EC145 Helicopter Fuselage
The numerical simulation of the complete helicopter with rotating rotors, soft blades and flight attitude trimming is only a very recent achievement, which cannot be yet considered as part of the industrial analysis and design processes. Instead, computing isolated components is nowadays standard, e.g. the isolated main rotor in hover or forward flight with or without soft blades and trim, or the isolated fuselage. As to the latter, there are enough challenges to legitimate a dedicated study on that “simplified” configuration.
The geometry is that of a wind tunnel model of the EC145 helicopter fuselage including a support strut mounted underneath, for which a wind tunnel measurement campaign has been sub- contracted to the University of Munich (figure left). The test conditions were zero angle of incidence and side-slip along with Mach and Reynolds numbers of Ma = 0.11 and Re = 2.3 106 per meter. The measured data includes: global forces and moments; surface static and unsteady pressures; field velocities on six windows in the backdoor wake; and, finally, the transition line from laminar to turbulent boundary layer regime.
University of Munich
University of Berlin
This apparently simple configuration proves in fact to bear in it many challenging flow-field aspects: among others a massive flow separation on the backdoor and a von Karman street behind the support strut. For instance, capturing correctly the backdoor separation and the associated wake allows better predicting the drag force and the interactions with the rear control surfaces, both important for fuel consumption reduction and stability respectively.
This industry relevant test-case provides a means of measuring whether a given turbulence modelling technique can supply meaningful results within acceptable turn around times. To be particular investigated are models of the RSM, DES (figure right) and SAS families.
Assessment of computational results will deal with steady and unsteady quantities corresponding to the measured ones.