The accurate parameters measurement of the flow field between the stages for axial compressors is a significant demand.This paper proposes an axial compressor inter-stage flow field high-precision test system,which ma...The accurate parameters measurement of the flow field between the stages for axial compressors is a significant demand.This paper proposes an axial compressor inter-stage flow field high-precision test system,which mainly consists of a probe motion scanning mechanism,fully automated test control software,and data processing methods.Iterative correction is applied to the original readings obtained from the scanning tests to enhance testing accuracy.Using this test system,detailed tests are conducted on a 1.5-stage subsonic axial compressor under different operating conditions.The test results effectively captured the impact of surface roughness and tip clearance variations on compressor performance.The distribution characteristics of parameters measured in inter-stage sections can characterize the effects of blade wake area and changes in aerodynamic performance at different blade heights.The developed test system can be extended to multi-stage compressors.展开更多
According to the physical and chemical characteristics of superfine powder extinguishing agent,three test methods are selected to measure the flow ability.By studying and comparing various test methods,apparatus and c...According to the physical and chemical characteristics of superfine powder extinguishing agent,three test methods are selected to measure the flow ability.By studying and comparing various test methods,apparatus and conditions,the optimum method and conditions to test flow property of superfine powder extinguishing agent are confirmed.展开更多
In order to understand the dynamics of granular flow on an erodible base soil,in this paper,a series of material point method-based granular column collapse tests were conducted to investigate numerically the mobility...In order to understand the dynamics of granular flow on an erodible base soil,in this paper,a series of material point method-based granular column collapse tests were conducted to investigate numerically the mobility and dynamic erosion process of granular flow subjected to the complex settings,i.e.,the aspect ratio,granular mass,friction and dilatancy resistance,gravity and presence of water.A set of power scaling laws were proposed to describe the final deposit characteristics of granular flow by the relations of the normalized run-out distance and the normalized final height of granular flow against the aspect ratio,being greatly affected by the complex geological settings,e.g.,granular mass,the friction and dilatancy resistance of granular soil,and presence of water in granular flow.An index of the coefficient of friction of granular soil was defined as a ratio of the target coefficient of friction over the initial coefficient of friction to quantify the scaling extent of friction change(i.e.,friction strengthening or weakening).There is a characteristic aspect ratio of granular column corresponding to the maximum mobility of granular flow with the minimum index of the apparent coefficient of friction.The index of the repose coefficient of friction of granular flow decreased gradually with the increase in aspect ratio because higher potential energy of granular column at a larger aspect ratio causes a larger kinetic energy of granular soil to weaken the friction of granular soil as a kind of velocity-related friction weakening.An increase in granular mass reduces gradually the indexes of the apparent and repose coefficients of friction of granular soil to enhance the mobility of granular flow.The mobility of granular flow increases gradually with the decrease in friction angle or increase in dilatancy angle of granular soil.However,the increase of gravity accelerates granular flow but showing the same final deposit profile without any dependence on gravity.The mobility of granular flow increases gradually by lowering the indexes of the apparent and repose coefficients of friction of granular flow while changing the surroundings,in turn,the dry soil,submerged soil and saturated soil,implying a gradually increased excessive mobility of granular flow with the friction weakening of granular soil.Presence of water in granular flow may be a potential catalyzer to yield a long run-out granular flow,as revealed in comparison of water-absent and water-present granular flows.In addition,the dynamic erosion and entrainment of based soil induced by granular flow subjected to the complex geological settings,i.e.,the aspect ratio,granular mass,gravity,friction and dilatancy resistance,and presence of water,were comprehensively investigated as well.展开更多
Against the background of the sand-flow foundation treatment engineering of Guangzhou Zhoutouzui variable cross-section immersed tunnel, a kind of sand deposit-detecting method was devised on the basis of full-scale m...Against the background of the sand-flow foundation treatment engineering of Guangzhou Zhoutouzui variable cross-section immersed tunnel, a kind of sand deposit-detecting method was devised on the basis of full-scale model test of sand-flow method. The real-time data of sand-deposit height and radius were obtained by the self-developed sand-deposit detectors. The test results show that the detecting method is simple and has high precision. In the use of sand-flow method, the sand-carrying capability of fluid is limited, and sand particles are all transported to the sand-deposit periphery through crater, gap and chutes after the sand deposit formed. The diffusion range of the particles outside the sand-deposit does not exceed 2.0 m. Severe sorting of sand particles is not observed because of the unique oblique-layered depositing process. The temporal and spatial distributions of gap and chutes directly affect the sand-deposit expansion, and the expansion trend of the average sand-deposit radius accords with quadratic time-history curve.展开更多
In order to advance the understanding of the impact dynamics of granular flow in complex geological settings,this paper studied the impact dynamics of granular flow on rigid barriers with a number of Material Point Me...In order to advance the understanding of the impact dynamics of granular flow in complex geological settings,this paper studied the impact dynamics of granular flow on rigid barriers with a number of Material Point Method(MPM)numerical tests.The impact behavior of granular flow on a rigid barrier was characterized by the initial dynamic impact stage,dynamic surge impact stage,compression impact stage and static stage of granular flow,where the impact force of granular flow was comprised of the dynamic and static forces of granular flow.The impact behavior of granular flow on a rigid barrier was characterized by the states of the fast or slow impact behavior of granular flow.The angle of slope and aspect ratio of granular soil greatly affected the impact behavior of granular flow on a column rigid barrier,where a power model was proposed to quantify the residual(Fnr)-over-maximum(Fnmax)normal impact force ratio of granular flow Fnr⁄Fnmax incorporating the effects of the angle of slope and aspect ratio of granular soil.With the increase of the column rigid barrier up to the semi-infinite column rigid barrier,the impact dynamics of granular flow gradually increased up to a maximum by progressively transforming the overflow into the dynamic surge impact of the incoming flow on the rigid barrier to capture more granular soil of granular flow against the rigid barrier.Presence of water in granular flow,i.e.,a mixture of solid and liquid in granular flow,yielded a dynamic coupling contribution of the solid and liquid,being accompanied by the whole dynamic process of granular flow,on the impact behavior of granular flow on a rigid barrier,where the liquid-phase material of granular flow,i.e.,the water,was predominant to contribute on the normal impact force of granular flow in comparison with the solid-phase material of granular flow.In addition,other factors,e.g.,the shape of rigid barrier(i.e.,the column barrier,arch barrier and circle barrier),and the gravity(i.e.,in the gravitational environment of the Moon,Earth and Mars),greatly affected the impact behavior of granular flow on a rigid barrier as well.展开更多
微结构探测器是目前国际上气体探测器研究的热点,但普通微结构探测器的性能无法满足核保障等研究领域对能量分辨的要求。为此团队自主研制了一种高能量分辨MicroMegas探测器。通过建立测试系统对探测器进行测试,发现其性能不仅取决于探...微结构探测器是目前国际上气体探测器研究的热点,但普通微结构探测器的性能无法满足核保障等研究领域对能量分辨的要求。为此团队自主研制了一种高能量分辨MicroMegas探测器。通过建立测试系统对探测器进行测试,发现其性能不仅取决于探测器本身的制作工艺,还与系统的使用及测试方法紧密相关。为充分发挥探测器性能,需要对气体探测器性能影响的各方面因素进行测试与分析,建立数据库,优化测试系统和实验条件。在上述研究基础上,利用^(55)Fe放射源在Ar+5%iC_4H_(10)的气体下对原子能院制作的MicroMegas进行能量分辨测试,在5.9 ke V能量下获得能量分辨的平均值为11.7%,与目前国际上微结构探测器的最好水平持平。通过优化测试系统和实验条件,能够获得更加稳定的探测器性能,更容易在核保障、核物理与辐射探测领域推广。展开更多
The serpentine convergent-divergent nozzle represents an optimal configuration for nextgeneration fighter aircraft characterized by low detectability and high thrust-to-weight ratio.In contrast to the serpentine conve...The serpentine convergent-divergent nozzle represents an optimal configuration for nextgeneration fighter aircraft characterized by low detectability and high thrust-to-weight ratio.In contrast to the serpentine convergent nozzle,such configuration offers increased design flexibility with additional parameters,leading to heightened interactions among these parameters.As such,it is crucial to reveal the influence of design parameters on the aerodynamic performance of the serpentine convergent-divergent nozzle and the multifactor interaction,as well as its mechanism.Therefore,the influence,interaction and sensitivity of parameters on the aerodynamic performance of the nozzle were numerically investigated using the orthogonal test method.Additionally,the influence mechanism of the convergence angle,throat aspect ratio,and axial length to inlet diameter on the flow characteristics of the nozzle was investigated in detail.The results show that the convergence angle is identified as the main factor affecting the aerodynamic parameters of the nozzle.As the convergence angle increases,the thrust coefficient,total pressure recovery coefficient and discharge coefficient gradually decrease.The interaction between throat aspect ratio and other parameters is obvious.Different design parameters affect the local loss and the friction loss by affecting the curvature and wetted perimeter area,resulting in different aerodynamic characteristics of serpentine convergent-divergent nozzle.展开更多
基金National Science and Technology Major Project of China No.2017-V-0012-0064。
文摘The accurate parameters measurement of the flow field between the stages for axial compressors is a significant demand.This paper proposes an axial compressor inter-stage flow field high-precision test system,which mainly consists of a probe motion scanning mechanism,fully automated test control software,and data processing methods.Iterative correction is applied to the original readings obtained from the scanning tests to enhance testing accuracy.Using this test system,detailed tests are conducted on a 1.5-stage subsonic axial compressor under different operating conditions.The test results effectively captured the impact of surface roughness and tip clearance variations on compressor performance.The distribution characteristics of parameters measured in inter-stage sections can characterize the effects of blade wake area and changes in aerodynamic performance at different blade heights.The developed test system can be extended to multi-stage compressors.
文摘According to the physical and chemical characteristics of superfine powder extinguishing agent,three test methods are selected to measure the flow ability.By studying and comparing various test methods,apparatus and conditions,the optimum method and conditions to test flow property of superfine powder extinguishing agent are confirmed.
基金This work was supported by the National Natural Science Foundation of China(Grant no.U22A20603)Sichuan Science and Technology Program-China(Grant No.2023ZYD0149)CAS"Light of West China"Program-China(Grant No.Fangwei Yu).In addition,a special acknowledgement should be expressed to a famous Chinese television drama:My Chief and My Regiment that accompanied me(Dr.Fangwei Yu)through the loneliness time of completing this study.
文摘In order to understand the dynamics of granular flow on an erodible base soil,in this paper,a series of material point method-based granular column collapse tests were conducted to investigate numerically the mobility and dynamic erosion process of granular flow subjected to the complex settings,i.e.,the aspect ratio,granular mass,friction and dilatancy resistance,gravity and presence of water.A set of power scaling laws were proposed to describe the final deposit characteristics of granular flow by the relations of the normalized run-out distance and the normalized final height of granular flow against the aspect ratio,being greatly affected by the complex geological settings,e.g.,granular mass,the friction and dilatancy resistance of granular soil,and presence of water in granular flow.An index of the coefficient of friction of granular soil was defined as a ratio of the target coefficient of friction over the initial coefficient of friction to quantify the scaling extent of friction change(i.e.,friction strengthening or weakening).There is a characteristic aspect ratio of granular column corresponding to the maximum mobility of granular flow with the minimum index of the apparent coefficient of friction.The index of the repose coefficient of friction of granular flow decreased gradually with the increase in aspect ratio because higher potential energy of granular column at a larger aspect ratio causes a larger kinetic energy of granular soil to weaken the friction of granular soil as a kind of velocity-related friction weakening.An increase in granular mass reduces gradually the indexes of the apparent and repose coefficients of friction of granular soil to enhance the mobility of granular flow.The mobility of granular flow increases gradually with the decrease in friction angle or increase in dilatancy angle of granular soil.However,the increase of gravity accelerates granular flow but showing the same final deposit profile without any dependence on gravity.The mobility of granular flow increases gradually by lowering the indexes of the apparent and repose coefficients of friction of granular flow while changing the surroundings,in turn,the dry soil,submerged soil and saturated soil,implying a gradually increased excessive mobility of granular flow with the friction weakening of granular soil.Presence of water in granular flow may be a potential catalyzer to yield a long run-out granular flow,as revealed in comparison of water-absent and water-present granular flows.In addition,the dynamic erosion and entrainment of based soil induced by granular flow subjected to the complex geological settings,i.e.,the aspect ratio,granular mass,gravity,friction and dilatancy resistance,and presence of water,were comprehensively investigated as well.
基金Project(51108190) supported by the National Natural Science Foundation of ChinaProject(2012ZC27) supported by the Independence Research Subject from State Key Laboratory of Subtropical Building Science,ChinaProject(GTCC 2008-253) supported by the Research Subject from Guangzhou City,China
文摘Against the background of the sand-flow foundation treatment engineering of Guangzhou Zhoutouzui variable cross-section immersed tunnel, a kind of sand deposit-detecting method was devised on the basis of full-scale model test of sand-flow method. The real-time data of sand-deposit height and radius were obtained by the self-developed sand-deposit detectors. The test results show that the detecting method is simple and has high precision. In the use of sand-flow method, the sand-carrying capability of fluid is limited, and sand particles are all transported to the sand-deposit periphery through crater, gap and chutes after the sand deposit formed. The diffusion range of the particles outside the sand-deposit does not exceed 2.0 m. Severe sorting of sand particles is not observed because of the unique oblique-layered depositing process. The temporal and spatial distributions of gap and chutes directly affect the sand-deposit expansion, and the expansion trend of the average sand-deposit radius accords with quadratic time-history curve.
基金supported by the Sichuan Science and Technology Program - China (Grant no. 2023ZYD0149)National Natural Science Foundation of China (Grant no. U22A20603)CAS "Light of West China" Program - China (Grant No. Fangwei Yu)
文摘In order to advance the understanding of the impact dynamics of granular flow in complex geological settings,this paper studied the impact dynamics of granular flow on rigid barriers with a number of Material Point Method(MPM)numerical tests.The impact behavior of granular flow on a rigid barrier was characterized by the initial dynamic impact stage,dynamic surge impact stage,compression impact stage and static stage of granular flow,where the impact force of granular flow was comprised of the dynamic and static forces of granular flow.The impact behavior of granular flow on a rigid barrier was characterized by the states of the fast or slow impact behavior of granular flow.The angle of slope and aspect ratio of granular soil greatly affected the impact behavior of granular flow on a column rigid barrier,where a power model was proposed to quantify the residual(Fnr)-over-maximum(Fnmax)normal impact force ratio of granular flow Fnr⁄Fnmax incorporating the effects of the angle of slope and aspect ratio of granular soil.With the increase of the column rigid barrier up to the semi-infinite column rigid barrier,the impact dynamics of granular flow gradually increased up to a maximum by progressively transforming the overflow into the dynamic surge impact of the incoming flow on the rigid barrier to capture more granular soil of granular flow against the rigid barrier.Presence of water in granular flow,i.e.,a mixture of solid and liquid in granular flow,yielded a dynamic coupling contribution of the solid and liquid,being accompanied by the whole dynamic process of granular flow,on the impact behavior of granular flow on a rigid barrier,where the liquid-phase material of granular flow,i.e.,the water,was predominant to contribute on the normal impact force of granular flow in comparison with the solid-phase material of granular flow.In addition,other factors,e.g.,the shape of rigid barrier(i.e.,the column barrier,arch barrier and circle barrier),and the gravity(i.e.,in the gravitational environment of the Moon,Earth and Mars),greatly affected the impact behavior of granular flow on a rigid barrier as well.
文摘微结构探测器是目前国际上气体探测器研究的热点,但普通微结构探测器的性能无法满足核保障等研究领域对能量分辨的要求。为此团队自主研制了一种高能量分辨MicroMegas探测器。通过建立测试系统对探测器进行测试,发现其性能不仅取决于探测器本身的制作工艺,还与系统的使用及测试方法紧密相关。为充分发挥探测器性能,需要对气体探测器性能影响的各方面因素进行测试与分析,建立数据库,优化测试系统和实验条件。在上述研究基础上,利用^(55)Fe放射源在Ar+5%iC_4H_(10)的气体下对原子能院制作的MicroMegas进行能量分辨测试,在5.9 ke V能量下获得能量分辨的平均值为11.7%,与目前国际上微结构探测器的最好水平持平。通过优化测试系统和实验条件,能够获得更加稳定的探测器性能,更容易在核保障、核物理与辐射探测领域推广。
基金supported by the National Science and Technology Major Project of China(No.J2019-Ⅲ-0009-0053)。
文摘The serpentine convergent-divergent nozzle represents an optimal configuration for nextgeneration fighter aircraft characterized by low detectability and high thrust-to-weight ratio.In contrast to the serpentine convergent nozzle,such configuration offers increased design flexibility with additional parameters,leading to heightened interactions among these parameters.As such,it is crucial to reveal the influence of design parameters on the aerodynamic performance of the serpentine convergent-divergent nozzle and the multifactor interaction,as well as its mechanism.Therefore,the influence,interaction and sensitivity of parameters on the aerodynamic performance of the nozzle were numerically investigated using the orthogonal test method.Additionally,the influence mechanism of the convergence angle,throat aspect ratio,and axial length to inlet diameter on the flow characteristics of the nozzle was investigated in detail.The results show that the convergence angle is identified as the main factor affecting the aerodynamic parameters of the nozzle.As the convergence angle increases,the thrust coefficient,total pressure recovery coefficient and discharge coefficient gradually decrease.The interaction between throat aspect ratio and other parameters is obvious.Different design parameters affect the local loss and the friction loss by affecting the curvature and wetted perimeter area,resulting in different aerodynamic characteristics of serpentine convergent-divergent nozzle.
