The rapidly developing microsatellites have put forward new requirements of small volume and low power for propulsion systems.The Wall-Less Hall Thruster(WLHT)is proposed as a promising method to help the Hall thruste...The rapidly developing microsatellites have put forward new requirements of small volume and low power for propulsion systems.The Wall-Less Hall Thruster(WLHT)is proposed as a promising method to help the Hall thruster overcome the issues of wall loss and erosion when applied in microsatellites.However,the in-orbit application of WLHTs is hindered by two key issues:large beam divergence and discharge oscillations,which require further research on effective control.In this paper,a novel electromagnetic-controlled wall-less Hall thruster was developed and tested to regulate the propulsion performance including beam divergence angle,and anode oscillations.Experiments show that adjusting the coil current makes it possible to achieve high thrust performance with low anode current oscillations.According to thermalized potential theory,the performance is improved mainly due to changes in the magnetic field near the anode.At the anode voltage of 300 V and volume flow rate of 6 sccm(standard cubic centimeters per minute)using xenon gas as propellant,the electromagnetic control can increase the thrust by 10.4%(5.79 mN vs 6.39 mN)and the anode efficiency by 2.6 percentage points(19.1%vs 21.7%),and reduce the90%plume half-angle by 14.3%(76.1.to 65.2.).In addition,the production of magnetic field via current-carrying coil can suppress the amplitude of anode current oscillations almost without reducing the thrust performance.The breathing oscillation amplitude of the anode current decreases from 37.2%to 2.6%by adjusting the coil current from+3 A to+4 A,while the thrust only decreases by 0.7%(6.39 mN vs 6.35 mN).This is mainly caused by a sudden change in the direction of the magnetic field near the cathode outlet.The performance of the proposed thruster at the anode power of 200 W is comparable to the state-of-the-art low-power wall-less Hall thrusters.展开更多
The current work aims at employing a gradient descent algorithm for optimizing the thrust of a flapping wing. An in-house solver has been employed, along with mesh movement methodologies to capture the dynamics of flo...The current work aims at employing a gradient descent algorithm for optimizing the thrust of a flapping wing. An in-house solver has been employed, along with mesh movement methodologies to capture the dynamics of flow around the airfoil. An efficient framework for implementing the coupled solver and optimization in a multicore environment has been implemented for the generation of optimized solutionsmaximizing thrust performance & computational speed.展开更多
The high-efficiency Shock Vectoring Control Serpentine Nozzle(SVCSN)takes into account both thrust vectoring and infrared stealth,and significantly improves the comprehensive performance of the aero-engines through an...The high-efficiency Shock Vectoring Control Serpentine Nozzle(SVCSN)takes into account both thrust vectoring and infrared stealth,and significantly improves the comprehensive performance of the aero-engines through an additional auxiliary duct.In this paper,the schlieren photographs at the exit of the high-efficiency SVCSN and the wall static pressure distributions were obtained by experiments,and the numerical results were used to enrich the thrust vectoring characteristics.The effects of the auxiliary injection were analyzed first to reveal the advantages of the high-efficiency SVCSN compared to the conventional SVCSN.Then,the aerodynamic parameters and the structural parameters of the high-efficiency SVCSN were investigated,including the Nozzle Pressure Ratio(NPR),the Secondary flow Pressure Ratio(SPR),the secondary flow relative area and the secondary flow injection angle.Finally,the coupling performance of the high-efficiency SVCSN is studied by using the approximate modeling technology.Results show that the auxiliary injection increases the range between the two shock legs of the “k”shock wave induced by the secondary flow,then causes the separation zone and high-pressure boss of the down wall to expand upstream,and finally results in a prominent increase in the thrust vectoring performance.The thrust vectoring angle and Vectoring Efficiency(VE)of the high-efficiency SVCSN are about 61.6%and 75.7%,respectively,higher than those of the conventional SVCSN at NPR=6.The effects of the NPR and the SPR on the thrust vectoring performance of the high-efficiency SVCSN are coupled with each other.A larger NPR matched with a smaller SPR shows better thrust vectoring performance.The maximum fluctuations in thrust vectoring angle and VE caused by the NPR and SPR are about 22%and 64%.The VE decreases monotonously with the increase of the secondary flow relative area.Smaller secondary flow injection angle shows better thrust vector performance,and the thrust vectoring angle and VE of the secondary flow injection angle of 90are about 20%higher than those of the secondary flow injection angle of 110at NPR=6.Therefore,the secondary flow relative area of 0.06 and the secondary flow injection angle of 90are recommended.展开更多
基金supported by the National Natural Science Foundation of China(Nos.523B2078 and 52277133)the Fundamental Research Funds for the Central Universities,China(No.JKF-2025009442288)+1 种基金the Excellent Youth Team Cultivation Project for Central Universities of the Ministry of Education,China(No.YWF-22/23/24-JT-106)the Academic Excellence Foundation of BUAA for PhD students,China。
文摘The rapidly developing microsatellites have put forward new requirements of small volume and low power for propulsion systems.The Wall-Less Hall Thruster(WLHT)is proposed as a promising method to help the Hall thruster overcome the issues of wall loss and erosion when applied in microsatellites.However,the in-orbit application of WLHTs is hindered by two key issues:large beam divergence and discharge oscillations,which require further research on effective control.In this paper,a novel electromagnetic-controlled wall-less Hall thruster was developed and tested to regulate the propulsion performance including beam divergence angle,and anode oscillations.Experiments show that adjusting the coil current makes it possible to achieve high thrust performance with low anode current oscillations.According to thermalized potential theory,the performance is improved mainly due to changes in the magnetic field near the anode.At the anode voltage of 300 V and volume flow rate of 6 sccm(standard cubic centimeters per minute)using xenon gas as propellant,the electromagnetic control can increase the thrust by 10.4%(5.79 mN vs 6.39 mN)and the anode efficiency by 2.6 percentage points(19.1%vs 21.7%),and reduce the90%plume half-angle by 14.3%(76.1.to 65.2.).In addition,the production of magnetic field via current-carrying coil can suppress the amplitude of anode current oscillations almost without reducing the thrust performance.The breathing oscillation amplitude of the anode current decreases from 37.2%to 2.6%by adjusting the coil current from+3 A to+4 A,while the thrust only decreases by 0.7%(6.39 mN vs 6.35 mN).This is mainly caused by a sudden change in the direction of the magnetic field near the cathode outlet.The performance of the proposed thruster at the anode power of 200 W is comparable to the state-of-the-art low-power wall-less Hall thrusters.
文摘The current work aims at employing a gradient descent algorithm for optimizing the thrust of a flapping wing. An in-house solver has been employed, along with mesh movement methodologies to capture the dynamics of flow around the airfoil. An efficient framework for implementing the coupled solver and optimization in a multicore environment has been implemented for the generation of optimized solutionsmaximizing thrust performance & computational speed.
基金supported by the Science Center for Gas Turbine Project,China(Nos.P2022-B-Ⅱ-010-001 and P2022-B-I-002-001)the National Natural Science Foundation of China(Nos.52376032 and 52076180)+2 种基金the Funds for Distinguished Young Scholars of Shaanxi Province,China(No.2021JC-10)the National Science and Technology Major Project,China(No.J2019-Ⅱ-0015-0036)the Fundamental Research Funds for the Central Universities,China(No.501XTCX2023146001).
文摘The high-efficiency Shock Vectoring Control Serpentine Nozzle(SVCSN)takes into account both thrust vectoring and infrared stealth,and significantly improves the comprehensive performance of the aero-engines through an additional auxiliary duct.In this paper,the schlieren photographs at the exit of the high-efficiency SVCSN and the wall static pressure distributions were obtained by experiments,and the numerical results were used to enrich the thrust vectoring characteristics.The effects of the auxiliary injection were analyzed first to reveal the advantages of the high-efficiency SVCSN compared to the conventional SVCSN.Then,the aerodynamic parameters and the structural parameters of the high-efficiency SVCSN were investigated,including the Nozzle Pressure Ratio(NPR),the Secondary flow Pressure Ratio(SPR),the secondary flow relative area and the secondary flow injection angle.Finally,the coupling performance of the high-efficiency SVCSN is studied by using the approximate modeling technology.Results show that the auxiliary injection increases the range between the two shock legs of the “k”shock wave induced by the secondary flow,then causes the separation zone and high-pressure boss of the down wall to expand upstream,and finally results in a prominent increase in the thrust vectoring performance.The thrust vectoring angle and Vectoring Efficiency(VE)of the high-efficiency SVCSN are about 61.6%and 75.7%,respectively,higher than those of the conventional SVCSN at NPR=6.The effects of the NPR and the SPR on the thrust vectoring performance of the high-efficiency SVCSN are coupled with each other.A larger NPR matched with a smaller SPR shows better thrust vectoring performance.The maximum fluctuations in thrust vectoring angle and VE caused by the NPR and SPR are about 22%and 64%.The VE decreases monotonously with the increase of the secondary flow relative area.Smaller secondary flow injection angle shows better thrust vector performance,and the thrust vectoring angle and VE of the secondary flow injection angle of 90are about 20%higher than those of the secondary flow injection angle of 110at NPR=6.Therefore,the secondary flow relative area of 0.06 and the secondary flow injection angle of 90are recommended.
