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超燃冲压发动机燃烧室液体射流雾化数值模拟   总被引:1,自引:0,他引:1  
为了研究超燃冲压发动机燃烧室中液体射流喷射压力、燃烧室进口总温以及液体物性对射流雾化特性的影响,使用计算流体力学软件对超声速燃烧室中的液体雾化两相流场进行了数值模拟.计算采用欧拉-拉格朗日方法,NG k-ε湍流模型,波致破碎模型.计算结果表明,喷射压力增大,液体射流的穿透深度增加;燃烧室进口总温升高,液体射流的穿透深度减少;表面张力对雾化粒径的影响比动力粘度的影响显著,液体表面张力越大,雾化形成的液滴粒径越大.  相似文献
2.
In this paper we consider size-biased discrete phase-type and matrix-geometric distributions, and we prove that their factorial moment distributions remain within their respective classes. We provide explicit representations of these factorial moment distributions.  相似文献
3.
本文给出一种采用DPT估计SNCK信号时宽—带宽积的方法,并通过仿真该估计方法的性能与其它估计方法进行比较.首先给出SNCK信号参数估计的一般过程.为了便于计算和理论推导,根据估计出的中心频率将接收到的SNCK信号搬移到零频,从而进一步估计其它参数,如采用DPT估计SNCK信号时宽带宽积.本文将重点研究采用DPT算法估计SNCK信号值的方法.  相似文献
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针对某小型航空发动机单级轴流压气机的清洗需求,以数值模拟结合实验的方法对压气机清洗流场的各种参数进行了分析研究.在初步确定清洗方案的基础上,建立了基于S-A湍流模型的离散相数值模拟理论模型,以经验公式估算喷嘴形成的初始液滴分布,并对喷嘴的实验参数进行了校准,最后以CFD软件进行了流场的数值模拟,计算结果表明:清洗液滴不会对压气机的流场产生明显影响,平面扇形喷嘴在该小型压气机上能获得较好的清洗效果.  相似文献
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针对某型发动机的2种不同结构的油气分离器,采用FLUENT对流场进行数值模拟.使用RNG k ε模型计算连续相气体,得到油气分离器内部的流场速度分布.使用离散相模型(Discrete Phase Model,DPM)计算液态油滴,追踪离散项的运动轨迹,从而计算得到分离效率.探讨影响油气分离效率的因素,同时进行试验验证.结果可为油气分离器的后续优化设计提供参考.  相似文献
6.
针对蒸发冷却技术相关理论模型并未完全成熟的问题,通过计算流体力学方法模拟转炉煤气干法除尘系统中蒸发冷却器的工作过程.仿真采用离散相模型(Discrete Phase Model,DPM),并在分散相液滴上应用蒸发换热模型.通过该数值方法优化该干法除尘系统中蒸发冷却器的喷淋布置方案,减少壁面的高温区域,提高温度的均匀性,使出口最高温度偏差由18.6%降低至3.4%.  相似文献
7.
建立试验弯管和节流管汇2个高压管汇实体模型.基于CFD方法,采用离散相模型计算不同半径粒子的轨道和岩屑对高压管壁的冲蚀.计算结果与试验数据较为吻合,能预测节流管汇磨损严重部位,为指导节流管汇的设计和定期检测提供参考.  相似文献
8.
The effect of the cone tip-diameter on the flow field and performance of cyclone separator was investigated computationally and via mathematical models. Three cyclones with different cone tip diameters were studied using large eddy simulation (LES). The cyclone flow field pattern has been simulated and analyzed with the aid of velocity components and static pressure contour plots. In addition the cyclone collection efficiency based on one-way discrete phase modeling has been investigated. The results obtained demonstrate that LES is a suitable approach for modeling the effect of cyclone dimensions on the flow field and performance. The cone tip-diameter has an insignificant effect on the collection efficiency (the cut-off diameter) and the pressure drop. The simulation results agree well with the published experimental results and the mathematical models trend.  相似文献
9.
Discrete systems are used in several fields such as reliability and computing and electronics in digital systems. On the other hand, there are systems that cannot be continuously monitored and they can be observed only at certain periods of time, via inspections, for example. In this paper a repairable multi-component system subject to internal and accidental external failures with loss of units is developed. The system is composed of a finite number of units, including the main one and the others disposed in cold standby. If a repairable failure occurs, the main unit enters the repair channel. On the other hand, the unit is removed if the failure is non-repairable. A repairman is considered. The distribution of the lifetime of the main unit is a general one and its phase-type representation is considered. Accidental failures occur according to a general discrete renewal process. The model is developed in detail and the up period is worked out up to no units and up to total failure of the system. Some reliability measures of interest such as the conditional probability of different types of failures are calculated. The operating of the system is analysed according to rewards introduced in the model. We have built complex algorithms for calculating the measures defined in this paper. We have introduced the RG-factorization method to work out these measures by means of matrices with low order. The results have been implemented computationally with Matlab. An example illustrates the model and the number of units is optimised according to the average net reward.
Rafael Pérez-OcónEmail:
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