RESEARCH OF THE HIGH HARMONICS INDIVIDUAL BLADE CONTROL EFFECT ON VIBRATIONS CAUSED BY THE HELICOPTER MAIN ROTOR THRUST

The paper presents numerical results analysis of main rotor vibration due to helicopter main rotor thrust pulsation.The calculation method, the object of research and numerical research results with the aim to reduce the amplitude of the vibrations transmitted to the hub from the helicopters main rotor by the individual blade control in azimuth by the installation angle of blades cyclic changes are set out in the article. The individual blades control law for a five-blade main rotor based on the blade frequencies is made. It allows reducing the vibration from thrust. Research takes into account the main rotor including and excluding the blade flapping motion. The minimal vibrations regime is identified.Numerical study of variable loads caused by unsteady flow around the main rotor blades at high relative speeds of flight, which transmitted to the rotor hub, is made. The scheme of a thin lifting surface and the rotor vortex theory are used for simulation of the aerodynamic loads on blades. Non - uniform loads caused by the thrust, decomposed on the blade harmonic and its overtones. The largest values of deviation from the mean amplitude thrust are received. The analysis of variable loads with a traditional control system is made. Algorithms of higher harmonics individual blade control capable of reducing the thrust pulsation under the average value of thrust are developed.Numerical research shows that individual blade control of high harmonics reduces variable loads. The necessary change in the blade installation is about ± 0,2 degree that corresponds to the maximum displacement of the additional con- trol stick is about 1 mm.To receive the overall picture is necessary to consider all six components of forces and moments. Control law with own constants will obtained for each of them. It is supposed, that each of six individual blade control laws have an impact on other components. Thus, the problem reduces to the optimization issue. The individual blade control general law will be received as a result. It will meet a lot of conflicting requirements.

helicopter, main rotor, individual blade control, aerodynamic characteristics, vibration, vortex theory

1. Belotserkovsky S.M., Loktev B.E., Nisht M.I. Issledovanie na JeVM ajerodinamicheskih i ajerouprugih harakteristik vintov vertoletov [Aerodynamic and elastic characteristics of helicopter`s rotor research on computer]. Moscow. Mashinostroenie [Industrial Engineering]. 1992. 218 p.

2. Kritsky B.S. Matematicheskaya model' aerodinamiki vintokrylogo letatel'nogo apparata [Mathematical aerodynamics model of rotorcraft fly vehicle]. Trudy TsAGI [Papers of TsAGI], 2002, no. 2655, pp. 50–56. (in Russian)

3. Belotserkovsky S.M., Kotovsky V.N., Nisht M.I., Fedorov R.M. Matematicheskoe modelirovanie ploskoparallel'nogo otryvnogo obtekanija tel [Mathematical modeling of plane separated flow on bodies]. Moscow. Nauka [Science publ]. 1988. 231 p.

4. Golovkin V.A., Kritsky B.S., Mirgazov R.M. Programma raschjota ajerodinamicheskih harakteristik skorostnyh nesushhih vintov vertoljotov razlichnyh shem (Gr_Vega_V1.1). Svidetel'stvo gosudarstvennoj registracii programmy dlja JeVM № 2013661689 ot 12 dekabrja 2013 g. [The program of calculation of aerodynamic characteristics of high-speed rotors of helicopters of various schemes (Gr_Vega_V1.1). Certificate of state registration of the computer program no. 2013661689 on December 12, 2013]. (in Russian)

5. http://sdelanounas.ru/blogs/79097/ (accessed 30.05.2016).

6. http://fcp.economy.gov.ru/cgi-bin/cis/fcp.cgi/Fcp/ViewFinDoc?fcp=124&fin=92&year=2013 (accessed 2.06.2016).

7. http://bastion-karpenko.ru/v-37_psv/ (accessed 2.06.20).

8. http://zhukvesti.ru/articles/detail/34377/ (accessed 8.06.2016).

9. http://www.tehnoomsk.ru/node/1910 (accessed 8.06.2016).

10. Kritsky B.S., Mirgazov R.M. Programma raschjota vibroperegruzki, vyzvannoj pul'saciej sily tjagi nesushhego vinta s individual'nym upravleniem lopastjami po vysokim garmonikam (RC_VTOL_Vibration). Svidetel'stvo gosudarstvennoj registracii programmy dlja JeVM № 20166118851 ot 9 avgusta 2016 g. [Abnormal vibration calculation program caused by ripple traction of rotor blades individually controlled by high harmonics (RC_VTOL_Vibration). Certificate of state registration of the computer program no. 20166118851 on August 9, 2016]. (in Russian)