Numerical Simulation Of Vortex Shedding On Gas-liquid Two-phase Flow Around Circular Cylinders

Gas-liquid two-phase cross flow over cylinders is very familiar in industry fields. Under some conditions, vortexes are alternately shed from each side of the cylinder, which induces the fluctuating forces acting on the cylinder. It decreases the operating time of the equipment. For the purpose of the long-term reliability and the safety designing of the industrial equipment, gas-liquid two-phase vortex street is simulated.To vertical upward pipe, the characteristic of the vortex shedding based on gas- liquid two-phase flow around staggered column bundle is simulated in the text. The governing equations of gas-liquid two-phase flow are obtained based on the volume-average method. The two-phase flow's equations of the drag, lift and the inter-phase force of added mass force are deduced. The RNG k ?εturbulence model was used in the gas-liquid two-phase flow with the enhanced wall function for the near wall treatment. With the help of numerical calculation on gas-liquid two-phase flow around staggered column bundle, we find that the characteristics of the vortex shedding are affected by pitch ratio, void fraction and Reynolds number. With the pitch ratio increased, Strouhal number, lift coefficient, power spectrum's peak value, vortex street frequency and drag coefficient increased too. And the characteristic number of different row is different. With void fraction and Reynolds number increased, lift coefficient decreased; when the void fraction is up to one point and increasing, lift coefficient increased; with Reynolds number increased, lift coefficient increased too. With Reynolds number increased, vortex street frequency increased, power spectrum's peak value decreased; with void fraction increased peak value decreased too; drag coefficient decreased little with void fraction increased.To validate the accuracy of the numerical result, the result of simulation is compared with the experiment's, which is gained by using PIV to shoot pictures of flow field based on gas-liquid two-phase flow around staggered column bundle, and calculating the vortex shedding period through the comparison of pictures. The simulation and experimental results agree well with each other, so the accuracy of the numerical result is validated.