Prof. Dr. J.C. Páscoa works at the Engineering Faculty of University of Beira Interior (Portugal). He is the head of the 1rst Cycle in Electromechanical Engineering and also works as a researcher in the CAST-Center for Aerospace Sciences and Technology. Professor J. C. Páscoa is also Liaison Officer at the Nuclear Energy Agency of OCDE. He serves as editor for Central European Journal of Engineering.
Abstract: Numerical computation of the flowfield inside a pump is herein used as a numerical laboratory, subject to the
limitations of modeling assumptions and to experimental verification. A numerical computation of the flow inside
a real industrial centrifugal pump is performed that includes a very sophisticated geometry. Conversely to other
computations, in this test case no simplification of the geometry was introduced. Numerical computations are obtained
using Spalart-Allmaras turbulence model. A detailed analysis of the turbulent flowstructure is performed
for the design point and two off design conditions. Additional computations were performed in order to compare
the numerical and experimental pump characteristics; these were obtained under normalized testing conditions.
Further computations are presented for the pump working in reverse turbine mode (PAT). Detailed analyses of the
flow allow a comparison of the internal flow losses when the pump is operating in direct and reverse mode. This
is also useful to help in the selection of an adequate pump geometry that can work in both modes with best efficiency.
Abstract: 3D computations for a highly loaded transonic blade and for a gas turbine stage. Comparison between experimental results and numerical
computations reveals the precision limits of current modeling assumptions. Computations are performed using a time-marching
approach coupled with a mixing-plane model for the exchange of flowfields between stator and rotor domains. Eddy viscosity turbulence
models are applied to compute the flow with and without wall functions. Limitations in performance assessment are presented regarding
the level of detail used for the geometry definition, the mixing-plane approach, and the near wall turbulence model employed.
Abstract: An improved formulation for an iterative inverse design method is presented. The method
solves the time dependent Euler equations in a numerical domain where the blade sections
are iteratively modified, until a prescribed blade load distribution is reached. The mean
tangential velocity and thickness distributions are imposed as design variables. Each design
iteration starts with a blade section modification that is impressed on the camber line.
After generating a new mesh, the flow-field is updated by performing one finite volume
time iteration. The blade modifications and the time-marching computation converge
simultaneously to the required geometry and to the steady state flow solution. The present
time-lagged formulation introduces a new blade thickness distribution term that improves
the convergence rate. An empirical study on the existence and uniqueness problem is presented
for the iterative inverse design method. Results for different blade cascade geometries
showed the improvement of the convergence rate and the robustness of the method,
for the imposed set of design conditions.
