Noise suppressing turbofan nozzles and method

In a turbofan including a primary exhaust nozzle, core means for producing a primary exhaust flow through the primary exhaust nozzle, a fan nozzle encircling the primary exhaust nozzle and fan means for producing a fan flow through the fan nozzle, the velocity of the primary exhaust flow produced by the core means being greater than the velocity of the fan flow produced by the fan means, the improvement comprising the fan nozzle and the primary exhaust nozzle being constructed and arranged relatively so that at the discharge end of the rearmost nozzle the upright thickness of the fan flow below the primary exhaust flow is greater than the lateral thickness of the fan flow at a location laterally of the primary exhaust flow for suppressing jet noise perceived below the turbofan, the discharge end of the primary exhaust nozzle being canted to offset the primary exhaust flow upward to effect the greater thickness of fan flow below the primary exhaust flow.

In a turbofan including means for producing a high velocity discharge gas flow and means for producing a separate lesser velocity discharge gas flow, said two flow-producing means including separate gas discharge nozzles having respective portions of generally circular cross-section which portions are generally concentric at a location forward of the discharge ends of such nozzles, the improvement comprising the two flow-producing means including means for disposing at least the major portion of the lesser velocity gas flow discharged from the turbofan below at least the major portion of the high velocity gas flow discharged from the turbofan for suppressing jet noise perceived below the turbofan.

In a turbofan including a primary exhaust nozzle, core means for producing a primary exhaust flow through the primary exhaust nozzle, a fan nozzle encircling the primary exhaust nozzle and fan means for producing a fan flow through the fan nozzle, the velocity of the primary exhaust flow produced by the core means being greater than the velocity of the fan flow produced by the fan means, the improvement comprising the fan nozzle and the primary exhaust nozzle being constructed and arranged relatively so that at the discharge end of the rearmost nozzle the upright thickness of the fan flow below the primary exhaust flow is greater than the lateral thickness of the fan flow at a location laterally of the primary exhaust flow for suppressing jet noise perceived below the turbofan, the primary exhaust nozzle being a multitube mixing nozzle and the tubes of said multitube mixing nozzle being inclined upward toward their discharge ends to effect the greater thickness of fan flow below the primary exhaust flow.

In a turbofan including a primary exhaust nozzle, core means for producing a primary exhaust flow through the primary exhaust nozzle, a fan nozzle encircling the primary exhaust nozzle and fan means for producing a fan flow through the fan nozzle, the velocity of the primary exhaust flow produced by the core means being greater than the velocity of the fan flow produced by the fan means, the improvement comprising the discharge end portion of the primary exhaust nozzle being deflected upward relative to the discharge end portion of the fan nozzle so that more of the fan flow is discharged below the primary exhaust flow than above the primary exhaust flow for suppressing jet noise perceived below the turbofan.

In a turbofan including a primary exhaust nozzle, core means for producing a primary exhaust flow through the primary exhaust nozzle, a fan nozzle encircling the primary exhaust nozzle and fan means for producing a fan flow through the fan nozzle, the velocity of the primary exhaust flow produced by the core means being greater than the velocity of the fan flow produced by the fan means, the improvement comprising the fan nozzle and the primary exhaust nozzle being constructed and arranged relatively so that at the discharge end of the rearmost nozzle the upright thickness of the fan flow below the primary exhaust flow is greater than the lateral thickness of the fan flow at a location laterally of the primary exhaust flow for suppressing jet noise perceived below the turbofan, the discharge end of the primary exhaust nozzle being flattened such that its horizontal dimension is greater than its vertical dimension to effect the greater thickness of fan flow below the primary exhaust flow.