Performance estimation for serpentine nozzle coupled with aero-engine

In order lo increase the survivability of the fighter aircraft, serpentine nozzles are applied in series of stealth bombers and Unmanned Aerial Vehicles (UAVs) for their predominant performance in suppressing infrered radiation signature (IRS) emitted by engine exhausts. The aim of this paper is to qualitatively study the influences of the serpentine nozzle on the performance of aero-engine. It is commonly known that excessive geometric parameters are included in the double serpentine nozzle design and, as a result, the performance estimation model for serpentine nozzle coupled with aero-engine is established by combining design of experiment (DOE), response surface methodology (RSM) and aero-engine simulation program based on component characters. In coupling model, seven aerodynamic and geometric parameters were involved in the model, e.g. the length-daimeter ratio; the axial length ratio; the offset distance, the exit area and the exit width of the first serpentine paragraph: the exit aspect ratio of the second serpentine paragraph: and nozzle pressure ratio (.YPR), are taken into consideration. Results show that the interaction effects between different parameters are evident for both the thrust coefficient and the flux coefficient; the thrust of the aero-engine coupling with the serpentine nozzle reduces 0.85%-1.81%, and the specific fuel consumption (SFC) increases 1.43%-1.92% as compared to the aero-engine coupling with the axisvmmetric nozzle.