受限空间内双向涡流雷诺应力方向性特性研究

发布时间：2017-12-31 07:11

本文关键词：受限空间内双向涡流雷诺应力方向性特性研究　出处：《哈尔滨工程大学》2016年博士论文　论文类型：学位论文

【摘要】：诞生于21世纪的涡流冷壁推力室概念(Vortex Combustion Cold-Wall Chamber,VCCWC)是涡流技术工程化应用的典型代表,该推力技术的核心内容为限制在推力室范围内、具有特殊速度分布形式的涡流,该涡流存在轴向速度反向,在推力室壁面与燃烧反应区之间形成外涡冷流,该外涡冷流对推力室壁面起到了隔离热量传递、吸收热量传递的双重作用。本文采用数值计算与理论推导相结合的研究方法,对VCCWC内的核心流动:双向涡流进行系统深入的研究,以理论模型结果与实验结果为参考,揭示受限空间内双向涡流流动及其雷诺应力特征,进而提出其外涡冷流所具有的隔离、吸收热量传递的双重作用。以实验数据和解析模型作为参考,以RSM模型计算结果作为对照,研究了基于各向同性涡粘性假设湍流模型中的旋转修正方法在双向涡流数值计算中的适用性。三种旋转修正方法中,附加旋转修正方法性能最差,附加旋转修正项对双向涡流几乎没有作用。漩涡修正方法在修正因子取默认值0.07时也没有太大改善。曲率修正方法在切向速度预测上相较于前两种方法有了非常显著的改善,但是在轴向速度分布预测上,曲率修正方法依然无法反映出双向涡流最本质特征:壁面附近的轴向速度反向。通过三种旋转修正方法与实验及理论解的比较可知,只有切向速度分布与轴向速度分布同时符合双向涡流理论,才能确认双向涡流数值计算结果的正确性。从Boussinesq各向同性假设出发,以实验数据和理论模型作为参考,研究了双向涡流雷诺应力方向性特征。根据计算结果可知,二次压力-应变RSM模型在预测双向涡流方面存在一定优势,其准确程度较线性RSM模型有了一定提高。双向涡流场雷诺应力随涡雷诺数增大而增大,雷诺应力方向性均显著,在径向雷诺应力峰值的无量纲半径位置处,径向雷诺应力与切向雷诺应力差距达到了切向雷诺应力的150%左右。RNG模型所得雷诺应力与RSM模型存在较大差别,各向同性假设使得RNG模型所得雷诺应力趋于均匀。雷诺应力预测错误最严重的是切向雷诺应力,其分布趋势与两种RSM模型相去甚远。径向雷诺应力与轴向雷诺应力虽然给出了正确的雷诺应力分布趋势,但是数值大小上与准确值相去甚远。未来对涡粘性湍流模型进行考虑双向涡流特征的修正时,需要人为引入雷诺应力方向性特征。以实际涡流冷壁推力室中的收敛喷管为研究对象,数值模拟研究了收敛段入口尺寸所形成的肩径比对推力室内压力场及速度场的影响。肩径比远大于无量纲涡幔半径时,收敛段入口处与肩部涡之间形成的出口涡破坏了流动的顺畅性,大的肩径比通常无法达到推力室喷管的收缩比要求。肩径比与无量纲涡幔半径相当时,形成与理论模型非常接近的理想双向涡流,此时推力室效率达到最高。当肩径比小于无量纲涡幔半径时,收敛段内会形成虚拟收敛段,该虚拟收敛段不依赖于肩径比,入射口氧化剂来流中的一部分会直接从喷管流出而并不参加内涡燃烧反应,因而推力室效率显著降低。旋流条件与双向涡流特性耦合研究中,通过数值计算发现,切向速度及最大切向速度均随入射倾角的增大而减小,随入射压降增大而增大,随长径比的增大而减小。不同入射倾角、不同入射压降、不同长径比下整个发动机内最大切向速度的无量纲径向位置均恒定在0.19附近。对于不同长径比工况,长径比为1.0时,最大切向速度从发动机顶端到入射口附近逐渐增大,长径比为1.5时,最大切向速度从发动机顶端到入射口附近先增大后减小。切向速度及最大切向速度的轴向衰减率维持在3%以内。无量纲涡幔半径从发动机顶端开始线性增大到入射口附近,变化范围为0.71至0.82。入射倾角相同时,随入射压降的增大燃烧室长径比对最大切向速度大小的影响将随之增大通过理论推导方法,对涡流冷壁推力室内的传热过程进行了理论分析与建模过程,建立了热流量平衡关系式。通过理论分析指出,外涡氧化剂冷流存在两个作用:外涡氧化剂冷流的存在,导致内涡向壁面传热的热阻增大了 14倍以上;由于所吸收的一部分热量用于自身温度的升高,外涡氧化剂冷流对壁面事实上起到了冷却作用,导致外涡向壁面的传热量只占内涡总传热量的60%以下,因此可知外涡氧化剂冷流起到了阻碍热量传播与冷却推力室壁面的双重作用。
[Abstract]:Born in twenty-first Century in the vortex wall of thrust chamber (Vortex Combustion Cold-Wall Chamber concept, VCCWC) is a typical application of eddy current technology engineering, its core technology is limited in the thrust thrust chamber with special speed range, eddy current distribution form, the vortex flow axial velocity between the reverse thrust chamber wall with the combustion reaction zone is formed outside the outer vortex flow of cold vortex, cold flow on the thrust chamber wall to isolate heat transfer, heat transfer double effect absorption. Research in this paper by means of numerical calculation and theoretical derivation combining the core flow in VCCWC: systematic research on bidirectional eddy current, in theory the model results with the experimental results for reference, revealed in limited space and two-way eddy flow Reynolds stress characteristics, and then puts forward the outer vortex isolation cold flow has the dual role of heat absorption. Based on the experiment data and the analytical model as a reference to the RSM model calculation results as control, study the applicability of rotation correction method of isotropic eddy viscosity turbulence model based on the assumption in the two-way eddy current in numerical calculation. Three rotation correction method, additional rotation correction method for the poor performance, the additional rotation correction of bidirectional eddy current almost no effect. The vortex correction method the default value of 0.07 is not much improvement in the correction factor. The curvature correction method in tangential velocity prediction compared to the previous two methods have a very significant improvement, but the axial velocity distribution prediction, curvature correction method still can not reflect the essential characteristics of two-way eddy current: the axial velocity near the wall. By comparing three kinds of reverse rotation correction method and experimental and theoretical solution, only the distribution of tangential velocity and axial velocity distribution at the same time. The theory of double vortex, in order to confirm the correctness of the two-way eddy current numerical computation. Starting from the Boussinesq isotropic hypothesis, based on the experiment data and theoretical model as reference, the two-way vortex Reynolds stress direction characteristics. According to the results, the two pressure strain RSM model has certain advantages in predicting bidirectional eddy current. The degree of accuracy than the linear RSM model has been improved. The bidirectional eddy current field Reynolds stress increases with the increase of vortex Reynolds number, Reynolds stress direction significantly, should the dimensionless radius position of peak force in radial Reynolds, radial Reynolds stress and tangential Reynolds stress gap reached tangential velocity the 150%.RNG model of income difference should be Reynolds stress and RSM model, the isotropic hypothesis makes the RNG model obtained from the Reynolds stress uniformly. The Reynolds stress prediction error is the most serious Tangential Reynolds stress, the distribution trend and two kinds of RSM models far. Radial Reynolds stress and axial Reynolds stress although given the correct Reynolds stress distribution trend, but the magnitude and exact value far. The future of eddy viscosity turbulence model considering vortex flow characteristics of the bidirectional correction, need to be artificially introduced Reynolds stress direction characteristics. The convergent nozzle wall in actual vortex thrust chamber as the research object, numerical simulation of the entrance convergent section the size of shoulder radius on the thrust chamber pressure field and velocity field. The shoulder diameter ratio is far greater than the dimensionless radius of mantle vortex, the vortex formed between the convergent section the entrance and shoulder vortex destroyed smooth flow, large shoulder diameter ratio cannot achieve the nozzle contraction ratio. The shoulder diameter ratio and dimensionless mantle vortex radius, formation and theoretical model Very close to the ideal two-way vortex, the thrust chamber efficiency reaches the maximum. When the shoulder diameter is less than the dimensionless radius of vortex mantle, will form a virtual convergent section convergence period, the virtual convergent section does not depend on the shoulder diameter ratio, inlet oxidant flow in part will flow directly from the nozzle and does not take part in the in the vortex combustion reaction, so the thrust chamber efficiency is significantly reduced. The coupling study of swirl conditions and bidirectional swirl characteristics, through numerical calculation, the tangential velocity and the maximum tangential velocity increase with incident angle decreases with the increasing incidence of pressure drop increases, decreases with the increase of slenderness ratio for different incident angles. Different incident, pressure drop, different length diameter ratio of the engine maximum tangential velocity and dimensionless radial position are constant in the vicinity of 0.19. For different aspect ratio condition, when the slenderness ratio is 1, the maximum tangential velocity from the top of the engine To the incident near the mouth gradually increased when the slenderness ratio is 1.5, the maximum tangential velocity from the engine to the top of the incident near the mouth increases first and then decreases. The tangential velocity and axial velocity to the maximum shear attenuation rate remained at less than 3%. The dimensionless radius of vortex mantle from the engine began to increase linearly with the top incident near the mouth, change in the range of 0.71 to 0.82. incident angle at the same pressure drop with increase of incident combustion long diameter ratio of the maximum tangential velocity will increase with the size of influence through theoretical derivation method, the heat transfer process of vortex wall thrust chamber is analyzed and the modeling process, established the thermal flow equation. Through theoretical analysis, pointed out that the outer vortex oxidant cold flow has two effects: there is the outer vortex oxidant cold flow resistance, heat transfer within the vortex wall leads to increase of 14 times; due to the absorption of some heat for themselves The increase of temperature, the outer vortex oxidant cold flow on the wall in fact play a cooling effect, resulting in the outer vortex wall surface heat transfer only within the vortex of the total heat transfer of less than 60%, so that the outer vortex oxidant cold flow which prevent the heat transmission and cooling thrust chamber wall surface of the dual role.

【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O35

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