The 1:1 water model of a twin-roll strip caster was set up based on the Froude number and the Reynolds number similarity criteria. A new type metal delivery system was designed for the twin-roll strip caster. The lev...The 1:1 water model of a twin-roll strip caster was set up based on the Froude number and the Reynolds number similarity criteria. A new type metal delivery system was designed for the twin-roll strip caster. The level fluctuation and the fluid flow in the pool of the water model were measured using the level detector and the 3D-LDV (laser Doppler velocimetry) technology. It is shown that a wedged delivery system can produce the desirable level fluctuation and even fluid flow distribution in the pool Numerical simulations for the water model were performed. Comparisons between the numerical and physical simulation results show good agreement near the side dams.展开更多
The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is studied.The key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase v...The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is studied.The key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase velocities can be characterized.In this study,two experiments are carried out.Firstly,the bubble-chain experiment is performed to investigate the optical response of bubble surface and the corresponding LDV signal.The optical response shows that the light received by the LDV detector is dominated by the reflection component,which is similar to specular reflection to some extent.There are three typical patterns of signals of large bubbles passing through the measurement volume,all of which are with high amplitude and saturated.Then,the upward-flow experiment is conducted to study the statistical characteristics of large bubbles as well as micro tracers and micro bubbles.The results show that the amplitude of signal of millimeter bubbles is about an order of magnitude larger than that of tracers or micro bubbles.Based on this significant difference of the amplitude,we propose a phase discrimination method to distinguish two-phase signals.The capability of the proposed method is tested in a complex bubble flow,and its reliability is verified by bubble tracking velocimetry(BTV)technology.展开更多
Vortex breakdown of the steady axisymmetic rotating flow in a confined cylindrical container with a rotating endwall was numerically and experimentally studied. High-quality precision-controlled turntable facilities w...Vortex breakdown of the steady axisymmetic rotating flow in a confined cylindrical container with a rotating endwall was numerically and experimentally studied. High-quality precision-controlled turntable facilities were established at Shanghai Jiaotong University and Tokyo Denki University independently. Collaborative investigations of vortex breakdown were carried out using CFD, Laser Doppler Velocimetry (LDV) and streakline visualization, respectively. The characteristics of vortex breakdown were delineated in terms of comparative investigation using numerical and experimental results. SIMPLEC scheme and FMG multigrid was applied to numerical simulation. Numerical simulation was extensively compared with streakline visualization and LDV measurements, showing qualitative and quantitative agreements.展开更多
The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Dopp...The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Doppler velocimetry (LDV) technique is successfully applied to measure the periodic flow field in a radial diffuser pump with low-specific speed, in order to investigate the velocity fluctuations caused by the impeller-diffuser interactions both in the impeller and diffuser regions. The velocity fluctuations in the impeller region are quantitatively examined at different radial positions, and the flow structure at the radial gap between two flow components is analyzed at different relative positions. In addition, the downstream effect on the diffuser flow is quantitatively and qualitatively assessed and compared with the turbulence effect.展开更多
基金This work was financially supported by the National Natural Science Foundation of Inner Mongolia of China (No.200408020715).
文摘The 1:1 water model of a twin-roll strip caster was set up based on the Froude number and the Reynolds number similarity criteria. A new type metal delivery system was designed for the twin-roll strip caster. The level fluctuation and the fluid flow in the pool of the water model were measured using the level detector and the 3D-LDV (laser Doppler velocimetry) technology. It is shown that a wedged delivery system can produce the desirable level fluctuation and even fluid flow distribution in the pool Numerical simulations for the water model were performed. Comparisons between the numerical and physical simulation results show good agreement near the side dams.
基金Project supported by the State Key Program of National Natural Science of China(Grant No.91852204)supported by the Program of State Key Laboratory of Marine Equipment(Grant No.SKLMEA-K201910).
文摘The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is studied.The key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase velocities can be characterized.In this study,two experiments are carried out.Firstly,the bubble-chain experiment is performed to investigate the optical response of bubble surface and the corresponding LDV signal.The optical response shows that the light received by the LDV detector is dominated by the reflection component,which is similar to specular reflection to some extent.There are three typical patterns of signals of large bubbles passing through the measurement volume,all of which are with high amplitude and saturated.Then,the upward-flow experiment is conducted to study the statistical characteristics of large bubbles as well as micro tracers and micro bubbles.The results show that the amplitude of signal of millimeter bubbles is about an order of magnitude larger than that of tracers or micro bubbles.Based on this significant difference of the amplitude,we propose a phase discrimination method to distinguish two-phase signals.The capability of the proposed method is tested in a complex bubble flow,and its reliability is verified by bubble tracking velocimetry(BTV)technology.
文摘Vortex breakdown of the steady axisymmetic rotating flow in a confined cylindrical container with a rotating endwall was numerically and experimentally studied. High-quality precision-controlled turntable facilities were established at Shanghai Jiaotong University and Tokyo Denki University independently. Collaborative investigations of vortex breakdown were carried out using CFD, Laser Doppler Velocimetry (LDV) and streakline visualization, respectively. The characteristics of vortex breakdown were delineated in terms of comparative investigation using numerical and experimental results. SIMPLEC scheme and FMG multigrid was applied to numerical simulation. Numerical simulation was extensively compared with streakline visualization and LDV measurements, showing qualitative and quantitative agreements.
基金supported by the National Natural Science Foundation of China(Grant Nos.51339005,51379174 and 51279160)the Doctoral Fund of Ministry of Education of China(Grant No.20126118130002)
文摘The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Doppler velocimetry (LDV) technique is successfully applied to measure the periodic flow field in a radial diffuser pump with low-specific speed, in order to investigate the velocity fluctuations caused by the impeller-diffuser interactions both in the impeller and diffuser regions. The velocity fluctuations in the impeller region are quantitatively examined at different radial positions, and the flow structure at the radial gap between two flow components is analyzed at different relative positions. In addition, the downstream effect on the diffuser flow is quantitatively and qualitatively assessed and compared with the turbulence effect.