Gas turbine engines, such as those used in aerospace applications, often have a combination of a rotor assembly and stator assembly positioned in the forward section of the engine. It is known that the movement of air, propelled by the rotor assembly across the stator assembly, may generate undesirable noise. It is generally desired to design engine components so as to minimize this potential noise generation.
Within the limited space constraints in the rotor-stator-strut system of a turbine engine, the discrete tone noise generated by rotor-stator and rotor-strut interactions should preferably be minimized by the three-dimensional shaping of the blades, while maintaining aerodynamic and mechanical performance of the system. The possible three-dimensional shapes of the rotor blades, stator vanes, and struts may be constrained by a variety of design objectives and practical considerations. In regards to the stator vane, these constraints may include the limited overall length of the rotor-stator-strut system, aerodynamic performance requirements at a variety of operating conditions, mechanical robustness, and manufacturing and assembly constraints.
Prior techniques of addressing the above-noted constraints include combinations of straight sweeping of the stator vane by linear displacement of the airfoil section so that the tip of the stator vane is displaced aft, and straight leaning of the stator vane in the direction of rotor rotation by linear displacement of the airfoil section. Straight leaning of the stator vane in the direction of rotor rotation can provide reductions in tone noise but is usually associated with aerodynamic losses in the hub region, where it is aerodynamically preferable to lean the stator vane in the direction opposite to rotor rotation. Thus it would be desired to develop further improved stator vane designs that achieve a noise reduction but without suffering from unacceptable aerodynamic losses.
Hence there is an ongoing need to provide improved stator vanes that have low noise characteristics. It would be desired to provide a stator vane design that fits within the structural limitations of the rotor-stator system of a gas turbine engine. It would further be desired that the stator vane provide good aerodynamic performance while maintaining good acoustic characteristics. The present invention addresses one or more of these needs.