【摘要】：通過電磁場與流場的相互作用對飛行器表面流場進行有效的控制,這是一種全新的流動控制方法。該方法與傳統(tǒng)的表面氣流接觸式流動控制方式相比,其突出優(yōu)點在于不會額外改變飛行器的氣動外形,因而在航空航天領(lǐng)域,特別是在超聲速飛行的流動控制方面具有很大發(fā)展空間及應(yīng)用前景。針對鈍體超聲速飛行中所產(chǎn)生的高壓、高熱以及高阻力等問題,已有的研究表明通過改變飛行器前端流場特別是改變飛行器前端弓形激波的形態(tài),能夠有效的改善上述問題。以此為目的,本文著力研究幾類電磁場對典型半球體外形超聲速繞流場的影響,探討超聲速飛行中的磁流體控制方法。通過求解三維磁流體方程組,對超聲速情況下半球體的繞流場進行模擬,分別研究了偶極子磁場、均勻磁場和有攻角飛行時的流場及外形氣動特性,具體內(nèi)容如下:首先,研究不同強度的偶極子磁場與繞流場的相互作用,主要分析了不同條件下繞流流場結(jié)構(gòu)、駐點延伸線上各狀態(tài)參數(shù)以及半球體阻力的變化。結(jié)果顯示,半球體的不同截面的流場具有對稱性。隨著磁場強度增加,激波脫體距離增加,阻力系數(shù)降低,在激波層和半球體之間,半球體兩側(cè)處壓強、密度和溫度等參數(shù)數(shù)值逐漸降低。其次,研究不同強度條件下均勻磁場對超聲半球體繞流的影響。結(jié)果表明,在一定范圍內(nèi),隨著均勻磁場強度的增加,弓形激波兩側(cè)逐漸變寬,激波脫體距離增加,飛行器阻力系數(shù)下降。當(dāng)磁場強度較大時,阻力系數(shù)最多下降了20%。另外,在半球體頭部駐點處,壓強和密度隨磁場強度增大逐漸減小。最后,研究有攻角飛行時,偶極子磁場對超聲速繞流場的作用。主要分析不同攻角、不同磁場強度情況下流場結(jié)構(gòu)的變化。研究發(fā)現(xiàn),在同一攻角情況下,隨著磁場強度的增加,激波脫體距離逐漸增加,阻力系數(shù)逐漸降低,呈線性變化。在同一磁場強度條件下,隨著攻角的增加,弓形激波逐漸傾斜,阻力系數(shù)逐漸降低,且各狀態(tài)參數(shù)沿駐點延伸線無規(guī)律性變化。上述研究補充了磁流體力學(xué)在流動控制數(shù)值模擬的研究成果,為進一步在航天航空領(lǐng)域應(yīng)用提供參考數(shù)據(jù),因而具有一定的理論及實際意義。
[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.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：V219

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