Performance evaluation of vaned pipe bends in turbulent flow of liquid propellants

Abstract Computational fluid dynamics techniques were used to analyze turbulent, incompressible flow in a vaned pipe bend that is being considered for use in the liquid propellant feed lines of the space shuttle main engine. The design is an 80° bend that incorporates two turning vanes. Computations were performed using a finite difference code for solving the Navier-Stokes equations in three dimensions using the method of pseudocompressibility, a flux-splitting upwind differencing scheme, and a Baldwin-Barth one-equation turbulence model. To compare and evaluate the performance of the bend under consideration, two other bend designs—an unvaned 80° bend and a simplified 80° vaned bend—were also analyzed. Evaluation of the bend designs was accomplished by comparing the predicted streamwise and cross-stream velocity distributions at the symmetry plane at several streamwise stations and the predicted mean pressure drops. It was observed that the vaned bend under consideration effectively provides uniform streamwise velocity distributions downstream of the bend, reduces cross-stream velocities, and significantly reduces pressure losses.