【正文】
與展望本文著眼于在激波管中進行RichtmyerMeshkov不穩(wěn)定性實驗,并采取有效的光學(xué)拍攝手段(黑白紋影、彩色紋影)對界面失穩(wěn)過程進行了拍攝,得到了初步的實驗結(jié)果。概括起來本文工作主要包括以下幾個方面:(1)、對界面的形成進行了探索,配置出了滿足實驗要求的肥皂液。實驗過程中采用的氦氣泡,既能有效地隔離兩種不同的流體介質(zhì),又要盡可能減少隔離物在界面運動過程中的影響,還要保持所需的初始界面形狀,而對于初始擾動采取激波和氣體界面在相遇時的曲率偏差來實現(xiàn)。這種采用肥皂泡隔離氣體的方法,不但能較好地滿足實驗的要求,還具有裝置簡單,成本低廉等優(yōu)點。(2)、利用紋影的辦法,拍攝得到了激波和球狀界面和柱狀界面相互作用導(dǎo)致界面失穩(wěn)的整個過程。分析了界面變形的原因,并對所得的渦結(jié)構(gòu)進行了分析,指出主要是斜壓機制所致。還就球狀氣泡失穩(wěn)后所得的渦環(huán)結(jié)構(gòu)和柱狀氣泡的渦結(jié)構(gòu)進行了對比,指出對于柱狀界面更利于紋影系統(tǒng)的拍攝,為以后在此平臺開展界面不穩(wěn)定性實驗提供了一定實驗依據(jù)。同時,需要看到,在實驗中尚存在若干問題需要解決,如重力給球形氣泡帶來的形變;肥皂膜破裂對流場的影響等等,都可能影響最終實驗的準(zhǔn)確性。同時,可以看到,由于觀察窗長度的限制,界面失穩(wěn)的后期過程還沒有得到,這都有待于進一步改進。在解決這些問題后,可望對該系統(tǒng)逐步進行完善,使得所建立的平臺即可以開展平面運動激波與界面的相互作用實驗,也可以生成圓柱面激波與氣體界面的相互作用實驗;同時,采取改進的流動顯示技術(shù),如激光全息干涉,激光誘導(dǎo)熒光顯示技術(shù)等,得到瞬態(tài)下流場精細結(jié)構(gòu)的照片。 參考文獻[1] R. D. Richtmyer, Taylor instability in shock acceleration of pressible fluids. Commun. Pure Appl. Math. 13 :297–319,1960.[2] Meshkov, Instability of the interface of two gases accelerated by a shock wave. Transl. of Izv. Acad. Sci. USSR Fluid Dyn. 4, 101104, 1969[3] and . PLIF flow visualization of inpressible Richtmyer Meshkov instability. In Proceedings of the Fourth Microgravity Fluid Physics, pages 528533,Cleveland,Ohio,1998.[4] ,and . Potential flow models of RayleighTaylor and RichtmyerMeshkov bubble fronts. ,6:40194030,1994.[5] . RayleighTaylor stability for a normal shock wavedensity discontinuity interaction. ,29(2):376386,1986.[6] and . Nonlinear perturbation theory of the inpressible RichtmyerMeshkov .,70(17):31123115,1996.[7] Zhang Qiang , Sohn S. An analytical nonlinear theory of RichtmyerMeshkov instability . Physical Letters A,1996,212:149 155.[8] K .A. Meyer, . Blewet, Numerical investigation of the stability of a shock accelerated interface between two fluids .,1972,1 5:753.[9] . Cloutman and . Weimer, Numerical simulation of RichtmyerMeshkov instabilities. Phys. Fluids,1993,4 :1821.[10] Richard L. Holmes, John W. Grove and David H. Sharp, Numerical investigation of RichtmyreMeshkov instability using front tracking. J. Fluid ,301:51.[11] . Zabusky, . Kotelnikov, Y. Gulak and GZ. Peng, Amplitude growth rate of RichmyreMeshkov unstable twodimensional interface to intermediate times, J .Fluid Mech,2003,475:147.[12] and , RichtmyerMeshkov instability induced by shockbubble interaction:Numerical and analytical studies with experimental validation. , 036102 (2006).[13] . Experimental observations of shock stability and shock induced turbulence. Advances in Compressible Turbulent Mixing. Pages 341348.[14] Aleshin AN,Gamalii EG,Zaitsev G,et al ,Nonlinear and transitional stages in the on set of the RichtmyerMeshkov instability, Sov . Tech Phys. Lett,1988,14:466468.[15] and on the RichtmyerMeshkov instability: singlescale perturbations on a continuous interface. Mech.,263:271292,1994.[16] Haas JF, Sturtevan B,Interaction of weak shock waves with cylindrical and Spherical gas inhomogeneities . J. Fluid ,1 81:4176.[17] Devesh Ranjan. Experimental Investigation of the ShockInduced Distortion of a Spherical Gas Inhomogeneity. 2007.[18] 施紅輝,激波與界面作用實驗研究,LHD2007學(xué)術(shù)年會,中科院力學(xué)所,2007[19] G. Layes, G. Jourdan, and L. Houas, Distortion of a spherical gaseousinterface accelerated by a plane shock wave, Phys. Rev. Lett. 91, 174502, 2003.[20] J. ., Shockinduced mixing of a lightgas Mech. (1992), vol. 234. 629649.附錄 激波管參數(shù)計算matlab程序程序一:已知激波管高、低壓段壓比,計算激波馬赫數(shù)。syms ms %定義運動激波馬赫數(shù)p4=。 %定義高低壓斷的壓力值p1=。gama1=。 %定義1區(qū)和4區(qū)的比熱比gama4=。R=287。 %氣體常數(shù)T1=280。 %1區(qū)和4區(qū)的溫度值T4=280。a1=sqrt(gama1*R*T1)。 %當(dāng)?shù)芈曀俚挠嬎鉧4=sqrt(gama4*R*T4)。f=p4/p1(2*gama1/(gama1+1)*ms^2(gama11)/(gama1+1))*(1(gama41)/(gama1+1 )*(a1/a4)*(ms1/ms))^(2*gama4/(gama41)) %馬赫數(shù)和壓比之間的關(guān)系式ms=solve(f,ms)。 %求解上方程,得到激波馬赫數(shù)ms=vpa(ms,4)。 %化簡結(jié)果ms=ms(1)程序二:已知激波馬赫數(shù),計算激波管中各區(qū)參數(shù)。%參數(shù)的定義gama1=。 %定義1區(qū)和4區(qū)的比熱比gama4=。R=287。 %氣體常數(shù)T1=280。 %1區(qū)和4區(qū)的溫度值T4=280。p1=。 %低壓段壓力值ms=。 %激波馬赫數(shù) %當(dāng)?shù)匾羲俚挠嬎鉧1=sqrt(gama1*R*T1)。a4=sqrt(gama4*R*T4)。% 4區(qū)參數(shù)的確定p41=(2*gama1/(gama1+1)*ms^2(gama11)/(gama1+1))*(1(gama41)/(gama1+1)*(a1/a4)*(ms1/ms))^(2*gama4/(gama41))。p4=p1*p41 % 2區(qū)參數(shù)的確定p21=1+2*gama1/(gama1+1)*(ms^21)。p2=p1*p21t21=((2*gama1*ms^2(gama11))*((gama11)*ms^2+2))/((gama1+1)^2*ms^2)。t2=t1*t21 % 3區(qū)參數(shù)的確定m3=((a4/a1*(gama1+1)*ms)/(2*(ms^21))(gama41)/2)^(1)p3=p4*(1+(gama41)/2*m3)^(2*gama4/(gama41))t3=t4*(1+(gama41)/2*m3)^(2)a3=sqrt(gama4*r*t3)。v3=a3*m3v2