Performance degradation of propeller systems due to rime ice accretion

Abstract

A theoretical ice accretion model has been established applicable to both aircraft propellers and helicopter rotors to determine the effect of rime ice on the thrust, power, and efficiency as a function of exposure time in a natural icing condition. Comparisons have been made of theoretical performance levels with previously published experimentally determined propeller thrust and efficiency for five natural icing conditions. Agreement between test and theory was acceptable. Nomenclatureefficiency h,t = blade thickness / = drag constant, Eq. (1) J = advance ratio = V/nD k/c = roughness height, Eq. (1) LWC = liquid water content n = revolutions per second q^ = freestream dynamic pressure = l/zp^ V 2r = local radius R -radius Vi = induced velocity V^tU = freestream velocity x = airfoil chord location y = airfoil thickness location a = angle of attack (3 = blade twist angle; droplet impingement efficiency i^max = maximum droplet impingement efficiency At = icing time r/ = propeller efficiency = (C T / C p ) // p ice =• ice density p^ = freestream density

Computational Prediction of Propeller Performance in Icing Conditions

“…More recently, Korkan et al 7 developed a theoretical model for analyzing propeller performance and were able to obtain good agreement with published experimental data. Another analytical model, an enhanced strip method, was developed by Miller et al 8 This code used Bragg's 2-D droplet trajectory code 9 to calculate the accumulation parameter and collection efficiency, and empirical correlations of Gray, 10 Bragg,9 and Flemming 11 to determine the effect of ice accretion on blade section performance.…”

Three dimensional droplet trajectory code for propellers of arbitrary geometry

“…Virtually all previous efforts to computationally predict the impingement efficiency and limits of impingement of supercooled water droplets on propellers and rotor blades are based on the classical propeller strip analysis such as the work done by Korkan et al 1 . 2 > 3 .…”

Helicopter flight characteristics in icing conditions

“…Rotor blade ice accretion, which primarily affects rotor blade aerodynamic characteristics, degrades performance and flying qualities and can pose a threat to flight safety. Within the past 30 years, researchers have drawn upon experimental and theoretical research involving fixed-wing and propeller icing to investigate the potentially hazardous effects of ice accretion on rotor blades (1)(2)(3)(4)(5)(6) . Korkan et al (5)(6)(7) and Flemming et al (8,9) initially studied rotorcraft icing problems, but only as regards the effects of icing on rotor blade aerodynamics and rotor torque.…”