超声速半球体绕流磁流体流动控制数值模拟研究

发布时间：2018-11-29 14:04

【摘要】：通过电磁场与流场的相互作用对飞行器表面流场进行有效的控制,这是一种全新的流动控制方法。该方法与传统的表面气流接触式流动控制方式相比,其突出优点在于不会额外改变飞行器的气动外形,因而在航空航天领域,特别是在超声速飞行的流动控制方面具有很大发展空间及应用前景。针对钝体超声速飞行中所产生的高压、高热以及高阻力等问题,已有的研究表明通过改变飞行器前端流场特别是改变飞行器前端弓形激波的形态,能够有效的改善上述问题。以此为目的,本文着力研究几类电磁场对典型半球体外形超声速绕流场的影响,探讨超声速飞行中的磁流体控制方法。通过求解三维磁流体方程组,对超声速情况下半球体的绕流场进行模拟,分别研究了偶极子磁场、均匀磁场和有攻角飞行时的流场及外形气动特性,具体内容如下:首先,研究不同强度的偶极子磁场与绕流场的相互作用,主要分析了不同条件下绕流流场结构、驻点延伸线上各状态参数以及半球体阻力的变化。结果显示,半球体的不同截面的流场具有对称性。随着磁场强度增加,激波脱体距离增加,阻力系数降低,在激波层和半球体之间,半球体两侧处压强、密度和温度等参数数值逐渐降低。其次,研究不同强度条件下均匀磁场对超声半球体绕流的影响。结果表明,在一定范围内,随着均匀磁场强度的增加,弓形激波两侧逐渐变宽,激波脱体距离增加,飞行器阻力系数下降。当磁场强度较大时,阻力系数最多下降了20%。另外,在半球体头部驻点处,压强和密度随磁场强度增大逐渐减小。最后,研究有攻角飞行时,偶极子磁场对超声速绕流场的作用。主要分析不同攻角、不同磁场强度情况下流场结构的变化。研究发现,在同一攻角情况下,随着磁场强度的增加,激波脱体距离逐渐增加,阻力系数逐渐降低,呈线性变化。在同一磁场强度条件下,随着攻角的增加,弓形激波逐渐倾斜,阻力系数逐渐降低,且各状态参数沿驻点延伸线无规律性变化。上述研究补充了磁流体力学在流动控制数值模拟的研究成果,为进一步在航天航空领域应用提供参考数据,因而具有一定的理论及实际意义。
[Abstract]:The surface flow field of aircraft is effectively controlled by the interaction of electromagnetic field and flow field, which is a new flow control method. Compared with the traditional surface airflow contact flow control method, this method has the outstanding advantage that it will not change the aerodynamic shape of the aircraft, so it is in the field of aeronautics and astronautics. Especially in the flow control of supersonic flight, there is a great development space and application prospect. In view of the problems of high pressure, high heat and high resistance caused by the blunt body supersonic flight, it has been shown that the above problems can be effectively improved by changing the front flow field of the aircraft, especially by changing the shape of the bow shock wave in the front end of the vehicle. For this purpose, the influence of several kinds of electromagnetic fields on the supersonic flow field around a typical hemispherical shape is studied, and the control method of magnetic fluid in supersonic flight is discussed. By solving the three-dimensional magnetohydrodynamic equations, the flow field around the semi-sphere at supersonic velocity is simulated, and the aerodynamic characteristics of the flow field and the shape of the semi-sphere are studied respectively when the dipole magnetic field, the uniform magnetic field and the angle of attack are flying. The main contents are as follows: first, The interaction between dipole magnetic field and flow field with different intensity is studied. The variation of flow field structure, state parameters and hemispherical drag are analyzed under different conditions. The results show that the flow field of different sections of hemispherical body has symmetry. With the increase of the magnetic field intensity, the distance of the shock wave is increased, the drag coefficient decreases, and the pressure, density and temperature decrease gradually between the shock layer and the hemispherical body. Secondly, the effect of uniform magnetic field on the flow around the ultrasonic hemispherical body is studied. The results show that, in a certain range, with the increase of uniform magnetic field intensity, the two sides of the bow shock wave become wider gradually, the distance of the shock wave is increased, and the drag coefficient of the aircraft decreases. When the magnetic field intensity is large, the resistance coefficient decreases by 20% at most. In addition, the pressure and density decrease with the increase of the magnetic field intensity. Finally, the effect of dipole magnetic field on supersonic flow field in flight with angle of attack is studied. The change of flow field structure under different attack angle and magnetic field intensity is analyzed. It is found that at the same angle of attack, with the increase of the magnetic field intensity, the distance of the shock wave is gradually increased, and the drag coefficient decreases gradually, showing a linear change. Under the condition of the same magnetic field intensity, with the increase of the angle of attack, the bow shock wave tilts gradually, the resistance coefficient decreases gradually, and the state parameters do not change regularly along the extension line of the stationary point. The above research complements the research results of MHD in numerical simulation of flow control, and provides reference data for further application in aerospace field, so it has certain theoretical and practical significance.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V219

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