Aerodynamic optimization of helicopter rear fuselage

CFD simulation of helicopter rotor flow based on unsteady actuator disk model

Helicopters are frequently operating in confined areas where the complex flow fields that develop in windy conditions may result in dangerous situations. Tools to analyse the interaction between rotorcraft wakes and ground obstacles are therefore essential. This work, carried out within the activity of the GARTEUR Action Group 22 on “Forces on Obstacles in Rotor Wake”, attempts to assess numerical models for this problem. In particular, a helicopter operating in hover above a building as well as in its wake, one main rotor diameter above the ground, has been analysed. Recent tests conducted at Politecnico di Milano provide a basis for comparison with unsteady simulations performed, with and without wind. The helicopter rotor has been modelled using steady and unsteady actuator disk methods, as well as with fully resolved blade simulations. The results identify the most efficient aerodynamic model that captures the wakes interaction, so that real-time coupled simulations can be made possible. Previous studies have already proved that the wake superposition technique cannot guarantee accurate results if the helicopter is close to the obstacle. The validity of that conclusion has been further investigated in this work to determine the minimum distance between helicopter and building at which minimal wake interference occurs.

https://link.springer.com/content/pdf/10.1007%2Fs13272-017-0259-y.pdf

Numerical modelling of the aerodynamic interference between helicopter and ground obstacles

Numerical investigations on drag reduction of a civil light helicopter fuselage

The aim of this paper is to present aerodynamic analyses of realistic fuselage configurations using computational fluid dynamics. A development model of the Ansat helicopter is employed. The model is tested at the subsonic wind tunnel of the Kazan National Research Technical University/Kazan Aviation Institute for a range of Reynolds numbers, pitch, and yaw angles. The computational fluid dynamics results were found to be in fair agreement with the test data and revealed flow separation at the rear of the fuselage. Once confidence in the computational fluid dynamics method was established, further modifications were introduced to the fuselage model to demonstrate drag reduction via small shape changes. The contribution to the overall drag from each fuselage part and the interference drag between the main fuselage components were also investigated.

Computational Fluid Dynamics Modeling of Helicopter Fuselage Drag

This paper investigates the aerodynamic lift and drag of the ANSAT helicopter fuselage prototypes using Computational Fluid Dynamics. The CAD model of the fuselage was meshed using an unstructured grid and computed using a viscous flow model under the assumption of steady flow conditions. To account for the influence of the helicopter rotor an actuator disk model was used and the results were compared with computations for the isolated fuselage. The contributions to the total drag of the individual helicopter fuselage components were also studied using different turbulence models. The key components of the fuselage drag were identified.

CFD Simulation of Fuselage Aerodynamics of the "ANSAT" Helicopter Protype

Low fuselage drag has always been a key target of helicopter manufacturers. Therefore, this paper focuses on CFD predictions of the drag of several components of a typical helicopter fuselage. In the first section of the paper, validation of the obtained CFD predictions is carried out using wind tunnel measurements. The measurements were carried out at the Kazan National Research Technical University n.a. A. Tupolev. The second section of the paper is devoted to the analysis of drag contributions of several components of the ANSAT helicopter prototype fuselage using the RANS approach. For this purpose, several configurations of fuselages are considered with different levels of complexity including exhausts and skids. Depending on the complexity of the considered configuration and CFD mesh both the multi-block structured HMB solver and the unstructured commercial tool Fluent are used. Finally, the effect of an actuator disk on the predicted drag is addressed.

A.O. Garipov

Papers

CFD Simulation of Fuselage Aerodynamics of the "ANSAT" Helicopter Protype

Simulation of Flow around Isolated Helicopter Fuselage