Powder-Fueled Water Ramjet Engine(PFWRE)is of great attraction for high-speed and long-voyage underwater propulsion,as well as air–water trans-media navigation applications due to its high energy density and thrust a...Powder-Fueled Water Ramjet Engine(PFWRE)is of great attraction for high-speed and long-voyage underwater propulsion,as well as air–water trans-media navigation applications due to its high energy density and thrust adjustability.However,the complex multiphase combustion process in the combustor significantly affects engine performance.In this study,a detailed model for aluminum particle combustion in water vapor is developed and validated via literature data as well as the ground direct-connected test we conducted.Thereafter,the numerical study on the multiphase combustion process inside the aluminum-based PFWRE combustor is carried out within the Euler–Lagrange framework using the developed model.Results show that a reverse rotating vortex pair before the primary water injection causes particles to flow back towards the combustor head and leads to product deposition.Aluminum particles external to the powder jet have shorter preheating time than internal particles and burn out in advance.The analysis of the particle combustion process indicates that the flame structure inside the combustor consists of the particle preheating zone,the surface combustion heat release zone,the gas-phase combustion heat release zone,and the post-flame zone.In the present configuration,as the particle size increases from 10μm to 20μm,the preheating zone length increases from 35 mm to 85 mm.Meanwhile,heat release from gas-phase combustion decreases,and the average temperature of the combustor head first increases and then decreases.This study not only provides insight into the multiphase combustion characteristics of the aluminum-based PFWRE combustor but also offers guidance for the design of the combustion organization schemes and engine structure optimization.展开更多
The optimization method of a mathematical model and connected-pipe experimental technique for a test in altitude test facility (ATF) of a liquid fuel ramjet engine was researched.The optimization of the simple mathema...The optimization method of a mathematical model and connected-pipe experimental technique for a test in altitude test facility (ATF) of a liquid fuel ramjet engine was researched.The optimization of the simple mathematical model was divided into two steps.Firstly,using the test engine's geometry configuration size data,a preliminary adjustment was done.Secondly,using experimental test data,the components' experiential coefficients were modified appropriately.Emphasis was laid on the simulation technique of flight condition and parameters measurement method.The experimental technique was applied to a ramjet ATF test successfully.The comparison results show that the optimized-model has higher precision and the nozzle gross thrust difference drops from 12% to about 4%.展开更多
A performance study of a water ramjet engine is described.The engine is powered by the reaction of a magnesium-based propellant and ingested water.In this study,a solid propellant,which consisted of a large percentage...A performance study of a water ramjet engine is described.The engine is powered by the reaction of a magnesium-based propellant and ingested water.In this study,a solid propellant,which consisted of a large percentage of magnesium,a binder and a small amount of oxidant,was used as a hydro reactive fuel.Cold water was injected into the combustion chamber as a main oxidant.A scaled-down experimental engine was tested in a direct-connect ground testing system to characterize the factors influencing the engine performance.The results show that the increasing of total water/fuel ratio,an addition of secondary water intake along the combustion chamber,a larger magnesium content in the solid propellant,a smaller primary water injection angle towards the coming main flow,and a higher primary injection pressure were all able to promote the engine performance.The maximum engine performance was obtained in test 08,and with all tests,an appropriate set of parameters and conditions for the optimum engine performance were determined展开更多
The main interest in the current study focuses on the possibility of overspeeding for the gas-generator cycle air turbo ramjet(GG-ATR)engine.The authors developed the air turbo ramjet engine and investigated its compr...The main interest in the current study focuses on the possibility of overspeeding for the gas-generator cycle air turbo ramjet(GG-ATR)engine.The authors developed the air turbo ramjet engine and investigated its compressor performance.Based on those data,the authors developed the analytical code for the air turbo ramjet engine,which calculates the performances of turbomachinery,gas-generator,and ram combustor.The previous study described that the rotor overspeeding would not occur in the air turbo rocket engine.However,the current results show that degraded ram combustion can decrease the compressor pressure ratio and the compressor power.This reduced compressor power can cause overspeeding for the air turbo ramjet engine.The experimental results of compressor power and turbine inlet pressure support those analytical results.展开更多
This study investigates the mixing enhancement mechanism and propagation characteristics of the detonation flow field of a Rotating Detonation Engine(RDE).Three-dimensional numerical simulations of a non-premixed ramj...This study investigates the mixing enhancement mechanism and propagation characteristics of the detonation flow field of a Rotating Detonation Engine(RDE).Three-dimensional numerical simulations of a non-premixed ramjet-based RDE fueled by gaseous ethylene are performed in OpenFOAM for configurations with 15,30,45,and 60 orifices at a flight Mach number of 4.The results show that fuels with a stripped distribution are primarily mixed via tangential diffusion in the cold flow field.The configuration with more orifices has a better upstream mixing efficiency,whereas its downstream mixing efficiency,which is limited by the depth of penetration,is difficult to improve further.Backward Pressure Perturbations(BPPs)opposite to the propagation direction of Rotating Detonation Waves(RDWs)are produced by the reflection of the upstream oblique shock wave with the incoming stream and the hot release of local reactions after RDWs,which significantly affects the propagation mode and mixing.The RDWs propagate in the stable single-wave mode in configurations with 45 or 60 orifices and in the multi-wave mode in configurations with 30 orifices,whereas they fail in configurations with 15 orifices.Compared with that in the cold flow field,deceleration of the main flow,pressurization,and tangential velocity perturbation caused by the RDW substantially enhance the mixing efficiency.Moreover,the tangential velocity perturbations of upstream oblique shock waves and BPPs reduce the unevenness of the fuel distribution for the next cycle.This study reveals the mixing enhancement mechanism of RDWs and can contribute to the design of the injection scheme of the RDE.展开更多
We investigate experimentally and analytically the combustion behavior of a high-metal magnesium-based hydro- reactive fuel under high temperature gaseous atmosphere. The fuel studied in this paper contains 73% magnes...We investigate experimentally and analytically the combustion behavior of a high-metal magnesium-based hydro- reactive fuel under high temperature gaseous atmosphere. The fuel studied in this paper contains 73% magnesium powders. An experimental system is designed and experiments are carried out in both argon and water vapor atmo- spheres. It is found that the burning surface temperature of the fuel is higher in water vapor than that in argon and both of them are higher than the melting point of magnesium, which indicates the molten state of magnesium particles in the burning surface of the fuel. Based on physical considerations and experimental results, a mathematical one-dimensional model is formulated to describe the combustion behavior of the high-metal magnesium-based hydro-reactive fuel. The model enables the evaluation of the burning surface temperature, the burning rate and the flame standoff distance each as a function of chamber pressure and water vapor concentration. The results predicted by the model show that the burning rate and the surface temperature increase when the chamber pressure and the water vapor concentration increase, which are in agreement with the observed experimental trends.展开更多
基金supported by the National Natural Science Foundation of China(No.22305053).
文摘Powder-Fueled Water Ramjet Engine(PFWRE)is of great attraction for high-speed and long-voyage underwater propulsion,as well as air–water trans-media navigation applications due to its high energy density and thrust adjustability.However,the complex multiphase combustion process in the combustor significantly affects engine performance.In this study,a detailed model for aluminum particle combustion in water vapor is developed and validated via literature data as well as the ground direct-connected test we conducted.Thereafter,the numerical study on the multiphase combustion process inside the aluminum-based PFWRE combustor is carried out within the Euler–Lagrange framework using the developed model.Results show that a reverse rotating vortex pair before the primary water injection causes particles to flow back towards the combustor head and leads to product deposition.Aluminum particles external to the powder jet have shorter preheating time than internal particles and burn out in advance.The analysis of the particle combustion process indicates that the flame structure inside the combustor consists of the particle preheating zone,the surface combustion heat release zone,the gas-phase combustion heat release zone,and the post-flame zone.In the present configuration,as the particle size increases from 10μm to 20μm,the preheating zone length increases from 35 mm to 85 mm.Meanwhile,heat release from gas-phase combustion decreases,and the average temperature of the combustor head first increases and then decreases.This study not only provides insight into the multiphase combustion characteristics of the aluminum-based PFWRE combustor but also offers guidance for the design of the combustion organization schemes and engine structure optimization.
文摘The optimization method of a mathematical model and connected-pipe experimental technique for a test in altitude test facility (ATF) of a liquid fuel ramjet engine was researched.The optimization of the simple mathematical model was divided into two steps.Firstly,using the test engine's geometry configuration size data,a preliminary adjustment was done.Secondly,using experimental test data,the components' experiential coefficients were modified appropriately.Emphasis was laid on the simulation technique of flight condition and parameters measurement method.The experimental technique was applied to a ramjet ATF test successfully.The comparison results show that the optimized-model has higher precision and the nozzle gross thrust difference drops from 12% to about 4%.
基金supported by the National Basic Research Program of China ("973" Program) (Grant No. 61350)
文摘A performance study of a water ramjet engine is described.The engine is powered by the reaction of a magnesium-based propellant and ingested water.In this study,a solid propellant,which consisted of a large percentage of magnesium,a binder and a small amount of oxidant,was used as a hydro reactive fuel.Cold water was injected into the combustion chamber as a main oxidant.A scaled-down experimental engine was tested in a direct-connect ground testing system to characterize the factors influencing the engine performance.The results show that the increasing of total water/fuel ratio,an addition of secondary water intake along the combustion chamber,a larger magnesium content in the solid propellant,a smaller primary water injection angle towards the coming main flow,and a higher primary injection pressure were all able to promote the engine performance.The maximum engine performance was obtained in test 08,and with all tests,an appropriate set of parameters and conditions for the optimum engine performance were determined
文摘The main interest in the current study focuses on the possibility of overspeeding for the gas-generator cycle air turbo ramjet(GG-ATR)engine.The authors developed the air turbo ramjet engine and investigated its compressor performance.Based on those data,the authors developed the analytical code for the air turbo ramjet engine,which calculates the performances of turbomachinery,gas-generator,and ram combustor.The previous study described that the rotor overspeeding would not occur in the air turbo rocket engine.However,the current results show that degraded ram combustion can decrease the compressor pressure ratio and the compressor power.This reduced compressor power can cause overspeeding for the air turbo ramjet engine.The experimental results of compressor power and turbine inlet pressure support those analytical results.
基金supported from support from the National Natural Science Foundation of China(Nos.12441204,12302451 and 1202491)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.CX20210075)。
文摘This study investigates the mixing enhancement mechanism and propagation characteristics of the detonation flow field of a Rotating Detonation Engine(RDE).Three-dimensional numerical simulations of a non-premixed ramjet-based RDE fueled by gaseous ethylene are performed in OpenFOAM for configurations with 15,30,45,and 60 orifices at a flight Mach number of 4.The results show that fuels with a stripped distribution are primarily mixed via tangential diffusion in the cold flow field.The configuration with more orifices has a better upstream mixing efficiency,whereas its downstream mixing efficiency,which is limited by the depth of penetration,is difficult to improve further.Backward Pressure Perturbations(BPPs)opposite to the propagation direction of Rotating Detonation Waves(RDWs)are produced by the reflection of the upstream oblique shock wave with the incoming stream and the hot release of local reactions after RDWs,which significantly affects the propagation mode and mixing.The RDWs propagate in the stable single-wave mode in configurations with 45 or 60 orifices and in the multi-wave mode in configurations with 30 orifices,whereas they fail in configurations with 15 orifices.Compared with that in the cold flow field,deceleration of the main flow,pressurization,and tangential velocity perturbation caused by the RDW substantially enhance the mixing efficiency.Moreover,the tangential velocity perturbations of upstream oblique shock waves and BPPs reduce the unevenness of the fuel distribution for the next cycle.This study reveals the mixing enhancement mechanism of RDWs and can contribute to the design of the injection scheme of the RDE.
基金Project supported by the Young Scientist Fund of the National Natural Science Foundation of China(Grant No.51006118)
文摘We investigate experimentally and analytically the combustion behavior of a high-metal magnesium-based hydro- reactive fuel under high temperature gaseous atmosphere. The fuel studied in this paper contains 73% magnesium powders. An experimental system is designed and experiments are carried out in both argon and water vapor atmo- spheres. It is found that the burning surface temperature of the fuel is higher in water vapor than that in argon and both of them are higher than the melting point of magnesium, which indicates the molten state of magnesium particles in the burning surface of the fuel. Based on physical considerations and experimental results, a mathematical one-dimensional model is formulated to describe the combustion behavior of the high-metal magnesium-based hydro-reactive fuel. The model enables the evaluation of the burning surface temperature, the burning rate and the flame standoff distance each as a function of chamber pressure and water vapor concentration. The results predicted by the model show that the burning rate and the surface temperature increase when the chamber pressure and the water vapor concentration increase, which are in agreement with the observed experimental trends.
