适用于不同高度的等离子体体积力唯像学模型

针对等离子体流动控制数值模拟中唯像学模型高度适应能力不足的问题，假设等离子体中离子数密度正比于放电光强，对101.3~1.5kPa气压下等离子体放电图片进行灰度处理，得到等离子体发光的相对光强、光强比即离子数密度随气压、激励电压的变化特点。结果表明:随着气压增大，从弥散放电逐渐转化为丝状放电，而光强比逐渐减小，可以使用大气压下的饱和总相对光强代替其他气压下的结果；提高激励电压，等离子体出现双侧放电，且放电光强增大，放电电荷与激励电压近似成线性关系。进一步通过理论推导建立了新的电荷分布边界条件，并拟合了多个气压和激励电压下等离子体发光的相对光强，然后选择其中两个典型工况进行数值模拟，将计算结果与相应气压下等离子体诱导射流激光粒子图像测量结果进行比较，对该模型进行了验证，表明该模型能够准确模拟飞行高度、激励电压对等离子体诱导射流的影响。 

Plasma body force phenomenological model for different altitudes

In order to use the plasma body force phenomenological model to simulate the plasma flow control at different altitudes, if assuming the ion number density was directly proportional to plasma light emission, the relative light intensities of plasma emission and light intensity ratios i.e. ion number densities with gas pressure and applied voltage, were obtained by processing the plasma discharge image to gray scale at varying pressures 101.3-1.5kPa. It was found that when the pressure increased, the discharge became filamentary from diffuse, while the light intensity ratios decreased. The saturated relative light intensity in the atmospheric pressure can be used to represent one in other pressures. When the applied voltage increased, discharge occurred at the double-sides of actuator, and the light intensity increased. The total discharge had a linear relationship with applied voltage. Then the new charges boundary condition was built by theory analysis, and the relative light intensities of several plasma emissions at different gas pressure and applied voltage were fitted. Two typical cases were simulated, and the results were used to compare with the plasma jets at corresponding gas pressures measured by particle image velocimetry. It is shown that the new model can simulate the influences on the plasma jets by flight altitude and applied voltage.