Study on the effect of the descent rate of a helicopter in the Vortex Ring conditions

• Autorzy: Surmacz K. , Kowaleczko G.

Identyfikatory

DOI

10.5604/12314005.1213538

• Języki publikacji: EN

Abstrakty

EN

One of the limiting factors for a helicopter operation is the Vortex Ring State (VRS). This aerodynamic phenomenon, known as the VRS or “Settling with Power”, is characterized by the formation of circulating air stream moving along a ring shaped track around the main rotor of a helicopter. Conditions, conducive to development of the vortex ring state, occur in the vertical or nearly vertical descent. This leads to decrease in thrust and thus rapidly increasing the rate of descent. This phenomenon occurs for an appropriate combination of induced velocity and the velocity of the stream of airflow from the bottom to the rotor. The rates of change of velocities delimit dangerous areas of flight. The objective of this work was to investigate the influence of the descent rate of a helicopter on the vortex ring formation process and determinants of the occurrence of vortex rings. For better understanding of the nature of this state, a computational method was applied. Series of three-dimensional (3D) unsteady analysis was carried out using Computational Fluid Dynamics tools (CFD). Simulations were realized using geometry and performance of the W-3 “Sokol” helicopter. The paper presents results of a helicopter operation in axial and non-axial descent conditions. Three calculation cases of vertical flight of a helicopter with different rates of velocity changes were considered. A simulation of non-axial descent was based on the measured flight test data for the W-3 helicopter. The results provide information about the changing nature of the flow in the course of the movement of a helicopter and show the influence of the rate of descent during initiation on the development of VRS. Results of the calculations provide guidelines for helicopter pilots.

Słowa kluczowe

EN

Vortex Ring State; helicopter descent; computational fluid dynamics; flow simulations

• Wydawca: Łukasiewicz Research Network - Institute of Aviation ; European Science Society of Powertrain and Transport KONES Poland ; Wydawnictwo Instytutu Technicznego Wojsk Lotniczych
• Czasopismo: Journal of KONES
• Rocznik: 2016
• Tom: Vol. 23, No. 1
• Strony: 345--352
• Opis fizyczny: Bibliogr. 6 poz., rys.

Twórcy

autor

Surmacz K.

• Institute of Aviation, Department of Aerodynamics Krakowska Avenue 110/114, 02-256 Warsaw, Poland tel.: [phone], fax: [phone]

autor

Kowaleczko G.

• Air Institute of Technology Księcia Bolesława Street 6, 01-494 Warsaw, Poland tel.: [phone], fax: [phone]

Bibliografia

• [1] Grzegorczyk, K., An analysis of vortex ring state on the rotorcraft, Transactions of the Institute of Aviation, Vol. 6(201), pp. 52-66, Warsaw 2009.
• [2] Johnson, W., Model for vortex ring state influence on rotorcraft flight dynamics, NASA, TP-2005-213477, California 2005.
• [3] Juriew, B.N., Aerodynamics of propellers and helicopters, WMON, Moscow 1956.
• [4] Pegg, J., An investigation of the helicopter height-velocity diagram showing effects of density altitude and gross weight, NASA, TN D-4536, 1968.
• [5] Seddon, J., Basic helicopter aerodynamics, BSP Professional Books, Oxford 1990.
• [6] Stanisławski, J., Prediction of helicopter H-V zone and cueing the emergency maneuver after power loss, The Archive of Mechanical Engineering, Vol. LVII, pp. 21-44, 2010.

Uwagi

PL

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę.