Research On The Swirl Combustion Technology Of Powdered Fuel Water Ramjet

The trans-water-air medium missile and underwater ultra-high speed torpedo are the strategic frontier at present,and the powder-fuel water ramjet is the key power technology restricting the development of both.Based on the research background of powder-fuel water ramjet ignition and stable combustion,and the design of two-stage inlet swirl combustion chamber as the research object,the swirl combustion technology of water ramjet was studied by combining theoretical analysis,ignition experiment and numerical study.In order to meet the demand of underwater ultra-high speed cruise and the ramjet across water-air medium,the overall scheme of underwater variable thrust ultra-high speed torpedo and the powder fuel water ramjet are designed in this paper.The engine ignition system,powder supply structure and two-stage swirl inlet combustion chamber are designed in detail.The influence of different water-fuel ratio and combustion chamber pressure on engine specific impulse performance is analyzed through theoretical calculation,which provides theoretical basis for the following ignition experiments.Through the integration of stamping water supply system,control system and powder supply system,a powder fuel water ramjet experiment system is established,which is suitable for the water ramjet.The powder flow calibration,inlet flow calibration and timing commissioning experiments of the test system were carried out,and the relationship between water flow and injection pressure drop,injection delay time and other key parameters were obtained,which laid a foundation for the ground ignition test and performance analysis of the engine.The short-range and long-range ignition experiments on the powder fuel water ramjet engine are carried out respectively.The short-range ignition experiments results show that the timing design of ignition,powder supply and water supply is significant to the successful ignition and stable operation of the engine.In order to establish the pressure and heat environment in the swirl combustion chamber and make the combustion reaction occurred successfully between powder fuel and water,the timing design should make the gas generator work in advance.The gas generator 15 s long-range ignition experiment was carried out by adjusting the work timing of water ramjet engine.The results show that the water ramjet engine can start up and run stable when the gas generator works in advance for 2.1s relative to water injection.When the magnesium-water combustion reaction established successfully,the combustion chamber first passes the pressure climbing stage,and then enters the stable combustion stage.In the stable combustion stage,the interaction between water flow rate and combustion chamber pressure makes the combustion chamber pressure fluctuates periodically in a small range.The particle surface reaction model and EDC turbulent combustion model were used to simulate the swirl combustion chamber.By comparing the experimental results with the numerical simulation results,the effectiveness of the numerical simulation method is verified,which can be used to analyze the variation rule of different parameters on the combustion chamber performance.Finally,numerical simulation was carried out to study the flow field and combustion performance in combustion chamber with different primary swirl inlet angle and different primary and secondary swirl inlet water ratio.The results show that with the increase of first-order swirl angle,the length of the central circulation zone is basically unchanged,but the vortex structure scale and swirl intensity in the central circulation zone gradually decrease.The optimum primary swirl inlet angle exists between 45°and 60°,which results in the highest performance of the combustion chamber.With the increase of secondary cyclone inflow,the structure scale of the central circulation zone increases.Under the condition that the water-fuel ratio is constant and the primary swirl water intake is sufficient,appropriately increasing the secondary swirl water intake ratio can improve the mixing combustion effect in the central circulation zone and improve the performance of the swirl combustion chamber.