【摘要】：為增加對高度欠膨脹射流物理流動規(guī)律,特別是對其近場瞬態(tài)結(jié)構(gòu)特征的認識,利用基于Open FOAM函數(shù)庫開發(fā)的可壓縮流動求解器astro Foam,對噴壓比(NPR)分別為5.60,7.47,9.34,11.21,雷諾數(shù)Re約105的高度欠膨脹射流進行了三維大渦模擬。首先討論了射流近場的時均流動特征,發(fā)現(xiàn)大渦模擬計算成功捕捉到了高度欠膨脹射流近場的典型結(jié)構(gòu),并與實驗測量和文獻結(jié)果吻合較好。重點研究了高度欠膨脹射流近場的瞬態(tài)非定常特征,給出了實驗難以測量的射流近場波系結(jié)構(gòu)的建立過程,發(fā)現(xiàn)其主要受初始條件的主導(dǎo),噴壓比的影響較為有限。揭示了馬赫桶內(nèi)精細的小尺度胞格結(jié)構(gòu),并通過高速脈沖紋影圖片予以初步證實。定量地研究了射流馬赫盤的振蕩特征,發(fā)現(xiàn)其具有強瞬態(tài)和高非線性的特點,不同噴壓比下馬赫盤的振蕩周期相同,主要受f=5.298k Hz的軸對稱模態(tài)的主導(dǎo)。
[Abstract]:In order to increase the understanding of the physical flow law of highly underexpanded jet, especially the characteristics of its near-field transient structure, the three-dimensional large vortex simulation of the highly underexpanded jet with injection pressure ratio (NPR) of 5.60, 7.47, 9.34, 11.21 and Reynolds number Re about 105 is carried out by using the compressible flow solver astro Foam, developed based on Open FOAM function library. Firstly, the time-averaged flow characteristics of the jet near the field are discussed, and it is found that the typical structure of the near field of the highly underexpanded jet is successfully captured by the large vortex simulation calculation, and the results are in good agreement with the experimental results and the literature results. The transient unsteady characteristics of the near field of the highly underexpanded jet are studied, and the establishment process of the near field wave system structure of the jet, which is difficult to be measured by experiments, is given. It is found that the structure of the jet near field is mainly dominated by the initial conditions, and the influence of the jet pressure ratio is limited. The fine small scale cell structure in the Mach bucket is revealed and preliminarily confirmed by the high speed pulse schlieren picture. The oscillation characteristics of jet Mach disk are studied quantitatively. It is found that it has the characteristics of strong transient and high nonlinear. The oscillation period of Mach disk is the same under different injection pressure ratios, which is mainly dominated by the axisymmetric mode of f 鈮，

本文編號：2498716