Performance degradation of helicopter rotor in forward flight due toice

Numerical Analysis of Aerodynamic Characteristics of Iced Rotor in Forward Flight

“…Based on the rotor flowfield obtained by CLORNS, the Eulerian method is applied for the simulation of the water droplet field around the rotor. The continuity and momentum equations for droplets around a rotor in 3-D could be simplified as: (5) In the process of supercool droplets movement, there is always a region where no droplets pass through, due to the presence of the blade in their motion path. This region is called the shadow zone or the shadow region, and the apparent density (  ) in the Eulerian method is very low.…”

“…At present, there are few experimental works on the aerodynamic characteristic of iced rotors in the public domain [4][5][6][7]. Korkan [4,5] studied the aerodynamics of helicopter model rotors with attached simulated ice shapes using experiments. Lee [6] also studied iced rotors in a wind tunnel at full scale.…”

Helicopter flight characteristics in icing conditions

“…iced rotor flapping coefficients, deg A,B,C,D plant matrix, control distribution matrix, output matrix, and carry through matrixn, C, C′, ΔC ice-free/iced coefficient, increments of C due to icing g gravitational acceleration, N/kg HE cloud horizontal extent, nmi I helicopter product of inertial, kg/m 2 L, M, N rolling, pitching, and yawing angular acceleration, rad/s 2 LWC liquid water content, g/m 3 n,m station number along the blade-spanwise and azimuthal sector number of the rotor disk MWD median volumetric diameter, μm p, q, r angular rate of helicopter along body x-axis, y-axis, and z-axis, respectively, rad/s q pk peak pitch rate, deg/s r -, M, μ nondimensional of r by rotor radius, and Mach number, and rotor advance ratio T C , T C GL , T C R local temperature, and glaze/rime ice boundary local temperature on blade surface, ºC T S , T GL , T R atmospheric temperature, and glaze/rime ice boundary atmospheric temperature, ºC u, v, w velocity of helicopter along body x-axis, y-axis, and z-axis, ms -1 ut , up relative wind velocity from forward flight and upward flapping at blade section w 1 . 5 index of vertical axis control power, ms -1 X, Y, Z linear acceleration in the body x-axis, y-axis, and z-axis direction, m/s 2 X,Y,U state vector, output vector, and input vector X . helicopter velocity along inertial x-axis, knots α aerofoil angle-of-attack, deg δ control deflection, cm Δθ pk , Δθ min pitch attitude change, and minimum pitch attitude change, deg γ air , r T ratio of specific heats, and boundary-layer recovery factor θ, φ, ψ pitching, rolling, and yawing attitude angle, deg σ, γ rotor solidity, and rotor blade lock number τ icing time, min Ω rotor rotational speed, rad/s ψ, β, β′ rotor blade azimuth angle, and ice-free/iced flapping angle, deg Subscripts L, D lift, and drag T, Y, H, Q rotor thrust, side-force, horizontal force, and rotor torque Max, 0 maximum value, and trim condition B,C, S, R longitudinal, collective, lateral, and directional control stick xz, xx, zz xz-plane, x-axis, and z-axis…”

Numerical simulation for three-dimensional rotor icing in forward flight

“…Therefore, icing will seriously threaten the flight safety of helicopter and even lead to the casualties and property loss. 1,2 Icing phenomenon will occur on the windward surface of helicopter components such as main rotor, tail rotor, windshield, and engine inlet. Rotor is the most critical component of helicopter, and its icing is more serious than other parts.…”