Accurate prediction of the rotor and fuselage interaction is essential for the design and analysis of modern rotorcrafts. Computational simulation plays an important role in decreasing expensive wind tunnel experiments. In this research, a method for simulating the helicopter flow field has investigated. In this method, rotor is not modelled as a rotating body; instead, its time-averaged effect is added to momentum equations and the force that rotor exerted on the fluid is replaced by source terms in momentum equations. The source terms, are distributed over computational cells in three ways: uniform, linear and by means of blade element theory. Wind tunnel experiments on a generic rotor and helicopter fuselage performed by NASA. The flow field over this fuselage is simulated in two advance ratios and three thrust coefficients. The pressure coefficients obtained by various distributions of source terms are compared with experimental data. Uniform and linear distributions are found to be inaccurate. By means of the blade element theory and trimming pitch angles, pressure coefficients are predicted more accurately. Also, the variation of simulated thrust of rotor in respect of its power is similar to actual rotor. The model helicopter is mounted over a strut. The presence of strut in the computational domain has not important effect on results for low speed free streams; but in high speeds, the presence of strut results in better prediction of forces and pressure coefficients over body especially downstream of strut.
