| LNG,as an environment friendly and efficient energy,has broad prospects in shipping and power.However,the safety problem of restricting the application of LNG needs to be solved.Corrugated-type fire-arrester,as a kind of safety devices installed in complex ship pipeline networks,can inhibit the spread of combustible gas flames.It is of great significance to the safety production on board.In this paper,the propagation and quenching process of LNG premixed deflagration flame in the flame arrester element were studied by taking the corrugated flame arrester as the research object.In this study,the corrugated-type fire-arrester element was simplified as a triangular prism slit.The transient process of propagating and quenching of methane/air premixed deflagration flame along the fire-arrester was analyzed by Fluent software,which was based on large eddy simulation and component transport model.And the influence of the design sizes and working conditions on the fire resistance performance of the fire-arrester was explored by changing the geometric characteristics and the boundary conditions of the model.It is found that the process of deflagration flame propagation in fire-arrester from ignition to quenching can be divided into four stages: initial stage,stretching stage,deceleration stage and low speed stage.The effects of various factors on the propagation and quenching process of flame in the fire-arrester were analyzed.Increasing the slit size,the wall temperature and the inlet flame velocity all contribute to the flame propagation.And the propagation distance of the flame is the farther while the bottom angle is close to 60°.The slit size and the bottom angle can be considered simultaneously by the hydraulic diameter.The larger the hydraulic diameter,the farther the quenching length,and there is an inverse proportion relationship between them.Under the same hydraulic diameter,the fire resistance performance of base angle 60 ° is better.The relationship between the inlet flame velocity and quenching length is approximately a quadratic radical curve.The larger the inlet flame velocity is,the farther the quenching length is.The relationship between wall temperature and quenching length can be expressed by natural logarithm.The quenching length increases with the increase of wall temperature.It is found that when the wall temperature is between 1150 k and 1300 k,the flame may keep stable propagation in the slit.Finally,the relationship between the hydraulic diameter,the inlet flame velocity,the wall temperature and the quenching length is obtained.In this paper,the influence of various factors on flame propagation and quenching process in corrugated-type fire-arrester is systematically studied,and the relevant mechanism is explained.The variations of quenching length with slit size,bottom angle,inlet flame velocity and wall temperature are obtained.And the fitting formula is used for quantitative analysis,which will provide a reference for the production,design and installation of corrugated-type fire-arrester. |
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