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为得到当量比对航空发动机防火试验温度分布的影响,建立了NexGen燃烧器的数值计算模型,使用Fluent计算了7组当量比的火焰温度分布。燃烧模型采用非预混燃烧模型与20组分单煤油分子C_(12)H_(23)的概率密度函数方法。使用雷诺时均模型与SST k-ω湍流模型求解火焰的湍流方程。使用离散坐标辐射模型和灰体加权平均模型的求解火焰的辐射。液体燃料液滴根据离散随机游走模型与湍流气体介质的相互作用建立模型。分析了7组当量比对防火试验火焰温度的点分布、面分布和空间分布的影响。得到随当量比的增加,Z轴最高温度位置先变大后减小;监测点的平均温度先升高后降低;监测面的最高温度先降低后变化平缓再增加,与浴盆曲线相近;监测面的平均温度先降低后平缓再增加。当量比小于1时,各平面的平均温度随当量比增加而降低;当量比大于1时则升高。当量比为0.9时,火焰空间温度分布最好、各平面的温度分布最均匀、监测面的温度分布最均匀、七个监测点的温度值及分布适中。
In order to obtain the effect of equivalence ratio on the temperature distribution of aeroengine fire test, a numerical calculation model of NexGen burner was set up. The flame temperature distribution of seven equivalence ratios was calculated by Fluent. The combustion model uses the probability density function method of non-premixed combustion model and single component kerosene C_ (12) H_ (23). The Turbulence Equation of a Flame Using Reynolds Average Model and SST k-ω Turbulence Model. Solving Flame Radiation Using Discrete Coordinate Radiation Model and Gray Body Weighting Averaging Model. Liquid fuel droplets are modeled by the interaction of the discrete random walk model with the turbulent gas medium. The effects of seven equivalence ratios on the distribution of point temperature, area distribution and spatial distribution of flame temperature in fire test were analyzed. With the increase of equivalence ratio, the position of Z-axis maximum temperature first becomes larger and then decreases. The average temperature of the monitoring point first increases and then decreases. The maximum temperature of the monitoring surface decreases first and then increases gently, which is similar to the curve of the bathtub. The average temperature decreases first and then increases gently. When the equivalence ratio is less than 1, the average temperature of each plane decreases with the equivalence ratio, while the equivalence ratio is greater than 1. When the equivalence ratio is 0.9, the temperature distribution in the flame space is the best, and the temperature distribution in each plane is the most uniform. The temperature distribution in the monitoring surface is the most uniform, and the temperature value and distribution in the seven monitoring points are moderate.