湍流脉动对圆射流红外辐射特性的影响研究

为研究湍流脉动对高温燃气圆射流红外辐射强度的影响，利用大涡模拟方法计算了高温圆射流流场的温度和组分浓度等的瞬时值和平均值，在此基础上分别采用平均温度?辐射法和瞬时温度?辐射法计算了射流场的红外辐射特性。计算结果表明:瞬时温度?辐射法计算的平均光谱辐射强度、平均积分辐射强度和平均辐射亮度均高于平均温度?辐射法计算的结果；湍流脉动越大，掺混区越厚，两种方法的计算结果之间的差值以及射流场红外辐射的脉动幅值均越大，其中射流高温核心区尾缘附近是受湍流影响最强的区域；两种方法计算的平均红外辐射亮度之间的差值沿着径向逐渐降低。对于Re=86 000，环境温度与进口温度之比为0.35的圆射流，在90°探测方向上，瞬时温度?辐射法计算的总的平均积分辐射强度比平均温度?辐射法的计算结果高23.6%左右。

Influence of turbulent fluctuations on the infrared radiation characteristics of round jet flow

To investigate the influence of turbulent fluctuation on the infrared radiation (IR) characteristics of high-temperature round gas jet flow, the instantaneous and time-averaged values of temperature and species concentration of a high temperature round jet flow was calculated using the Large Eddy Simulation, and then the IR characteristics of the jet flow was calculated by two methods: one was based on mean temperature and another was on instantaneous temperature. The results show that the time-averaged values of the spectral IR intensity, the integral IR intensity and the IR brightness calculated by the second method are higher than that calculated by the first method. Both the differences between the results of the two methods and the IR fluctuation increase with the turbulent fluctuation and mixing layer thickness increasing, and the area that is affected the strongest by the turbulent fluctuations is the vicinity of the trailing of the high-temperature core zone in the jet flow. The difference between the IR brightness calculated by the two methods gradually decrease along the radial direction. For the round jet flow at Re=86 000 and the ratio of the temperature of surrounded air and the jet inlet temperature is 0.35, the integral IR intensity at the 90° detection direction calculated by the second method is higher than that calculated by the first method by 23.6%.