New patent granted for: Gas Turbine Engine with Low Fan Noise

In accordance with one aspect of the disclosure, a gas turbine engine, method of using and designing such is disclosed. The gas turbine engine may comprise a fan including a plurality of blades, and a variable area fan nozzle. The fan may be configured to have a design point fan tip leading edge relative flow angle .beta..sub.ADP, and may be further configured to have an off-design point fan tip leading edge relative flow angle .beta. at an off-design fan operating point. The variable area fan nozzle may be configured to manipulate the amount of air flowing through the fan so that the absolute value of a difference between the design point fan tip leading edge relative flow angle .beta..sub.ADP and the off-design point fan tip leading edge relative flow angle .beta. is in a specified range.