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699 results on '"Wang, Fengshan"'

52. Effect of the MoSi2 coating on operational reliability of bipropellant rocket engine

Author

Cai Kun, Zhang Zhen, Wang Na, Hu Yu, and Wang Fengshan

Subjects
bipropellant rocket engine, mosi2 coating, liquid film cooling, mo layer residue, Environmental sciences, GE1-350
Abstract

This present study investigated the MoSi2 coating and its effect on reliability of bipropellant rocket engine. This coating is developed to protect the chamber substrate material form oxidization under hightemperature oxidative circumstance as bipropellant engine works. The multilayer structure of the MoSi2 coating shows excellent high-temperature and thermal-cycle resistance. Its characteristic of self-healing leads to the good performance under the long-time steady working condition for rocket engines. A 25000-seconds firing test was conducted to testify the performance of MoSi2 coating under high temperature above 1400℃. In addition, the influence of coating surface morphology on liquid film cooling was fully discussed in experiment and simulation. High-speed microscopy camera was used to study the effects of Weber number on the spreading and lasting of cooling liquid-film. the simulative comparison was conducted by OpenFOAM to present different transfer-heat modes, when a droplet impinges on the high-temperature surface of MoSi2 coating. All results show that higher smoothness of the coating is suitable for liquid-film cooling, strengthening liquid film spread and heat transfer. Moreover, scanning electron microscope (SEM) was used to study the effect of Mo layer residue on the coating thermal-cycle profermance. The test results indicates that Mo layer residue significantly cause penetrating cracks of the coating and then weaken the self-healing of the coating at downstream of throat. Therefore, it is important to strictly control the thickness of Mo layer by means of matching Mo target in ion plating. Thus after properly prolonging the infiltration time, Mo layer can be silicified completely without residue.

Published
2021
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71. Simulating electrohydrodynamics with smoothed particle hydrodynamics based on a charge-conservative approach

Author

Chen Fu-Zhen, Liu Hu, Qiang Hong-Fu, Wang Ping, and Wang Fengshan

Subjects
Physics, Charge conservation, Applied Mathematics, Physics::Medical Physics, General Engineering, Charge density, Charge (physics), 02 engineering and technology, Mechanics, 01 natural sciences, 010101 applied mathematics, Smoothed-particle hydrodynamics, Computational Mathematics, 020303 mechanical engineering & transports, 0203 mechanical engineering, Boundary value problem, Electric potential, Electrohydrodynamics, 0101 mathematics, Poisson's equation, Analysis
Abstract

This paper presents an EHD model for SPH based on a charge-conservative approach. Compared with the leaky dielectric model, the EHD model used in this paper was charge conserved, since no term in the charge conservation equation was neglected. An implicit SPH formula for calculating the electric potential from the electrical properties of the previous time step was constructed, based on the electric potential Poisson equation and the charge conservation equation. The SPH formulas of the electric field and the charge density were also presented. To implement the EHD boundary condition accurately, a scheme, with two kinds of EHD boundary dummy particles, was developed. Both static and hydrodynamic numerical tests were conducted, and the accuracy of the proposed EHD model for SPH was verified by comparison with the results of analysis, the FVM method and the existing ISPH with the leaky dielectric model. This study provides an efficient method for simulating complex EHD problems with SPH.

Published
2021

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