Liquid jets are considered issuing from single-hole, round nozzles into quiescent gases under conditions such that they break up into a well defined conical spray immediately at the nozzle exit plane. The initial angles of such sprays were measured at room temperature by a spark photography technique. Water, n-hexane, and n-tetradecane at pressures from 11.1 MPa to 107.6 MPa were injected into gaseous N2 at pressures from 0.1 MPa to 4.2 MPa through sixteen nozzles of different geometry. Under the test conditions, the spray angle is found to be a strong function of the nozzle geometry and the gas-liquid density ratio and a weak function of the injection velocity. The measured trends are then discussed in the light of possible mechanisms of the breakup process and shown to be compatible with the aerodynamic theory of surface breakup if modified to account for nozzle geometry effects.

No abstract

This paper begins with experiments to investigate the behind-target damage effects on sandwich-like plates subjected to reactive liner shaped charge jet. Sandwich-like plates, consisting of triple spaced aluminum plates filled with flame-retardant foams, are placed under a steel target. The reactive liner shaped charge is initiated at a stand-off of 1.0 CD, producing a reactive jet to perforate the steel target and then cause behind-target damage effects on sandwich-like plates. The experimental results show there is an unusual rupturing effect on sandwich-like plates, which strongly depends upon the steel target thickness. Generally, the rupturing effects on sandwich-like plates increase gradually with the steel target thickness decreasing from 60 mm to 40 mm. Then, the interaction mechanism between the reactive jet and target is discussed in three phases. The formation phase shows an expansion behavior of reactive jet, leading to the jet density less than the initial density. The penetration phase results in central holes on aluminum plates and provides a precondition for cracks. Then, the deflagration reaction phase causes a field of high temperature and high pressure inside the sandwich-like plates, which enlarges the kinetic energy-induced pre-perforations and thereby causes the unusual rupturing effects. Finally, an analytical model for the rupturing damage to aluminum plate is developed and the relevant parameter is obtained approximately.

No abstract

To reveal the expansion phenomenon and reaction characteristics of an aluminum particle filled polytetrafluoroethylene (PTFE/Al) reactive jet during the forming process, and to control the penetration and explosion coupling damage ability of the reactive jet, the temperature and density distribution of the reactive jet were investigated by combining numerical simulation and experimental study. Based on the platform of AUTODYN-3D code, the Smoothed Particle Hydrodynamics (SPH) algorithm was used to study the evolution behaviors and distribution regularity of the morphology, density, temperature, and velocity field during the formation process of the reactive composite jet. The reaction characteristic in the forming process was revealed by combining the distribution of the high-temperature zone in numerical simulation and the Differential Scanning Calorimeter/Thermo-Gravimetry (DSC/TG) experiment results. The results show that the distribution of the high-temperature zone of the reactive composite jet is mainly concentrated in the jet tip and the axial direction, and the reactive composite jet tip reacts first. Combining the density distribution in the numerical simulation and the pulsed X-ray experimental results, the forming behavior of the reactive composite jet was analyzed. The results show that the reactive composite jet has an obvious expansion effect, accompanied by a significant decrease in the overall density.