雨水口可以将地表径流输送至排水管网,减少地面径流量,在城市洪涝治理中起关键作用。为了充分掌握雨水口泄流特性,基于FLUENT6.3流体力学软件,对雨水口泄流进行三维数值模拟。采用VOF(Volume of fluid)方法来捕捉自由液面,利用RNGk-ε...雨水口可以将地表径流输送至排水管网,减少地面径流量,在城市洪涝治理中起关键作用。为了充分掌握雨水口泄流特性,基于FLUENT6.3流体力学软件,对雨水口泄流进行三维数值模拟。采用VOF(Volume of fluid)方法来捕捉自由液面,利用RNGk-ε紊流模型使气液两相流时均方程组封闭,利用非定常流动PISO(Pressure implicit with splitting of operators)算法求解速度与压力的耦合方程组。分别对51组不同水深、不同流速下的雨水口泄流特性进行模拟。模拟结果表明:雨水口的泄流特性在雨篦子淹没前后表现出不同的变化规律。当雨水口未被淹没时,雨水以自由堰流形式下泄;当雨水口已经被淹没时,雨水以淹没堰流形式下泄。基于数值模拟数据以及量纲分析法,建立了雨水口下泄流量系数与篦前水流的佛汝德数之间的经验关系。研究成果有助于深化对雨水口泄流过程的认识,为城市防洪减灾提供定量依据。展开更多
The steady and unsteady leakage flow and heat transfer characteristics of the rotor blade squealer tip were conducted by solving Reynolds-Averaged Navier-Stokes （RANS） equations with k-co turbulence model. The first...The steady and unsteady leakage flow and heat transfer characteristics of the rotor blade squealer tip were conducted by solving Reynolds-Averaged Navier-Stokes （RANS） equations with k-co turbulence model. The first stage of GE-E3 engine with squealer tip in the rotor was adopted to perform this work. The tip clearance was set to be 1% of the rotor blade height and the groove depth was specified as 2% of the span. The results showed that there were two vortexes in the tip gap which determined the local heat transfer characteristics. In the steady flow field, the high heat transfer coefficient existed at several positions. In the unsteady case, the flow field in the squealer tip was mainly influenced by the upstream wake and the interaction of the blades potential fields. These unsteady effects induced the periodic variation of the leakage flow and the vortexes, which resulted in the fluctuation of the heat transfer coefficient. The largest fluctuation of the heat transfer coefficient on the surface of the groove bottom exceeded 16% of the averaged value on the surface of the squealer tip.展开更多
文摘雨水口可以将地表径流输送至排水管网,减少地面径流量,在城市洪涝治理中起关键作用。为了充分掌握雨水口泄流特性,基于FLUENT6.3流体力学软件,对雨水口泄流进行三维数值模拟。采用VOF(Volume of fluid)方法来捕捉自由液面,利用RNGk-ε紊流模型使气液两相流时均方程组封闭,利用非定常流动PISO(Pressure implicit with splitting of operators)算法求解速度与压力的耦合方程组。分别对51组不同水深、不同流速下的雨水口泄流特性进行模拟。模拟结果表明:雨水口的泄流特性在雨篦子淹没前后表现出不同的变化规律。当雨水口未被淹没时,雨水以自由堰流形式下泄;当雨水口已经被淹没时,雨水以淹没堰流形式下泄。基于数值模拟数据以及量纲分析法,建立了雨水口下泄流量系数与篦前水流的佛汝德数之间的经验关系。研究成果有助于深化对雨水口泄流过程的认识,为城市防洪减灾提供定量依据。
基金supported by China National Basic Research Program (973 Program),Project No.2007 CB 210107
文摘The steady and unsteady leakage flow and heat transfer characteristics of the rotor blade squealer tip were conducted by solving Reynolds-Averaged Navier-Stokes （RANS） equations with k-co turbulence model. The first stage of GE-E3 engine with squealer tip in the rotor was adopted to perform this work. The tip clearance was set to be 1% of the rotor blade height and the groove depth was specified as 2% of the span. The results showed that there were two vortexes in the tip gap which determined the local heat transfer characteristics. In the steady flow field, the high heat transfer coefficient existed at several positions. In the unsteady case, the flow field in the squealer tip was mainly influenced by the upstream wake and the interaction of the blades potential fields. These unsteady effects induced the periodic variation of the leakage flow and the vortexes, which resulted in the fluctuation of the heat transfer coefficient. The largest fluctuation of the heat transfer coefficient on the surface of the groove bottom exceeded 16% of the averaged value on the surface of the squealer tip.
