Main rotor vibration overload caused by thrust pulsation analytical studies based on vortex theory

Аuthors

Animitsa V. A.^*, Borisov A. E.^*, Kritsky B. S.^**, Mirgazov R. M.^***

Central Aerohydrodynamic Institute named after N.E. Zhukovsky (TsAGI), 1, Zhukovsky str., Zhukovsky, Moscow Region, 140180, Russia

*e-mail: spintest@tsagi.ru
**e-mail: boris.kritsky@tsagi.ru
***e-mail: ruslan.mirgazov@tsagi

Abstract

The paper presents the results of numerical study of the impact of the main rotor blades individual control by their pitch angle cyclic variation to reduce thrust pulsations transferred to the main rotor hub, resulting in negative effect of the helicopter structural elements, crew and passengers. The study consists in developing the methodology and mathematical model of blades azimuthal control at blade frequency and its overtones.

The authors carried out numerical studies of the thrust variable loads caused by non-stationary flow around main rotor blades transferred to the rotor hub at higher relative flight speeds. The thin lifting surface scheme was used to model the flow through the blades process. The authors performed an analysis of varying loads and educed the amplitudes of their deviation from the conventionally controlled main rotor thrust without higher harmonics control. Rotor blade pitch higher harmonics control algorithms were developed, which allow reduce thrust the main rotor pulsations at thrust average value.

Computational studies showed that rotor blade higher harmonics control allows reduce the level of variable loads. The required blade setting variation herewith comes up to ±0.2 degrees, which conforms to maximum additional displacement of the control rod realized in practice with the value of about 1 mm.

Keywords:

vortex theory, helicopter rotor, variable load, vibro g-load, control algorithms

References

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