The Application of Combined Momentum – Blade Element Theory for Aerodynamics Analysis Helicopter Rotor Blade in the Forward Flight

Abstract

Present work introduced the aerodynamics analysis of rotor blade helicopter in forward flight. The analysis used a combination between a Momentum Theory and The Blade Element Theory. Here the inflow ratio was assumed a uniform over the disk plane and it was predicted by using the momentum Theory. As the inflow ratio is available, then by using the Blade element theory, the aerodynamics loading along the blade span of the rotor are computed, which finally the thrust coefficient CT can be obtained. For a given a rotor blade configuration and flight condition, the Thrust coefficient CT is unknown, while the momentum theory required this value to be known in predicting the inflow ratio. As result an iteration process is required in implementing those two combined approaches. For the assessment purposes, four test cases had been studied. The difference between one case to other case had been selected in term: 1) twist distribution, 2) the presence of coning angle and 3) the required aerodynamics characteristics. The result showed that the combination of Momentum Theory and The blade element theory could provide a fast solution in predicting the aerodynamics performance of rotor blade helicopter. However a comparison result with the experiment result was required in order to asses the degree of accuracy of this approach. This was suggested as future work.