固体火箭发动机地面和飞行过程中羽流红外辐射的计算研究

Study on Plume Infrared Radiation of Solid Rocket in Ground Test and Flight Condition

为研究固体火箭发动机地面和高空飞行过程中羽流红外辐射随飞行高度的变化,计算了某型固体火箭发动机在地面试车和7.5-80 km之间一系列高度工况下,发动机内、外流场和红外波段2--6μm的辐射。发动机内流和羽流流场采用非平衡化学冻结模型计算,高温Al2O3颗粒和燃气组分混合的羽流辐射场采用FVM模型计算,其中燃气组分的光谱特性用WSGG模型计算,Al2O3颗粒的光谱特性用Mie理论计算。研究了2.7-2.95μm、3.6--3.85μm和4.2-4.45μm三个波段,羽流高温核心区表面的辐射强度;以及高温核心区在轴向主平面和法平面上,0°、45°和90°三个视角的辐射亮度。研究发现：随飞行高度上升,环境压力下降,羽流体积膨胀,其中高温核心区气相温度迅速下降,Al2O3颗粒浓度也所有下降,但颗粒温度仍比较高。发动机在地面工作时,羽流的强辐射带沿其轴线呈连续状分布;但在高度小于22.5 km的低空飞行时,羽流的强辐射带除了出口区域以外,还在出口下游的后燃区出现。羽流的红外辐射亮度在纵截面上具有轴对称性。在光谱分布方面,发动机飞行高度小于40 km时,羽流辐射呈现燃气辐射的光谱差异性,但发动机在40 km高度以上飞行时,羽流辐射呈现高温颗粒辐射的光谱连续性。

For purpose of study the infrared radiation of solid rocket plume in ground test and its variation with altitudes in flying condition, the internal flow and plume flow, and plume radiation in infrared waveband 2-6um, in ground test and a series of flying altitudes between 7.5-80 km, were taken for investigation in this work. The internal flow and plume flow were computed with non-equilibrum chemical frozen model. The spectral directed radiance of the nonuniform absorptive/emmissive/scattering plume in the 2-6um infrared waveband was computed with the FVM methods, while the spectrum characteristic of gaseous compositions and Al2O3 particles were solved by WSGG model and Mie theory, respectively. Radiation of the high temperature core in the plume was studied, of which intensity on the outer surface of high temperature core in three wavebands, 2.7-2.95um, 3.6-3.85um and 4.2-4.45um, and its radiance from the axial plane and normal plane in three view angles, 0°, 45° and 90°, were studied in detail. One important characteristics of plume flow was that the plume volume would expanded extensively with sharp decrease of external pressure when the flying altitudes got up and both the gas temperature and Al2O3 particles concentration dropped down raplidly in that process, but the particles temperature were still very high. The infrared radiation of rocket plume showed three characteristics from our study. The first one was that the strong radiation zone for rocket motor in ground test lied along the axis which was continous, but there were two seperated strong radiation zones for low altitudes less than 22.5 kin, one is near the outlet, the other is in the afterburning zone. For higher altitude plumes, only outlet zone had a strong radiation. The second characteristic was that plume radiation was axial symmetrical in the normal plane, while not symmetric in the axial cross plane. The third characteristic was about the spectral property, which showed gases spectral difference for altitudes below 40 km, but showed spectral continuity of A1203 particle radiation for higher altitudes.