The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability,...The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability, low vapor pressure, and ionization potential. The performance of a lowpower iodine-fed Hall thruster matched with a xenon-fed cathode is investigated across a broad range of operation conditions. Regulation of the iodine vapor's mass flow rates is stably achieved by using a temperature control method of the iodine reservoir. The thrust measurements are finished utilizing a thrust target during the tests. Results show that thrust and anode-specific impulse increase approximately linearly with the increasing iodine mass flow rate.At the nominal power of 200 W class, iodine mass flow rates are 0.62 and 0.93 mg/s, thrusts are7.19 and 7.58 m N, anode specific impulses are 1184 and 826 s, anode efficiencies are 20.8%and 14.5%, and thrust to power ratios are 35.9 and 37.9 m N/k W under the conditions of 250 V,0.8 A and 200 V, 1.0 A, respectively. The operating characteristics of iodine-fed Hall thruster are analyzed in different states. Further work on the measurements of plasma characteristics and experimental optimization will be carried out.展开更多
The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, su...The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, supersonic and arc-heated jets are explored, and factors affecting the accuracy of the method are studied and discussed. Results show that the impulse method is reliable for indirect thrust measurement if certain basic requirements are met, and a simple guideline for its proper application is given.展开更多
The applications of the micro-thrust e r and the challenges of micro-thrust measuring are introduced.The developments in measuring techniques for the micro-thrust are reviewed.Micro-thrust measu rements have previousl...The applications of the micro-thrust e r and the challenges of micro-thrust measuring are introduced.The developments in measuring techniques for the micro-thrust are reviewed.Micro-thrust measu rements have previously been made either directly by mounting thrusters to the m easurement system or indirectly by mounting a target in the direct path of the e jected propellant.Several typical direct and indirect thrust-stands are presen ted and discussed in detail to illustrate the principles.Typical calibration me thods are also expounded.Finally,the resolution,uncertainty and thrust range of each thrust-stand are given,which may be helpful for the future thrust stan d design and micro-thrusters research.展开更多
In this work, a three-dimensional （3D） Computational Fluid Dynamics （CFD） model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum...In this work, a three-dimensional （3D） Computational Fluid Dynamics （CFD） model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum thrust tail-beat frequency. A simulation of the tail fin at a tail-beat frequency was performed to confirm measured thrust data from a previous study. The computed and measured thrusts were in good agreement. A series of thrust simulations were conducted for various tail-beat frequencies to confirm the maximum thrust frequency that was obtained from thrust measurements in the previous study. The largest thrust was calculated at a tail-beat frequency of 3.7 Hz and vortices around the tail were fully separated. The calculated maximum thrust tail-beat frequency was in good agreement with the measured frequency. Flow characteristics during tail fin motion were examined to explain why the largest thrust occurred at this particular tail-beat frequency.展开更多
In order to test the feasibility of a new thrust stand system based on impulse thrust mea- surement method, a liquid-fueled pulse detonation engine （PDE） is designed and built. Thrust per- formance of the engine is ...In order to test the feasibility of a new thrust stand system based on impulse thrust mea- surement method, a liquid-fueled pulse detonation engine （PDE） is designed and built. Thrust per- formance of the engine is obtained by direct thrust measurement with a force transducer and indirect thrust measurement with an eddy current displacement sensor （ECDS）. These two sets of thrust data are compared with each other to verify the accuracy of the thrust performance. Then thrust data measured by the new thrust stand system are compared with the verified thrust data to test its feasibility. The results indicate that thrust data from the force transducer and ECDS system are consistent with each other within the range of measurement error. Though the thrust data from the impulse thrust measurement system is a litter lower than that from the force transducer due to the axial momentum losses of the detonation jet, the impulse thrust measurement method is valid when applied to measure the averaged thrust of PDE. Analytical models of PDE are also discussed in this paper. The analytical thrust performance is higher than the experimental data due to ignoring the losses during the deflagration to detonation transition process. Effect of equivalence ratio on the engine thrust performance is investigated by utilizing the modified analytical model. Thrust reaches maximum at the equivalence ratio of about 1.1.展开更多
In this paper, we theoretically predict and experimentally measure the thrust efficiency of a biomimetic robotic fish, which is propelled by an ionic polymer-metal composite （IPMC） actuator. A physics-based model th...In this paper, we theoretically predict and experimentally measure the thrust efficiency of a biomimetic robotic fish, which is propelled by an ionic polymer-metal composite （IPMC） actuator. A physics-based model that consists of IPMC dynamics and hydrodynamics was proposed, and simulation was conducted. In order to test the thrust performance of the robotic fish, a novel experimental apparatus was developed for hydrodynamic experiments. Under a servo towing system, the IPMC fish swam at a self-propelled speed where external force is averagely zero. Experimental results demonstrated that the theoretical model can well predict the thrust efficiency of the robotic fish. A maximum thrust efficiency of 2.3x10-3 at 1 Hz was recorded experi- mentally, the maximum thrust force was 0.0253 N, recorded at 1.2 Hz, while the maximum speed was 0.021 m/s, recorded at 1.5 Hz, and a peak power of 0.36 W was recorded at 2.6 Hz. Additionally, the optimal actuation frequency for the thrust efficiency was also recorded at the maximum self-propelled speed. The present method of examining the thrust efficiency may also be applied to the studies of other types of smart material actuated underwater robots.展开更多
基金supported by Joint Fund for Equipment Preresearch and Aerospace Science and Technology (No. 6141B061203)。
文摘The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability, low vapor pressure, and ionization potential. The performance of a lowpower iodine-fed Hall thruster matched with a xenon-fed cathode is investigated across a broad range of operation conditions. Regulation of the iodine vapor's mass flow rates is stably achieved by using a temperature control method of the iodine reservoir. The thrust measurements are finished utilizing a thrust target during the tests. Results show that thrust and anode-specific impulse increase approximately linearly with the increasing iodine mass flow rate.At the nominal power of 200 W class, iodine mass flow rates are 0.62 and 0.93 mg/s, thrusts are7.19 and 7.58 m N, anode specific impulses are 1184 and 826 s, anode efficiencies are 20.8%and 14.5%, and thrust to power ratios are 35.9 and 37.9 m N/k W under the conditions of 250 V,0.8 A and 200 V, 1.0 A, respectively. The operating characteristics of iodine-fed Hall thruster are analyzed in different states. Further work on the measurements of plasma characteristics and experimental optimization will be carried out.
基金supported by the National Natural Science Foundation of China (50836007, 10921062, 10772016)
文摘The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, supersonic and arc-heated jets are explored, and factors affecting the accuracy of the method are studied and discussed. Results show that the impulse method is reliable for indirect thrust measurement if certain basic requirements are met, and a simple guideline for its proper application is given.
基金National Natural Science Foundation of China (No.91216201, No.51205403)
文摘The applications of the micro-thrust e r and the challenges of micro-thrust measuring are introduced.The developments in measuring techniques for the micro-thrust are reviewed.Micro-thrust measu rements have previously been made either directly by mounting thrusters to the m easurement system or indirectly by mounting a target in the direct path of the e jected propellant.Several typical direct and indirect thrust-stands are presen ted and discussed in detail to illustrate the principles.Typical calibration me thods are also expounded.Finally,the resolution,uncertainty and thrust range of each thrust-stand are given,which may be helpful for the future thrust stan d design and micro-thrusters research.
文摘In this work, a three-dimensional （3D） Computational Fluid Dynamics （CFD） model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum thrust tail-beat frequency. A simulation of the tail fin at a tail-beat frequency was performed to confirm measured thrust data from a previous study. The computed and measured thrusts were in good agreement. A series of thrust simulations were conducted for various tail-beat frequencies to confirm the maximum thrust frequency that was obtained from thrust measurements in the previous study. The largest thrust was calculated at a tail-beat frequency of 3.7 Hz and vortices around the tail were fully separated. The calculated maximum thrust tail-beat frequency was in good agreement with the measured frequency. Flow characteristics during tail fin motion were examined to explain why the largest thrust occurred at this particular tail-beat frequency.
基金supported by the National Natural Science Foundation of China (No. 51306153)the Natural Science Foundation of Shanxi Province of China (No. 2010JQ7005)+1 种基金Doctoral Fund of Ministry of Education of China (No. 20116102120027)Northwestern Polytechnical University Foundation for Fundamental Research (No. NPU-FFRJCY20130129)
文摘In order to test the feasibility of a new thrust stand system based on impulse thrust mea- surement method, a liquid-fueled pulse detonation engine （PDE） is designed and built. Thrust per- formance of the engine is obtained by direct thrust measurement with a force transducer and indirect thrust measurement with an eddy current displacement sensor （ECDS）. These two sets of thrust data are compared with each other to verify the accuracy of the thrust performance. Then thrust data measured by the new thrust stand system are compared with the verified thrust data to test its feasibility. The results indicate that thrust data from the force transducer and ECDS system are consistent with each other within the range of measurement error. Though the thrust data from the impulse thrust measurement system is a litter lower than that from the force transducer due to the axial momentum losses of the detonation jet, the impulse thrust measurement method is valid when applied to measure the averaged thrust of PDE. Analytical models of PDE are also discussed in this paper. The analytical thrust performance is higher than the experimental data due to ignoring the losses during the deflagration to detonation transition process. Effect of equivalence ratio on the engine thrust performance is investigated by utilizing the modified analytical model. Thrust reaches maximum at the equivalence ratio of about 1.1.
基金supported by the National Natural Science Foundation of China (Grant No. 61075100)
文摘In this paper, we theoretically predict and experimentally measure the thrust efficiency of a biomimetic robotic fish, which is propelled by an ionic polymer-metal composite （IPMC） actuator. A physics-based model that consists of IPMC dynamics and hydrodynamics was proposed, and simulation was conducted. In order to test the thrust performance of the robotic fish, a novel experimental apparatus was developed for hydrodynamic experiments. Under a servo towing system, the IPMC fish swam at a self-propelled speed where external force is averagely zero. Experimental results demonstrated that the theoretical model can well predict the thrust efficiency of the robotic fish. A maximum thrust efficiency of 2.3x10-3 at 1 Hz was recorded experi- mentally, the maximum thrust force was 0.0253 N, recorded at 1.2 Hz, while the maximum speed was 0.021 m/s, recorded at 1.5 Hz, and a peak power of 0.36 W was recorded at 2.6 Hz. Additionally, the optimal actuation frequency for the thrust efficiency was also recorded at the maximum self-propelled speed. The present method of examining the thrust efficiency may also be applied to the studies of other types of smart material actuated underwater robots.
