CALCULATION METHOD OF LOADING OF COMPLEX AERODYNAMIC PROFILE NOZZLE BASED ON IMPROVED NLI FACTOR

The nozzle is a very important component of the aircraft propulsion system. In recent years, with the rapid development of stealth aircraft technology, complex aerodynamic profile nozzles have been increasingly widely applied. The structural safety and life assessment of complex aerodynamic profile nozzles has become a hot research direction, while the loads on complex contour nozzles are one of the fundamental data for such assessments. To further enhance the precision and efficiency of methods for rapidly generating large-scale flight load data for complex nozzle geometries, this study builds upon the Nozzle Load Influence (NLI) factor calculation theory. By employing a three-point NLI factor interpolation technique, an Improved Nozzle Load Influence (INLI) factor is developed to calculate nozzle loads under various flight conditions, including different altitudes, Mach numbers, and engine operating states. A comparative analysis of three nozzle load calculation methods—CFD, NLI, and INLI—is conducted to evaluate their applicability, computational accuracy, and efficiency for calculating loads under different internal flow states of the nozzle. The results demonstrate that compared to the NLI method, the INLI-based nozzle load calculation method demonstrates significant improvements in applicability, computational accuracy, and efficiency. Specifically, it exhibits no restrictions on target calculation states, controllable accuracy for wall loads at any nozzle location, a reduction of maximum relative error from 5% to 2%, and a 65% increase in computational efficiency.