Showing papers on "Glaze ice published in 1999"
28 Jun 1999
TL;DR: In this article, the effect of simulated ice shape geometry on airfoil aerodynamic performance was investigated using a wind tunnel test with a flapped NLF( l)-0414 airframe where aerodynamic parameters including hinge moment were measured.
Abstract: A systematic study of the effect of simulated ice shape geometry on airfoil aerodynamics was performed. A wind tunnel test was performed using a flapped NLF( l)-0414 airfoil where aerodynamic parameters including hinge moment were measured. The ice shapes tested were designed to simulate a single glaze ice horn with leading-edge radius, size and airfoil surface location varied. In all nine ice simulations were tested at six different leading edge locations. The objective of this research was to determine the sensitivity of iced airfoil aerodynamics to ice shape geometry. Configurations were also tested at three different Reynolds numbers (0.5, 1.0, and 1.8~10~). It was determined that ice horn leading-edge radius had only a small effect on airfoil aerodynamics. However, the aerodynamic performance was very sensitive to ice shape size and location. An almost linear relationship between loss in maximum lift and ice horn location was found with the largest loss at the furthest location back on the upper surface. Reynolds number was found to have little effect on the aerodynamic results on the airfoil with simulated ice shapes.
51 citations
11 Jan 1999
TL;DR: In this article, a series of tests were made in the NASA Glenn Icing Research Tunnel to determine how icing scaling results were affected by the choice of scale velocity and the resulting scale velocities ranged from 85 to 220 percent of the reference velocity.
Abstract: A series of tests were made in the NASA Glenn Icing Research Tunnel to determine how icing scaling results were affected by the choice of scale velocity. Reference tests were performed with a 53.3-cm-chord NACA 0012 airfoil model, while scale tests used a 27.7-cm-chord 0012 model. Tests were made with rime, mixed, and glaze ice. Reference test conditions included airspeeds of 67 and 89 m/s, an MVD of 40 microns, and LWCs of 0.5 and 0.6 g/cu m. Scale test conditions were established by the modified Ruff (AEDC) scaling method with the scale velocity determined in five ways. The resulting scale velocities ranged from 85 to 220 percent of the reference velocity. This paper presents the ice shapes that resulted from those scale tests and compares them to the reference shapes. It was concluded that for freezing fractions greater than 0.8 as well as for a freezing fraction of 0.3, the value of the scale velocity had no effect on how well the scale ice shape simulated the reference shape. For freezing fractions of 0.5 and 0.7, the simulation of the reference shape appeared to improve as the scale velocity increased.
30 citations
TL;DR: In this article, the authors presented results of the ice accretion tests performed to validate the hybrid airfoil design method, which was developed to facilitate the design of hybrid aerodynamic models with full-scale leading edges and redesigned aft sections.
Abstract: This paper presents results of the ice accretion tests performed to validate the hybrid airfoil design method The hybrid airfoil design method was developed to facilitate the design of hybrid airfoils with full-scale leading edges and redesigned aft sections that simulate full-scale ice accretion simulation for a given ® range Icing tests in the NASA Lewis Icing Research Tunnel were conducted with test conditions representative of e ight A twodimensional half-scale hybrid airfoil was designed and built with a 20% plain e ap and a 5% upper and 20% lower full-scale leading-edge surface of a modern business jet wing section This paper presents a comparison between the ice shapes accreted on the business jet and hybrid airfoil models during the tests The test results show that ice accretion simulation could be predicted in terms of the droplet-impingement simulation alone and cone rm the assumption that the leading-edge ice accretion will be the same for the full-scale and hybrid airfoils if icing cloud properties, droplet impingement, local leading-edge e owe eld, model surface characteristics, and geometry are held constant This assumption was found to be valid when tested under the most severe conditions of glaze ice accretion over a large time interval A comparison between the actual ice shapes and those predicted by LEWICE 16 under similar conditions is also shown The results suggest that the hybrid airfoil design method has signie cant application potential for tests where leading-edge ice accretion is desired because it provides an alternative to the myriad of issues related to ice accretion scaling
27 citations
01 Jun 1999
TL;DR: In this article, the effect of velocity and sweep angle on the critical distance in ice accretion formation on swept wings at glaze ice conditions was studied on a NACA 00 1 2 swept wing tip at velocities of 75, 100, 150, and 200 miles per hour.
Abstract: An experiment was conducted to study the effect of velocity and sweep angle on the critical distance in ice accretion formation on swept wings at glaze ice conditions. The critical distance is defined as the distance from the attachment line to the beginning of the zone where roughness elements develop into glaze ice feathers. Icing runs were performed on a NACA 00 1 2 swept wing tip at velocities of 75, 100, 150, and 200 miles per hour. At each velocity and tunnel condition, the sweep angle was changed from 0 deg to 45 deg at 5 deg increments. Casting data, ice shape tracings, and close-up photographic data were obtained. The results showed that at given velocity and tunnel conditions, as the sweep angle is increased from 0 deg to 25 deg the critical distance slowly decreases. As the sweep angle is increased past 25 deg, the critical distance starts decreasing more rapidly. For 75 and 100 mph it reaches a value of 0 millimeters at 35 deg. For 150 and 200 mph it reaches a value of 0 millimeters at 40 deg. On the ice accretion, as the sweep angle is increased from 0 deg to 25 deg, the extent of the attachment line zone slowly decreases. In the glaze ice feathers zone, the angle that the preferred direction of growth of the feathers makes with respect to the attachment line direction increases. But overall, the ice accretions remain similar to the 0 deg sweep angle case. As the sweep angle is increased above 25 deg, the extent of the attachment line zone decreases rapidly and complete scallops form at 35 deg sweep angle for 75 and 100 mph, and at 40 deg for 150 and 200 mph.
19 citations
TL;DR: In this paper, an analytical model is developed for the prediction of glaze ice accretion with runback water for electric power lines including the Joule heating effect, which is coupled with the liquid film flow by slip (non-zero velocity) boundary conditions a the liquid-air interface.
Abstract: An analytical model is developed for the prediction of glaze ice accretion with runback water for electric power lines including the Joule heating effect. In this model, the external air flow is coupled with the liquid film flow by slip (non-zero velocity) boundary conditions a the liquid-air interface. In this way, corrections to previous rime ice models are given in order to account for runback water and its effect on wet ice growth in freezing rain conditions with ambient temperatures slightly below 0[°C]. Also, the process of Joule heating in icing conditions is examined from a thermodynamic optimization viewpoint in a manner which permits efficient power transmission while dissipating heat in order to reduce ice accumulation. Good agreement is achieved between theoretical predictions of the glaze ice accretion and experimental results from the freezing rain simulator at the University of Manitoba.
10 citations