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为研究超声速气流中简化液滴的汽化过程问题,本文分析了两相流计算中已有的两相传热模型,并对简化液滴绕流开展数值计算。在来流Ma 0.6的条件下,数值计算得到的简化液滴-气流之间的传热速率与已有模型得到的结果相一致,而在来流Ma 0.9的条件下,数值计算得到的简化液滴-气流之间的传热速率与已有模型得到的结果存在很大偏差。由此建立了考虑简化液滴与气流相对超声速相互作用的两相传热模型。进一步,采用Charles B.Henderson阻力系数关系式与新建立的传热模型,对不同直径简化液滴的运动与汽化开展工程计算。在来流2.7Ma的二维平板超声速流场中选取一个截面,作为气相流场,结果显示,(1)简化液滴与主气流存在相对超声速作用,当简化液滴直径dk 0.12mm时,作用区域约为0.1m～0.4m,当dk>0.12mm时,作用区域明显增大,(2)简化液滴的穿透尺度不超过0.011m/m(深度/长度),时间尺度约为0.28ms～3ms,(3)简化液滴完成汽化的空间尺度约为0.1m(dk=0.03mm)、0.45m(dk=0.05mm)与1.24m(dk=0.075mm),而当dk>0.09mm时,简化液滴完成汽化的空间尺度则大于1.9m。使用考虑简化液滴与气流相对超声速相互作用的两相传热模型与使用传统的传热模型对简化液滴的运动轨迹没有影响,而对简化液滴的汽化过程有较大影响。
In order to study the vaporization process of simplified droplets in supersonic gas flow, the existing two-phase heat transfer model in the calculation of two-phase flow is analyzed in this paper, and the numerical calculation of simplified droplet flow is carried out. Under the condition of Ma 0.6, the simplified heat transfer rate between the simplified droplet and the gas flow is consistent with that obtained by the existing model. Under the condition of the flow Ma 0.9, the calculated simplified liquid The rate of heat transfer between the droplet and the gas stream deviates greatly from the results obtained with the existing models. Thus, a two-phase heat transfer model considering the relative supersonic interaction between drop and gas flow is established. Further, using Charles B. Henderson resistance coefficient and the newly established heat transfer model, engineering calculations were performed on the movement and vaporization of droplets with different diameters. The results show that (1) there is a relative supersonic effect between the droplet and the main gas stream, and the effect of the simplified droplet diameter dk 0.12mm The area is about 0.1m ~ 0.4m. When dk> 0.12mm, the area of action increases obviously. (2) The simplified drop penetration does not exceed 0.011m / m (depth / length) and the time scale is about 0.28ms ~ 3 ms. (3) The simplified spatial scale for the completion of vaporization of droplets is approximately 0.1 m (dk = 0.03 mm), 0.45 m (dk = 0.05 mm) and 1.24 m (dk = 0.075 mm) , To simplify the completion of the vaporization of the droplets space scale is greater than 1.9m. The use of a two-phase heat transfer model that takes into account the relative supersonic interaction of the droplet and the gas stream has no effect on simplifying the trajectory of the droplet using a conventional heat transfer model, but has a greater impact on simplifying the vaporization of the droplet.