同向传播模式,燃烧室出口排气为超声速,背压对燃烧室内无影响。此外,在一些特殊构型中(比如0.2 mm宽空气喷注喉部)或以N2吹除时,燃烧室内可能出现双波对撞模式,此时能够尽快建立混合层成为维持对撞的关键。结合实验和数值模拟结果,深入分析了燃烧室流道长度、流道厚度、流道曲率以及轴向出口收缩等构型约束对H_2/air连续旋转爆震波流场结构、传播过程及推力性能的影响规律。研究表明上述构型约束对于旋转爆震波流场结构(爆震波高度、波前压力、稳定性)、流场参数、流量、推力和比冲等存在不同程度的影响。分析表明:维持连续旋转爆震波传播所需流道长度存在最优值,且流道曲率存在上限。在空桶燃烧室内实现并开展了以CH_4/O_2和H_2/air为工质的旋转爆震研究。观测了CH_4/O_2旋转爆震的传播过程及流场结构。对于H_2/air工质来说,流量增大导致爆震波传播速度和峰值压力均增大,燃烧室内发生了模态转变,依次出现双波对撞模态—双波模态—单波模态,前两个模态受到了出口产物中所产生的上行斜激波的影响。研究表明环形通道不是维持旋转爆震的必要条件,而喷注充足的可燃混合物是维持稳定旋转爆震的关键。在目前流量下,空桶内的旋转爆震产生的推力性能不高。针对连续旋转爆震燃烧在推进中的应用,实现了旋转爆震模型发动机的推力测量,讨论了典型模态下的推力性能及推力稳定性。实验表明:连续旋转爆震波能够长时间稳定工作,在模型发动机中产生稳定、可靠的推力。爆震波头个数增多有助于推力稳定。推力波形的振荡频率与爆震波高频压力波形存在耦合关系;随着流量的增大,爆震波传播模态及稳定性发生改变,推力增长,比冲增大并趋于稳定;当量比对爆震波传播模态、传播速度和推力性能均会产生影响;流量、推力和燃烧室压力随喷注压力增大而快速增长。此外。随着喷注面积的增大,需要更大流量和更高喷注压力才能建立起维持单波头旋转的条件。针对旋转爆震波较强的流量适应能力,系统分析了连续旋转爆震发动机的矢量调节技术,论证了矢量调节的可行性。发现存在两种矢量调节模式:模式I—一个周期内出现两次推力偏转,旋转爆震发动机以两倍的爆震波旋转频率进行矢量调节。模式II—旋转爆震发动机一直保持向低压喷注区方向的偏转;面向火箭基旋转爆震发动机的应用,分析了活性较高的H_2/O_2和CH_4/O_2混合气中旋转爆震波的工作特性和推力特性。因为诸多原因限制,H_2/O_2混合气所产生的比冲指标与理论性能尚有较大差距;CH_4/O_2混合气中的旋转爆震比较平稳,但N2稀释的比例对混合气的旋转爆震特性影响比较大。随着总流量的增大,总比冲性能有所提升。
[Abstract]:This paper designed a continuous rotating detonation model and engine thrust measurement system and method, through the combination of experimental research and numerical simulation on H_2/air, H_2/O_2 and CH_4/O_2 as refrigerant, the continuous rotating detonation wave propagation mechanism, characteristics and application in the research work in advance. For in-depth analysis of continuous rotating detonation in the configuration constraints the structure and wave propagation characteristics in the first with a tube wall constraint detonation tube was carried out to study wave propagation in detonation and detonation and limit of disturbance propagation of detonation wave was renewed. Accuracy of the knocking limit length effect, should be in excess of the influence of initial conditions of long tube length is carried out within the limit of the maximum speed and speed loss. Fluctuation limit sudden growth in the approximation of detonation pressure, instability mechanism in spreading gradually significantly; a staggered perforated plate to knock out or interference Wave propagation, when the initial pressure is higher than the critical pressure, the detonation initiation stability in gas mixture occurs only can affect downstream of the perforated plate in the diameter range. Several times and "unstable detonation initiation" in the mixed gas can not only occur in the near field downstream of the perforated plate, but also in dozens of times the diameter of the far field a DDT generated from the local explosion; remain roughly the same blockage ratio, aperture increases to a certain extent, the porous plate shortens the propagation distance of unstable propagation mode disturbance effect on detonation wave propagation, and provides a method for removing as soon as possible unstable propagation modes on the basic. The problem of continuous rotation of the propagation mechanism of detonation wave, the rotating detonation propagation mode is divided into the same mode of transmission, double wave collision model, low detonation mode and unstable propagation mode, and analyzes their formation mechanism. It is found that burning The important factors of combustion chamber pressure and outlet pressure ratio is the impact of detonation stability. In the benchmark model of engine configuration, keep the equivalence ratio constant, as the flow increases, followed by experience - low - detonation detonation mode unstable detonation mode evolution and propagation mode to the combustion chamber, and in the same direction in single mode wave modes - Single / double wave mixed mode double wave (wave) mode. Low detonation mode and unstable detonation mode is due to the combustion chamber pressure and outlet pressure ratio is relatively low, at the outlet of the swash post shock region produced shock and pushed into the combustion on the comparison of injection position disturbance the interior, causing the spread of instability. For the same propagation mode, the combustion chamber exhaust is supersonic, pressure has no effect on the combustion chamber. In addition, in some special configurations (such as 0.2 mm wide air injection throat) or to N2 Purge, the combustion chamber may appear double wave collision model, this can become the key to maintain the mixed layer as soon as possible to establish the collision. The simulation results combined with experimental and numerical analyses of combustion chamber flow channel length, channel thickness, channel curvature and axial contraction of export configuration constraints on H_2/air continuous rotating detonation wave flow structure, influence of process and the thrust performance of communication. Research shows that the configuration constraints for rotating detonation wave flow structure (detonation wave height, wave pressure, stability), flow field parameters, flow, thrust and impulse the existence of different effects. The analysis shows that: the maintenance of continuous rotating detonation wave required channel length and the flow channel exists optimal value. In the presence of upper curvature. The empty barrel combustion chamber to realize and carry out the research of rotating detonation working with CH_4/O_2 and H_2/air. CH_4/O_2 was observed in the rotating detonation propagation process of shock And the flow structure for H_2/air refrigerant flow, increase of detonation wave speed and the peak pressure increased, the mode transformation, the combustion chamber, there are two wave impinging wave modes - Single - mode double wave mode, the first two modes are affected by the upward oblique shock wave produced in the product export. Research shows that the annular channel is not necessary to sustain rotation of the detonation, and the combustible mixture injection is the key to maintain a stable enough. In the current rotating detonation flow, rotating detonation empty bucket generated thrust performance is not high. Aiming at continuous rotating detonation combustion application in advance, the thrust measurement of rotating detonation model the engine thrust and thrust performance, discusses the stability of typical modes. The experimental results show that the continuous rotating detonation wave can work stably for a long time, in the model of the engine to generate stable, reliable Thrust head number increased. The detonation wave contributes to thrust stability. The coupling relationship between the oscillation frequency of the thrust waveform and the detonation wave high frequency pressure wave; along with the increase of flow rate, detonation propagation mode and stability of shock wave change, thrust growth, specific impulse increases and tends to be stable; equivalence ratio of detonation wave propagation velocity and thrust mode. The performance will influence; flow, thrust and combustion chamber pressure with the injection pressure increases. With the increase of rapid growth. In addition the injection area, the need for greater flow and higher spray injection pressure to maintain the established single wave head rotation condition. According to the rotating detonation wave strong flow ability, system analysis continuous vector rotating detonation engine control technology, demonstrates the feasibility of vector control. It is found that there are two kinds of vector control mode: I - a period of two times the thrust deflection, rotating detonation Shock engine vector control based on two times the detonation wave. The rotation frequency of II rotating detonation engine has been maintained to the low pressure jet deflection direction; the application of rocket based rotating detonation engine, analyzes the working characteristics and thrust characteristics of high activity of H_2/O_2 and CH_4/O_2 mixed gas in the rotating detonation wave because of many reasons. Limit of H_2/O_2 mixed gas generated by the specific impulse and the theoretical performance indexes have a large gap; rotating detonation CH_4/O_2 gas mixture are relatively stable, but the effects of N2 dilution ratio on rotating detonation characteristics of mixed gas is relatively large. With the increase of the total flow, the total specific impulse performance has improved.

【学位授予单位】：国防科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：V430
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本文编号：1585962