Powder engine as a novel type of engine using high-energy metal powder as fuel and gas,liquid,or solid as oxidizer.These engines exhibit remarkable adaptability,flexible thrust regulation,and multi-pulse start-stop,wh...Powder engine as a novel type of engine using high-energy metal powder as fuel and gas,liquid,or solid as oxidizer.These engines exhibit remarkable adaptability,flexible thrust regulation,and multi-pulse start-stop,which have significant application potentials in the fields of near-Earth space development,space propulsion systems,and deep-sea exploration.The scope of this review encompasses the classification and application of powder engines,the classification of powdered fuel supply systems,and the prospective trajectories and pivotal challenges of powder engines and fuel supply technologies.This work points out that although certain ground-based experimental challenges on powder engines have been solved,the relative technology remains in the nascent stages of feasibility demonstration and testing.The pneumatic and motor-driven piston methods currently dominate as the primary means for supplying fuel,and the structure of the piston and intake should be further optimized in the future to promote fuel fluidization and delivery efficiency.The adaptability of powder engines and powdered fuels under different pre-treatment and loading methods should be evaluated.Furthermore,the stability of powdered fuel delivery across varying operational environments,the accuracy of CFD modeling,and the precision of mass flow rate measurement and prediction technologies necessitate further enhancement and refinement.These advancements are crucial for the maturation of powder engine technology and its integration into practical applications.展开更多
The fuel delivery laws of horizontal tanks are no longer adequate for efficient supply under complex flight conditions,while the supply characteristics of non-horizontal tanks are not sufficiently explored.In this wor...The fuel delivery laws of horizontal tanks are no longer adequate for efficient supply under complex flight conditions,while the supply characteristics of non-horizontal tanks are not sufficiently explored.In this work,the piston-driven fuel supply devices with external slit-shaped and novel built-in cube-,sphere-,and dome-shaped intakes were selected as the research objects.The conveying sensitivity of devices at different tilt angles was investigated using two-fluid model.The results indicate that as the tilt angle increases from 0◦to 90◦,the fluctuation in mass flow rate of powder under the cube-,sphere-,and dome-shaped intakes increases by about 53.8%,46.6%,and 35.0%,respectively,while the slit-shaped intake decreases by about 1.0%.The gas under the built-in intake migrates from the head of the device to the outlet,while the gas under the external intake is distributed near the wall of the conical convergence section,and the fluctuations in pressure and relative pressure drop of the former are more intense than those of the latter.At varying tilt angles,the area of gas phase under external intake is approximately 15 times that of the built-in.At low tilt angles(0◦and 30◦),the variations in gas-solid velocities and powder concentration are similar for the domeand slit-shaped intakes.As the tilt angle increases,the fluctuation in these two physical quantities in the cubeand sphere-shaped intakes is larger than in other cases.At a high tilt angle(90◦),the built-in cube-shaped intake exhibits the least satisfactory supply performance.展开更多
A novel powder metallurgy （P/M） material with high wear resistance is developed in order to decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests of this material are co...A novel powder metallurgy （P/M） material with high wear resistance is developed in order to decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests of this material are conducted. It indicates that the wear resistance of the newly developed P/M material has been improved and much better than that of the formerly used alloy steel. Moreover, three different sealing structures are designed and theoretically analyzed with respect to the characteristic of hydrodynamic sealing. Through comparative experiments of component leakage and engine run-in for different valve guide structures, it proves that the structure with a machined sealing groove but not installed with a seal-ring cannot only reduce the specific lubricant consumption （SLC） of cylinder head, but also decrease the wear of valve stern and valve guide.展开更多
基金supported by the National Natural Science Foundation of China(grant number:12102161)the Key Research and Development Program of Jiangxi Province,China(grant number:20232BBE50005)the Natural Science Foundation of Jiangxi Province,China(grant number:20224BAB214060)。
文摘Powder engine as a novel type of engine using high-energy metal powder as fuel and gas,liquid,or solid as oxidizer.These engines exhibit remarkable adaptability,flexible thrust regulation,and multi-pulse start-stop,which have significant application potentials in the fields of near-Earth space development,space propulsion systems,and deep-sea exploration.The scope of this review encompasses the classification and application of powder engines,the classification of powdered fuel supply systems,and the prospective trajectories and pivotal challenges of powder engines and fuel supply technologies.This work points out that although certain ground-based experimental challenges on powder engines have been solved,the relative technology remains in the nascent stages of feasibility demonstration and testing.The pneumatic and motor-driven piston methods currently dominate as the primary means for supplying fuel,and the structure of the piston and intake should be further optimized in the future to promote fuel fluidization and delivery efficiency.The adaptability of powder engines and powdered fuels under different pre-treatment and loading methods should be evaluated.Furthermore,the stability of powdered fuel delivery across varying operational environments,the accuracy of CFD modeling,and the precision of mass flow rate measurement and prediction technologies necessitate further enhancement and refinement.These advancements are crucial for the maturation of powder engine technology and its integration into practical applications.
基金supported by the National Natural Science Foundation of China(grant No.12102161)the Key Research Program of Jiangxi Province,China(grant No.20232BBE50005)the Natural Science Foundation of Jiangxi Province,China(grant No.20224BAB214060).
文摘The fuel delivery laws of horizontal tanks are no longer adequate for efficient supply under complex flight conditions,while the supply characteristics of non-horizontal tanks are not sufficiently explored.In this work,the piston-driven fuel supply devices with external slit-shaped and novel built-in cube-,sphere-,and dome-shaped intakes were selected as the research objects.The conveying sensitivity of devices at different tilt angles was investigated using two-fluid model.The results indicate that as the tilt angle increases from 0◦to 90◦,the fluctuation in mass flow rate of powder under the cube-,sphere-,and dome-shaped intakes increases by about 53.8%,46.6%,and 35.0%,respectively,while the slit-shaped intake decreases by about 1.0%.The gas under the built-in intake migrates from the head of the device to the outlet,while the gas under the external intake is distributed near the wall of the conical convergence section,and the fluctuations in pressure and relative pressure drop of the former are more intense than those of the latter.At varying tilt angles,the area of gas phase under external intake is approximately 15 times that of the built-in.At low tilt angles(0◦and 30◦),the variations in gas-solid velocities and powder concentration are similar for the domeand slit-shaped intakes.As the tilt angle increases,the fluctuation in these two physical quantities in the cubeand sphere-shaped intakes is larger than in other cases.At a high tilt angle(90◦),the built-in cube-shaped intake exhibits the least satisfactory supply performance.
基金This project is supported by National Natural Science Foundation ofChina(No.50135020), Key Science and Technology Research Project ofMinistry of Education, China (No.0203) and Provincial Science and Tech-nology Plan of Guangdong, China (No.2004B10301018).
文摘A novel powder metallurgy （P/M） material with high wear resistance is developed in order to decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests of this material are conducted. It indicates that the wear resistance of the newly developed P/M material has been improved and much better than that of the formerly used alloy steel. Moreover, three different sealing structures are designed and theoretically analyzed with respect to the characteristic of hydrodynamic sealing. Through comparative experiments of component leakage and engine run-in for different valve guide structures, it proves that the structure with a machined sealing groove but not installed with a seal-ring cannot only reduce the specific lubricant consumption （SLC） of cylinder head, but also decrease the wear of valve stern and valve guide.
