Prediction of Helicopter H-V Zone and Cueing the Emergency Maneuver After Power Loss

Stanisławski, Jarosław

doi:10.2478/v10180-010-0002-2

Cited by 2 publications

(2 citation statements)

References 3 publications

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“…Helicopter flight technique particularly determines the existence of combination of height-velocity, which should be avoided for safety. The H-V diagram [4,6] provides information on this subject. The H-V zones are also known as the dead man's curves and define the range of potentially dangerous values of flight velocity and height.…”

Section: Boundaries For Low Speed Helicopter Flightmentioning

confidence: 99%

Study on the Effect of the Descent Rate of a Helicopter in the Vortex Ring Conditions

Surmacz

Kowaleczko

2016

Journal of KONES. Powertrain and Transport

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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.

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Section: Boundaries For Low Speed Helicopter Flightmentioning

confidence: 99%

Study on the Effect of the Descent Rate of a Helicopter in the Vortex Ring Conditions

Surmacz

Kowaleczko

2016

Journal of KONES. Powertrain and Transport

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“…Many authors, e.g. Johnson (2005), Ignatkin et al (2018) and Stanisławski (2010), are focused only on investigations of flight of isolated main rotor, and their computational models of flight are based usually on implemented the nonlinear blade vortex model. Based on the same approach, Ignatkin et al (2018) present the computational research on aerodynamic performance of the Mi-8 helicopter main rotor in the hover state and the vertical descent state, including VRSs.…”

Section: Introductionmentioning

confidence: 99%

Investigations of the vortex ring state on a helicopter main rotor using the URANS solver

Stalewski

Surmacz

2020

AEAT

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Purpose This paper aims to present the novel methodology of computational simulation of a helicopter flight, developed especially to investigate the vortex ring state (VRS) – a dangerous phenomenon that may occur in helicopter vertical or steep descent. Therefore, the methodology has to enable modelling of fast manoeuvres of a helicopter such as the entrance in and safe escape from the VRS. The additional purpose of the paper is to discuss the results of conducted simulations of such manoeuvres. Design/methodology/approach The developed methodology joins several methods of computational fluid dynamics and flight dynamic. The approach consists of calculation of aerodynamic forces acting on rotorcraft, by solution of the unsteady Reynold-averaged Navier–Stokes (URANS) equations using the finite volume method. In parallel, the equations of motion of the helicopter and the fluid–structure-interaction equations are solved. To reduce computational costs, the flow effects caused by rotating blades are modelled using a simplified approach based on the virtual blade model. Findings The developed methodology of computational simulation of fast manoeuvres of a helicopter may be a valuable and reliable tool, useful when investigating the VRS. The presented results of conducted simulations of helicopter manoeuvres qualitatively comply with both the results of known experimental studies and flight tests. Research limitations/implications The continuation of the presented research will primarily include quantitative validation of the developed methodology, with respect to well-documented flight tests of real helicopters. Practical implications The VRS is a very dangerous phenomenon that usually causes a sudden decrease of rotor thrust, an increase of the descent rate, deterioration of manoeuvrability and deficit of power. Because of this, it is difficult and risky to test the VRS during the real flight tests. Therefore, the reliable computer simulations performed using the developed methodology can significantly contribute to increase helicopter flight safety. Originality/value The paper presents the innovative and original methodology for simulating fast helicopter manoeuvres, distinguished by the original approach to flight control as well as the fact that the aerodynamic forces acting on the rotorcraft are calculated during the simulation based on the solution of URANS equations.

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Prediction of Helicopter H-V Zone and Cueing the Emergency Maneuver After Power Loss

Cited by 2 publications

References 3 publications

Study on the Effect of the Descent Rate of a Helicopter in the Vortex Ring Conditions

Study on the Effect of the Descent Rate of a Helicopter in the Vortex Ring Conditions

Investigations of the vortex ring state on a helicopter main rotor using the URANS solver

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