Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： The high-level rocket lift-off noise induced by the hypersonic jet has adverse impacts on thestructural security and equipment reliability of the rocket ;therefore , it is of great significance to make theprediction and reduction of high-speed jet noise environment. A numerical analysis method based on de-tached eddy simulation ( DES) turbulence model and combined transport equation, discrete phase model(DPM) and FW-H equation was established to calculate the noise of multi-components rocket jet and wa-ter considering evaporation inserts multi-components high speed jet. The prediction pf hypersonic jet flowcondition and noise environment of liquid rocket engine was completed.'The results show that the eror be-tween the predicted results and experimental results of overall sound pressure level of probes is within�3 dB.Furthermore , the annular water inserts noise reduction system was designed , the noise reductionlaw of water involved in high Mach number jet , considering evaporation effect and influence of complex deflector duct configuration , was studied , which reveals that shearing effect , momentum transfer and evapora-tion are important incentives for noise reduction.Besides , the noise suppression effect increases monoton-ously with the increase of mass flow rate , and increases first and then decreases with the increase of inter-vention angle.This study is of great importance in design and engineering of the water inserts system.
Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： A newly developed composite projectile designed to simulate cased explosive's combined load-ing and numerical method were implemented to study dynamic behavior of Weldox 460 E steel corrugatedcore sandwich beam subjected to combined blast and impact loading.Finite element modeling setting wasvalidated based on published experimental and numerical results. By comparing the ballistic limit differ-ence between the composite projectile and the flat-headed fragment simulation projectile ( FSP) , it is foundthat the ballistic limit of the cornugated sandwich beam is higher when subjected to the composite projectilethan that under the single fragment simulation projectile condition. The main causes of the difference ofballistic limits are also explored. A parametric study was conducted and the influence of loading time in-terval on the target's ballistic limit , the mid-span displacement of the back face sheet and the energy absorbed from FSP was explored,which provides a reference for the design of corugated sandwich beam asprotective structure under combined blast and impact loading.
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