Research On Self-pressurization Scheme Based On Regenerative Cooling

Self-pressurization supply system combines the advantages of low complexity of pressure-fed system,with the performance of pump-fed system by its low system weight and high supply pressure.It holds the promise of low complexity propulsion systems for highly reliable and cost-effective vehicle designs.However,there is also a problem that the classical self-pressurization is unable to supply propellant with constant pressure,thus consequently is difficult to output constant thrust.In this paper,a preliminary study of the self-pressurization scheme based on regenerative cooling is proposed and studied by using numerical simulation and theoretical analysis.The improved scheme of self-pressurization supply system is investigated,which includes research on factors affecting the pressure of tank and flow and heat transfer characteristics under subcritical pressure condition,which provides a reference for the future study.The main work of this paper is as follows:(1)Comparison of constant pressure supply schemes is carried out.The working principle of self-pressurized tank is introduced.The weights of three kind of constant pressure supply systems are estimated and compared.Results show that the regenerative cooling scheme system has the lowest weight of the three,which is about 1/4 of the bottle extrusion system.(2)Numerical simulation of the pressure variation law of the tank in the supply process is carried out.The physical and mathematical model of the propellant tank is established,and the calculation method of the thermodynamic parameters of the propellant is introduced.The corresponding calculation program is coded.The model's prediction is in good agreement with the experimental data.Through different examples,the factors affecting the pressure of the tank are analyzed: The volume flux of propellant and the volume flux of pressurized gas are important.The influence of liquid propellant temperature and net evaporation rate is negligible for gas bottle pressurization,nevertheless,it is important for a self-pressurized tank.The volume of vapor in the tank affects the sensitivity of pressure,the larger the volume,the smaller the effect of the other factors.The effect of vapor heating is better than that of the liquid heating when a tank heater is used.(3)Numerical simulation of the flow and heat transfer process of the propellant at subcritical pressure is carried out.A one-dimensional homogeneous flow model of propellant in cooling channel is established,and the corresponding calculation program is coded.The factors affecting the performance of the channel are analyzed by the model.Results show that,for propellant at subcritical pressure,there is usually a dry up point where wall temperature increases a lot in the channel.The cooling passage should be arranged in an area of lower heat flux or outside the heat insulating layer to ensure that the temperature difference of wall at dry up point is not too large.In this case,the propellant in the channel is allowed to vaporize completely and more vapor is obtained for pressurization.