variavel0=<b>Denis Rinaldi Petrucci</b> - denisrpetrucci@uol.com.br Escola Federal de Engenharia de Itajubá
<b>Nelson Manzanares Filho</b> - nelson@iem.efei.br Escola Federal de Engenahria de Itajubá
<b>Abstract.</b> A method for inverse airfoil design of turbomachinery cascades is presented in this paper. The method is based on an iterative correction algorithm with an efficient panel technique for potential flow calculations. Linear vortex distributions on the panels and a consistent procedure for imposing the Kutta condition are applied in order to eliminate the spurious aerodynamic loading that usually appears in the vicinity a cusped trailing edge. A semi-analytical scheme is applied for calculating the influence matrix elements of cascade airfoils. The scheme is purely analytical for isolated bodies. The algorithm searches the airfoil ordinates attending to a given surface velocity distribution with fixed abscissas. It begins with a guessed starting shape and successively modifies it by an iterative process, such that the normal velocity vanishes and the calculated velocity distribution gradually approaches the required one. Each iteration is performed by two main steps: 1) the flow calculation step; 2) the geometrical marching step, where the calculated velocity distribution is compared with the required one and a consistent criterion is applied to modify the current shape and to obtain another one more close to the target shape. The geometrical marching is conducted by varying the panel slopes as a function of the normal velocity excess induced by the difference between the required and calculated velocities. A scheme is applied in order to close the body shape. For calculating the normal velocity excess one verifies that fixing the influence matrix of the starting shape contributes for accelerating the convergence process. A useful aspect of the proposed method is its ability in producing the correct incidence angle of the desired airfoils. Various benchmark tests are presented for standard cascades (Gostelow) as well isolated airfoils (Joukowski).
<b>Keywords.</b> Inverse method, Turbomachinery, Airfoils, Cascades, Panel Method.