Drag Coefficient and Two Phase Friction Multiplier on Tube Bundles Subjected to Two Phase Cross Flow

Abstract

An approximate analytical model, to predict the drag coefficient on a cylinder and the twophase Euler number for upward twophase crossflow through horizontal bundles, has been developed. To verify the model, two sets of experiments were performed with an air–water mixture for a range of pitch mass fluxes and void fractions. The experiments were undertaken using a rotated triangular (RT) array of cylinders having a pitchtodiameter ratio of 1.5 and cylinder diameter 38 mm. The void fraction model proposed by Feenstra et al. was used to estimate the void fraction of the flow within the tube bundle. An important variable for drag coefficient estimation is the twophase friction multiplier. A new drag coefficient model has been developed, based on the singlephase flow Euler number formulation proposed by Zukauskas et al. and the twophase friction multiplier in duct flow formulated by various researchers. The present model is developed considering the Euler number formulation by Zukauskas et al. as well as existing twophase friction multiplier models. It is found that Marchaterre's model for twophase friction multiplier is applicable to air–water mixtures. The analytical results agree reasonably well with experimental drag coefficients and Euler numbers in air–water mixtures for a sufficiently wide range of pitch mass fluxes and qualities. This model will allow researchers to provide analytical estimates of the drag coefficient, which is related to twophase damping.