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Generation of Advanced Helicopter Experimental Aerodynamic Database for CFD Code Validation


During the last ten years, considerable progress has been made in developing aerodynamic prediction capabilities for isolated helicopter components. This progress has been made possible due to the co-operations that were partly funded by European research projects. Today, cutting-edge CFD codes are available that are capable of predicting the viscous flow around main rotor-fuselage configurations. The greatest shortcoming for qualifying these methods as design tools in the industrial design process is the lack of detailed experimental validation data for complete helicopters.

Project objectives

The main objectives of GOAHEAD are:

  • To enhance the aerodynamic prediction capabilities of Europe’s helicopter industry with regard to complete helicopter configurations.
  • To create an experimental database for validation of 3D unsteady Reynolds-averaged Navier-Stokes (URANS) CFD methods for unsteady viscous flows, including rotor dynamics for complete helicopter configurations (main rotor-fuselage-tail rotor), with emphasis on viscous phenomena like flow separation and transition from laminar to turbulent flow.
  • To evaluate and validate Europe’s most elaborate URANS solvers for the prediction of viscous flow around a complete helicopter, including fluid-structure coupling.
  • To establish best practice guidelines for the numerical simulation of the viscous flow around helicopter configurations.
GOAHEAD aims to validate URANS CFD codes for complete modern transport helicopter configurations.
GOAHEAD aims to validate URANS CFD codes for complete modern transport helicopter configurations.

Description of the work

The project will have a four-year duration and will consist of five Work Packages. In Work Package 1 the detailed specifications of the test matrix for the wind tunnel experiment and the CFD evaluation and validation task will be elaborated. Work Package 2 is the CFD Work Package in which existing CFD codes will be applied to complete helicopter configurations in a blind-test and a post-test exercise. The wind tunnel experiments will be carried out in Work Package 3. The configuration to be investigated in the DNW LLF will be a Mach-scaled model of a modern transport helicopter consisting of the main rotor (R=2.1m), the fuselage (including all control surfaces) and the tail rotor. In order to keep the costs of the experimental campaign as low as possible, existing components will be reused. This will mean that the test configuration is not a scaled model for an existing helicopter, but this is not important because the aim is to produce data for CFD validation for any realistic configuration. The experimental set-up will be tailored to serve the needs of the aerodynamic validation for methods based on the unsteady Reynolds-averaged Navier-Stokes equations. Therefore, the 6m x 8m closed test section will be used. Velocity profiles and the turbulent kinetic energy will be measured at the inflow plane in order to define accurate boundary conditions in the CFD simulations. The measurement will comprise global forces of the main rotor and the fuselage, steady and unsteady pressures, transition positions, stream lines, position of flow separation, velocity fields in the wake, vortex trajectories and elastic deformations of the main and tail rotor blades. The data will be used in Work Package 4 for the validation of the CFD methods. Work Package 4 will establish best practice guidelines for the URANS simulation of complete helicopter configurations. Work Package 5 concerns itself with project management and will be responsible for the project exploitation.

Expected results

The main deliverables will be the deeply analysed experimental database for the complete helicopter, the report on the evaluation of the existing CFD URANS methods for complete helicopters, the report on the post-test computations and the best practice guidelines for the application of URANS methods. Since all European helicopter manufacturers apply CFD methods that have been and are being developed by one of the research centres or universities of the GOAHEAD consortium, the validation of these URANS methods will directly improve the industrial design processes.