Martinez-Valle, Wilmer A.
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Publication Effects of external conditions on the boundary layers of adjacent blades on a compressor cascade(2018-12-12) Martinez-Valle, Wilmer A.; Torres-Nieves, Sheilla; College of Engineering; Cancelos Mancini, Silvina; Araya, Guillermo; Department of Mechanical Engineering; Rivera Gallego, WilsonIn commercial aircraft engines, improvements of 1% in overall engine efficiency represent millions of dollars in fuel savings and a considerable reduction of CO emissions. Analyzing, understanding and optimizing each process within the gas turbine is highly important. For the scope of this study, the airfoils in an axial-compressor, one of the primary components of the engine, will be studied. The general purpose of the axial-compressor in a gas turbine is to convert rotational mechanical energy into increased pressure of the flow. However, when operating beyond the design point, the external conditions of the flow around the compressor blade become unstable and the flow loss increases. The turbulent flow at such high pressures has yet to be fully understood in the literature. It is known that boundary layer development has a direct impact on the flow losses, hence, on the aerodynamic performance. The study of the region closer to the surface of the blade is of particular interest since the flow interacts with the blade surface and the free-stream. The turbulent boundary layer experiments were performed to study the influence of the Free Stream Turbulence (FST) and the external pressure gradient on a smooth surface of the NACA 65-410 airfoil profile. The pressure distribution over NACA 65-410 compressor airfoils was measured using pressure taps and connected to a digital manometer bank. The experimental data obtained from this research was compared with numerical approximation and experimental data from other authors, allowing the validation of the present research. Overall, all of the external conditions that were analyzed, such as FST and PG, have an impact on the behavior of the boundary layer development. For the case of the aerodynamic performance, experiments with and without FST were performed. When all the cases were compared, for both the individual case and the cascade case, it was observed that the FST does in fact influence the experiments. The FST provokes the reduction of the coefficient of pressure (Cp), the lift coefficient (Cl) and the drag coefficient (Cd). Therefore, when talking about modeling and designing compressor axial blades, the FST and PG must be considered. Identifying and reducing the external conditions effects in an experiment will certainly aid in reducing the inaccuracies that perhaps come from modeling.