Aerodynamic simulation method for sling load flight of heavy-lift helicopters oriented toward flight test design

Abstract The safety and cost-effectiveness of helicopter external sling load flight are influenced by numerous factors, including slung load mass as well as sling length and configuration. All the above-mentioned different working conditions will lead to changes in aerodynamic characteristics, further affecting flight safety. Given the larger rotor and fuselage size, heavy-lift helicopters are faced with more complicated aerodynamic interference. Hence, it is imperative to implement the simulation analysis prior to the flight test. The existing aerodynamic simulation methods and models, however, typically fail to balance computational accuracy and efficiency. To address this challenge, this research proposes a computation method for the aerodynamic interference flow field of heavy-lift helicopter external sling load operations that balances computational efficiency and accuracy. More exactly, first and foremost, this research simplifies the modeling process by utilizing a momentum source and unstructured nested grid generation. On such a basis, combined with the k-ω SST turbulence model, the RANS method is employed to improve the computational accuracy of aerodynamic interference. Lastly, while verifying the accuracy of the computation method with a typical heavy-lift helicopter, CH-53E, this research systematically analyzes the aerodynamic interference characteristics of the external sling load of heavy-lift helicopters combined with the computational results.