影响激波管动态压力校准精度的关键问题研究

发布时间：2018-04-30 15:48

本文选题：激波管 + 动态压力校准精度　；参考：《中北大学》2016年博士论文

【摘要】：动态压力校准技术是保证动态压力测试精度的关键,激波管校准装置在动态压力校准技术中使用最为普遍,世界上许多国家都推荐使用激波管装置进行动态压力校准。因此,对提高激波管装置校准精度的研究具有意义。本文针对影响激波管动态压力校准精度的几项关键问题展开研究,主要采用理论分析、试验验证以及数值仿真分析三种手段进行。主要工作和结论如下：介绍了激波管动态压力校准技术及由此获得压力传感器动态特性的方法。随后介绍了计算动态压力信号幅值的经典Rankine-Hugoniot超压公式的推导过程,对三种导致压力幅值计算产生误差的因素进行了分析,分别是介质比热比K值变化、激波传播的沿程能量损失以及激波后介质的气体状态方程非理想,并得出激波后气体的不理想状态导致的误差最大。选取符合实际情况,包含空气含湿量参数的维里方程计算实际气体状态的压缩因子,将压缩因子代入修正后的超压计算公式,经修正公式计算得到的激波超压值更加接近激波管试验的实测值。试验结果说明计及实际气体状态的超压计算方法是一种有效的尝试。针对激波管的一些关键流场问题,利用有限元方法进行数值模拟研究。以常用的流体力学有限元软件FLUENT作为平台,对管截面形状、破膜开口尺寸、激波沿程衰减和传感器安装不平整几个问题进行仿真研究。管截面形状问题仿真结果为激波管的设计制造提供了参考依据,破膜开口尺寸与激波沿程衰减问题的仿真结果对于激波管试验方案的设置有一定的参考意义,传感器安装不平整问题的仿真结果则对试验数据的处理分析提供了帮助,有助于分析异常数据的情况及可能产生的原因。这些关键流场问题的仿真都具有实际意义。针对在激波管试验或实际爆炸场冲击波测试中产生的应力波干扰,利用分离式霍普金森压杆(SHPB)装置对压力传感器的应力波效应进行了试验研究。试验中将压力传感器侧向安装于透射杆之上,用落锤方式加载,使产生的应力波能侧向输入压力传感器。当落锤释放角度增大后,输入应力幅值和压力传感器输出信号同时增大,而二者比值传递率也增加,试验中最大输出值超过传感器满量程的10%,对传感器危害很大。利用尼龙和有机玻璃两种高聚物材料设计制造了应力波隔离座,并进行了试验,试验结果表明尼龙材料的隔离座能够有效隔离应力波造成的干扰,使传感器输出信号幅值、应力输入信号幅值及传递率都显著减小,这对于实际测试中应力隔离方案有参考价值。利用高聚物材料的本构模型进行了数学仿真计算,在对模型输入应力波信号后观察输出信号,输出信号与实测信号相似,同时结果对选择隔离材料提供了参考依据。
[Abstract]:Dynamic pressure calibration technology is the key to ensure the accuracy of dynamic pressure measurement. Shock tube calibration device is the most widely used in dynamic pressure calibration technology. Many countries in the world recommend the use of shock tube device for dynamic pressure calibration. Therefore, it is significant to improve the calibration accuracy of shock tube. In this paper, several key problems affecting the accuracy of dynamic pressure calibration of shock tube are studied, which are mainly carried out by theoretical analysis, experimental verification and numerical simulation analysis. The main work and conclusions are as follows: the dynamic pressure calibration technique of shock tube and the method to obtain the dynamic characteristics of pressure sensor are introduced. Then the derivation process of classical Rankine-Hugoniot overpressure formula for calculating the amplitude of dynamic pressure signal is introduced. Three factors that lead to the error in calculating the pressure amplitude are analyzed, which are the variation of specific heat ratio K value of the medium. The energy loss along the path of shock wave propagation and the non-ideal equation of state of gas in the medium after shock wave are not ideal, and the error caused by the unideal state of the gas after shock wave is the greatest. The compression factor of the actual gas state is calculated by using the virial equation, which is in accordance with the actual situation and including the parameters of the moisture content of the air, and the compression factor is substituted into the modified formula for calculating the overpressure. The overpressure of shock wave calculated by modified formula is closer to the measured value of shock tube test. The experimental results show that the calculation method of overpressure taking into account the actual gas state is an effective attempt. The finite element method (FEM) is used to simulate some key flow field problems in shock tube. The common finite element software FLUENT is used as a platform to simulate the problems of tube section shape, film breaking opening size, shock wave attenuation along the path and sensor installation unevenness. The simulation results of the cross section shape of the tube provide a reference for the design and manufacture of the shock tube. The simulation results of the size of the film breaking and the attenuation of the shock wave along the path have a certain reference significance for the setting of the test scheme of the shock tube. The simulation results of sensor installation unevenness are helpful to the processing and analysis of the experimental data, and to the analysis of the abnormal data and the possible causes. The simulation of these key flow field problems is of practical significance. In view of the stress wave interference produced in shock tube test or shock wave test of actual explosion field, the stress wave effect of pressure sensor was experimentally studied by using split Hopkinson pressure bar (SHPB) device. In the experiment, the pressure sensor is installed laterally on the transmission rod, and loaded with drop hammer, the generated stress wave can be input into the pressure sensor laterally. When the angle of drop weight release increases, both the input stress amplitude and the output signal of the pressure sensor increase simultaneously, and the ratio transfer rate of the two increases. The maximum output value in the test exceeds 10 percent of the full range of the sensor, which is very harmful to the sensor. The stress wave isolator is designed and manufactured by using nylon and plexiglass polymer materials. The test results show that the isolator of nylon material can effectively isolate the interference caused by stress wave and make the sensor output signal amplitude. The amplitude and the transfer rate of the stress input signal are reduced significantly, which is of reference value for the stress isolation scheme in the actual test. Using the constitutive model of polymer material, the mathematical simulation calculation is carried out. The output signal is observed after the stress wave signal is input to the model. The output signal is similar to the measured signal, and the result provides a reference for the selection of isolating material.
【学位授予单位】：中北大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP212

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