期刊文献+
共找到10篇文章
< 1 >
每页显示 20 50 100
新型自激式波动射流发生装置及其射流冲击特性
1
作者 艾白布·阿不力米提 庞德新 +4 位作者 刘永红 孙长友 杨博源 王一全 李辉 《石油机械》 北大核心 2022年第10期66-72,共7页
为了对新型自激式波动射流发生装置及其射流冲击特性进行研究,利用Fluent软件对装置工作原理、流动及冲击特性进行数值模拟,并加工制作装置样机;通过全尺寸波动射流冲击特性试验对模拟结果进行验证,揭示了装置自激波动射流机理,得到主... 为了对新型自激式波动射流发生装置及其射流冲击特性进行研究,利用Fluent软件对装置工作原理、流动及冲击特性进行数值模拟,并加工制作装置样机;通过全尺寸波动射流冲击特性试验对模拟结果进行验证,揭示了装置自激波动射流机理,得到主射流雷诺数、围压对装置性能的影响规律。研究结果表明:装置出口因附壁效应形成规律的波动射流,装置上部喷嘴与下部喷嘴的压力、流速波动基本一致;出口流速幅值受主射流雷诺数影响较大,且成正比关系;雷诺数对频率影响不大;自激式波动射流发生装置的冲击特性受围压影响较小;随着排量的提高,出口流速整体呈上升趋势,极值、幅值均与排量呈正相关;试验结果与数值模拟结果趋势相符,数值误差为8.7%,进一步验证了数值模拟方法用于瞬态射流过程预测的可行性。研究结果可为新型自激式波动射流发生装置的进一步优化提供依据。 展开更多
关键词 自激波动射流发生装置 波动射流 附壁效应 自激振荡 冲击特性
下载PDF
The internal COF features in Dome A of Antarctica revealed by multi-polarization-plane RES 被引量:5
2
作者 王帮兵 田钢 +1 位作者 崔祥斌 张向培 《Applied Geophysics》 SCIE CSCD 2008年第3期230-237,共8页
The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition (MPT) and the relationship between greenhouse gas and climate change. The region near ... The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition (MPT) and the relationship between greenhouse gas and climate change. The region near Dome A in Antarctica satisfies the conditions for obtaining million-years-old ice since it has low temperatures and low accumulation rates. We analyze the corresponding relation between radar wave features and the crystal orientation fabric (COF) types based on the results of multi-polarization plane radio echo sounding (RES). The results show that, even in the summit of the ice sheet, the COF type is not perfect, but is an elongated single-pole COF. Principal-axis-orientation differences of the COF among the different periods exist and reveal that the ice flow orientations are not constant but deviate clockwise with the increasing depth. This may be related to the adjacent basal valley or both height and position changes of the summit during the glacial-interglacial periods. 展开更多
关键词 Crystal orientation fabric (COF) radio echo sounding (RES) multi-polarization plane technique ice flow orientation
下载PDF
Research on Mechanism of Airshooting 被引量:2
3
作者 邵鹏 程玉生 《Journal of China University of Mining and Technology》 2001年第1期51-55,共5页
The composition and ultimate principle of airshooting experimental system were expounded, and the mechanism of airshooting was emphatically discussed on the basis of experiments. The results indicate that the fracture... The composition and ultimate principle of airshooting experimental system were expounded, and the mechanism of airshooting was emphatically discussed on the basis of experiments. The results indicate that the fracture of medium under airshooting resultes from both shock action of air spray and quasi static dilatation of high pressure air. The action of air spray leads to the initial fracture of the wall of borehole and arouses stress wave to propagate in the medium. The quasi static dilatation of high pressure air results in the propagation of initial fractures and produces shear fracture in the medium along the free boundary. Along the direction of minimum burden, the superposition of quasi static and dynamic stress fields can prompt the propagation of cracks. The superposition of the reflected wave, which comes from multiple free surfaces, will result in the fracture of medium also if multiple free boundaries exist. 展开更多
关键词 mechanism of airshooting stress wave air spray high pressure air
下载PDF
Profile and Character of Atmospheric Structure Constant of Refractive Index C_n^2
4
作者 SUN Gang WENG Ning-Quan +1 位作者 XIAO Li-Ming WU Yi 《Atmospheric and Oceanic Science Letters》 2012年第3期270-272,共3页
Random fluctuations of turbulence bring random fluctuations of the refractive index, making the atmosphere a random fluctuation medium that destroys the coherence of light-waves. Research in atmospheric turbulence is ... Random fluctuations of turbulence bring random fluctuations of the refractive index, making the atmosphere a random fluctuation medium that destroys the coherence of light-waves. Research in atmospheric turbulence is actually the investigation of the atmospheric refractive index. The atmospheric structure constant of refractive index, C n 2 , is an important parameter denoting atmospheric turbulence. In this paper, C n 2 is measured during the day and at night and in all four seasons using a high sensitivity micro-thermal meter QHTP-2. The vertical profile of C n 2 in Hefei (0-30 km) is investigated by the analysis of experimental data. The average profile of C n 2 in Hefei exhibits conspicuous day and night differences with increased altitude. The distribution of log(C n 2 ) is nearly normal and has conspicuous seasonal differences. 展开更多
关键词 applied optics atmospheric turbulence atmospheric structure constant of refractive index variance profile
下载PDF
Flow Characteristics of Rectangular Underexpanded Impinging Jets 被引量:1
5
作者 Minoru YAGA Yoshio KINJO +1 位作者 Masumi TAMASHIRO Kenyu OYAKAWA 《Journal of Thermal Science》 SCIE EI CAS CSCD 2006年第1期59-64,30,共7页
In this paper, the flow fields of underexpanded impinging jet issued from rectangular nozzles of aspect ratio 1, 3 and 5 are numerically and experimentally studied. Two dimensional temperature and pressure distributio... In this paper, the flow fields of underexpanded impinging jet issued from rectangular nozzles of aspect ratio 1, 3 and 5 are numerically and experimentally studied. Two dimensional temperature and pressure distributions are measured by using infrared camera and the combination of a pressure scanning device and a stepping motor, respectively. The variation of the stagnation pressure on the impinging plate reveals that a hysteretic phenomenon exists during the increasing and decreasing of the pressure ratio for the aspect ratio of 3.0 and 5.0. It is also found that the nozzle of aspect ratio 1.0 caused the largest total pressure loss Pc /p0= 0.27 at the pressure ratio of Po /p0 = 6.5, where Pc is the stagnation center pressure on the wall, P0 the upstream stagnation pressure, Pb the ambient pressure. The other two nozzles showed that the pressure loss Pc / P0 =0.52 and 0.55 were achieved by the nozzles of the aspect ratio 3,0 and 5.0, respectively. The comparison between the calculations and experiments is fairly good, showing the three dimensional streamlines and structures of the shock waves in the jets. However, the hysteresis of the pressure variations observed in the experiments between the pressure ratio of 3.5 and 4.5 cannot be confirmed in the calculations. 展开更多
关键词 compressible flow shock wave under-expanded rectangular impinging jet CFD.
原文传递
Phase Invariant Proper Orthogonal Decomposition for the Study of a Compressed Vortex
6
作者 Julien MOREAU Mark FOGLEMAN +1 位作者 G.CHARNAY J.BOREE 《Journal of Thermal Science》 SCIE EI CAS CSCD 2005年第2期108-113,共6页
We propose here an experimental investigation of a vortex submitted to a radial perturbation while being compressed. This experiment reproduces a model situation of the complex flows that take place in a real engine c... We propose here an experimental investigation of a vortex submitted to a radial perturbation while being compressed. This experiment reproduces a model situation of the complex flows that take place in a real engine cylinder. An isolated tumbling flow is first submitted to an injection of fluid and then compressed and measurements are realised by Particle Image Velocimetry (PIV). The Proper Orthogonal Decomposition is known to be an unbiased method to identify the coherent structures of turbulent flows. It is possible to make this decomposition for a given phase or to create a set of basis functions with the whole set of compression stroke velocity fields.First, the experimental set-up will be presented, then the second part provides the POD principle. Results of phased POD decomposition of the compression of the unperturbated vortex will be presented. Finally results from the time invariant POD will be discussed to study the influence of the jet perturbation in the compression of a vortex. 展开更多
关键词 TURBULENCE POD PIV cycle to cycle fluctuations.
原文传递
Effect of Exit Geometry of Tail Pipe on the Performance of Pulse Jet Engines
7
作者 Toshihiro NAKANO ShigeruMATSUO +1 位作者 KenbuTERAMOTO ToshiakiSETOGUCHI 《Journal of Thermal Science》 SCIE EI CAS CSCD 2006年第3期263-268,共6页
In this paper,the effect of geometries of tube open end on the shock,compression and expansion wavespropagating in the tube was investigated numerically and experimentally.One of them is a conventional straightshock t... In this paper,the effect of geometries of tube open end on the shock,compression and expansion wavespropagating in the tube was investigated numerically and experimentally.One of them is a conventional straightshock tube with an open end.The other has a divergent tail tube at the exit.Applying a divergent tail tube(flaretube)to an open end shock tube,the period of one-cycle process could be shortened and the pressure behind theexpansion wave produced at the exit of the shock tube could be lowered much more below the atmosphericpressure than that produced in the straight tube.The results suggested that the intake air into the engine wassignificantly increased by applying a flare tube instead of a straight tube. 展开更多
关键词 compressible flow shock wave expansion wave pulse jet numerical simulation
原文传递
Behavior of Shock Waves Formed by Unsteady Supersonic Jet Injected into Cell
8
作者 Minoru YAGA Hiroshi FUKUOKA +1 位作者 Yasushi IWATA Toshio TAKIYA 《Journal of Thermal Science》 SCIE EI CAS CSCD 2008年第1期50-55,共6页
The unsteady behavior of flow driven by a jet suddenly injected into a cell is numerically studied by solving the axisymmelric two-dimensional compressible Navier-Stokes equations. The system of the calculation is a m... The unsteady behavior of flow driven by a jet suddenly injected into a cell is numerically studied by solving the axisymmelric two-dimensional compressible Navier-Stokes equations. The system of the calculation is a model of the laser ablation of a certain duration followed by a discharging process through the exit hole at the down- stream end of the cell. In the calculations, the contour of the cell is changed while other parameters such as the Mach number of the jet, its duration, and the diameter of the cell exit are fixed. Monitoring the velocity at the exit hole is used to investigate the influence of the shape on the interaction between the shock wave and the jet. As the result, it was found that the velocity peak value and its arrival time at the downstream end of the cell exit are determined by the diameter of the cell. 展开更多
关键词 Shock wave CFD supersonic flow unsteady jet velocity variation
原文传递
Hysteretic Phenomenon of Shock Wave in a Supersonic Nozzle 被引量:1
9
作者 Toshiaki Setoguchi Shigeru Matsuo +2 位作者 M.M. Ashraful Alam Junji Nagao Heuy Dong Kim 《Journal of Thermal Science》 SCIE EI CAS CSCD 2010年第6期526-532,共7页
In recent years, hysteretic phenomena in fluid flow systems drew attention for their great variety of industrial and engineering applications. When the high-pressure gas is exhausted to atmosphere from the nozzle exit... In recent years, hysteretic phenomena in fluid flow systems drew attention for their great variety of industrial and engineering applications. When the high-pressure gas is exhausted to atmosphere from the nozzle exit, the expanded supersonic jet with the Mach disk is formed at a specific condition. In two-dimensional expanded supersonic jet, the hysteresis phenomenon for the reflection type of shock wave is occurred under the quasi-steady flow and the transitional pressure ratio between the regular reflection and Mach reflection is affected by this phe- nomenon. However, so far, there are very few researches for the hysteretic phenomenon of shock wave in a supersonic internal flow and the phenomenon has not been investigated satisfactorily. The present study was concemed with the experimental and numerical investigations of hysteretic phenomena of shock wave in a supersonic nozzle, and discussed the relationship between hysteresis phenomenon and rate of the change of pressure ratio with time. 展开更多
关键词 compressible flow HYSTERESIS internal flow shock wave supersonic nozzle
原文传递
Global Solutions of Shock Reflection by Wedges for the Nonlinear Wave Equation
10
作者 Xuemei DENG Wei XIANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2011年第5期643-668,共26页
When a plane shock hits a wedge head on, it experiences a reflection-diffraction process and then a self-similar reflected shock moves outward as the original shock moves forward in time. In this paper, shock reflecti... When a plane shock hits a wedge head on, it experiences a reflection-diffraction process and then a self-similar reflected shock moves outward as the original shock moves forward in time. In this paper, shock reflection by large-angle wedges for compressible flow modeled by the nonlinear wave equation is studied and a global theory of existence, stability and regularity is established. Moreover, C^0,1 is the optimal regularity for the solutions across the degenerate sonic boundary. 展开更多
关键词 Compressible flow Conservation laws Nonlinear wave system Regularreflection
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部