Secondary flow in a turbine blade cascade

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CFD analysis of turbulent cross-flow in a staggered tube bundle equipped with grooved cylinders

This study describes the Computational Fluid Dynamics (CFD) analysis of the turbulent cross-flow in a staggered tube bundle with transverse and longitudinal pitch-to-diameter ratio of 3.8 and 2.1 respectively. Two Longitudinal grooves are placed on the external surface at 90° and 270° degrees. Each cylinder has two grooves on the external surface of the cylinder. The Navier-Stokes equations of the turbulent flow are solved using Spalart almaras, k-ε realizable and k-ω SST, turbulence models provided by Fluent CFD code. The staggered tube bundle geometry simulations were performed at steady conditions. An adapted grid using static pressure, pressure coefficient and velocity gradient, furthermore, a second order upwind scheme were used. The CFD results were in agreement with the experimental data. The study demonstrates the capability of the CFD calculations in predicting flow characteristics around the bundl

Experimental investigation of turbulent flow past four grooved and smooth cylinders in an in-line square arrangement

An experimental study of turbulent flow past four cylinders in square arrangement with a space ratio of (T/D = P/D = 2.88) is performed. The investigation focuses on effects of Reynolds number and the shape of cylinders on the force and pressure coefficients of the cylinders. Two cases are investigated: four smooth cylinders (case1) and four grooved cylinders (case2). The cylinders are equipped with two grooves placed on the external surface at 90° and 270° degrees. The pressure distributions along the tubes (22 circumferential pressure taping) were determined for a variation of the azimuthal angle from 0 to 360deg. The drag and lift forces are measured using the TE 44 balance. The results show a bistable flow often exists behind the downstream cylinders is observed. By rising the Reynolds number the pressure coefficient increases in the absolute value