Showing papers on "Glaze ice published in 2014"

A feasibility study to identify ice types by measuring attenuation of ultrasonic waves for aircraft icing detection

Abstract: Aircraft icing has been recognized as the most significant weather hazard that impacts aviation safety. A thin sheet of ice on lifting or control surfaces of an aircraft can adversely affect its flight performance by increasing drag and decreasing lift and thrust. The uncontrolled shedding of ice built up on surfaces may severely damage critical components. The occurrence of ice accretion is also a big challenge in terms of economic impact. The presence of ice can not only cause flight delays, but also reduce flight profits by increasing fuel consumptions and additional cost for de-icing operations. A better understanding of the physical mechanisms of water movement and the ice formation process on aircraft surfaces is very important and critical in ensuring safe and efficient operation of aircraft in cold weather. Generally there are two types of ice that can be deposited during flight: glaze ice and rime ice, which occur is dependent on weather conditions. Glaze ice is formed with high liquid water content (LWC) and large droplet size at temperatures just below the freezing point, and it has a smooth, clear and dense appearance. Rime ice forms with lower LWC and smaller droplet size at temperatures around or below −12 C°. It is a mixture of tiny ice particles, containing many micro bubbles and cracks, and it has a white rough appearance. These two types of ice may have significantly different effects on flight performance. However, most of the current de-icing approaches and practices do not consider this and operators potentially perform a lot of unnecessary actions. In this study, attenuation measurement of ultrasonic waves is performed to investigate the feasibility of characterization of ice types. Analysis investigates frequency dependent attenuation properties that are potentially closely related to ice acoustic properties and hence the micro-structure.Copyright © 2014 by ASME

Robust Surface Evolution and Mesh Deformation for Three Dimensional Aircraft Icing Applications on a Swept GLC-305 Airfoil

Abstract: This paper presents the application of a mesh generation strategy for problems involving deforming geometries produced by three-dimensional ice accretion simulations, which are more challenging than corresponding two-dimensional problems. A technique to deform a discrete surface as it evolves due to the accretion of ice is described. The surface evolution algorithm is based on a face-offseting approach. A fast algebraic technique to propagate the computed surface deformations into the surrounding volume mesh while maintaining geometric mesh quality is also presented. Results are presented for a complex glaze ice on a rectangular planform wing with a constant GLC-305 airfoil section and rime ice and glaze shapes on a swept, tapered GLC-305 wing also with a GLC-305 cross section.

Entrained Film of Ice–Water Slurry with Impinging Supercooled Water Droplets

Abstract: Hitting cold surfaces, such as aircraft ones, supercooled water droplets may freeze immediately. However, glaze ice may also be formed under some conditions: a part of the droplets may freeze, while the rest remains liquid, fl owing on the substrate as a fi lm. This paper proposes a model of a fi lm created by the impact of supercooled droplets on a cylindrical obstacle. The fi lm is a mixture of water and frazil ice, viz. a slurry. The fi lm thickness and volume fraction of ice in the water are expressed by simple analytical formulas obtained from the mass and enthalpy balance laws in the presence of different phenomena responsible for fi lm cooling. The results are compared with the data of existing experiments.

Computational Aerodynamic Analysis of Three-Dimensional Ice Shapes on a NACA 23012 Airfoil

Abstract: The present study identifies a process for performing computational fluid dynamic calculations of the flow over full three-dimensional (3D) representations of complex ice shapes deposited on aircraft surfaces. Rime and glaze icing geometries formed on a NACA23012 airfoil were obtained during testing in the NASA Glenn Research Center's Icing Research Tunnel (IRT). The ice shape geometries were scanned as a cloud of data points using a 3D laser scanner. The data point clouds were meshed using Geomagic software to create highly accurate models of the ice surface. The surface data was imported into Pointwise grid generation software to create the CFD surface and volume grids. It was determined that generating grids in Pointwise for complex 3D icing geometries was possible using various techniques that depended on the ice shape. Computations of the flow fields over these ice shapes were performed using the NASA National Combustion Code (NCC). Results for a rime ice shape for angle of attack conditions ranging from 0 to 10 degrees and for freestream Mach numbers of 0.10 and 0.18 are presented. For validation of the computational results, comparisons were made to test results from rapid-prototype models of the selected ice accretion shapes, obtained from a separate study in a subsonic wind tunnel at the University of Illinois at Urbana-Champaign. The computational and experimental results were compared for values of pressure coefficient and lift. Initial results show fairly good agreement for rime ice accretion simulations across the range of conditions examined. The glaze ice results are promising but require some further examination.

Анализ статистических данных о результатах работы систем мониторинга гололедообразования

Abstract: In article the analysis of data on results of work of gravitational system of glaze ice monitoring of STGN is made. The analysis is made for two parallel air lines 110 kV, on one of which STGN post is established. In article the analysis of data on results of work of gravitational system of monitoring of icing of STGN is made. The analysis is made for two parallel VL-110 lines of kV of PO KES of «Volgogradenergo» (the V area on ice), on one of which STGN post is established. Installation of a post of system of STGN changes a ratio of refusals of lines. Installation of one post of STGN allows to reduce number of refusals by 3,6 times. The analysis of data on electric power losses is made at swimming trunks. It is revealed that the STGN installation raises costs of melting by 7 times (≈7,4 times). According to statistical data only 65% of swimming trunks for STGN of the line are successful. Completely it is impossible to exclude unsuccessful swimming trunks because of late detection of ice and complexity of determination of intensity of icing. For increase of reliability of the line it is necessary to know the moment of the beginning of formation of deposits, to know intensity of increase and the greatest possible mass of deposits, to be able to predict dynamics of process. It becomes possible if the ice weight, and the conditions leading to its emergence are traced not. Within this concept the system of monitoring of intensity of icing «МИГ». Natural tests «МИГ» are carried out in networks of JSC «Volgogradenergo». The «МИГ» system allows to define the moment of the beginning of education, a look, the greatest possible mass of glaze ice and intensity of its increase in real time. Besides, the system allows to control wire temperature at heating and melting of ice, line overloads in summertime, predicts change of intensity of icing.

Thermodynamic Method of Glaze Ice Monitoring on Air Lines Wires

Abstract: In article the new principles of creation of system of glaze monitoring are offered. Icing process is considered as a thermodynamic wire surface process.

Icing Collection Efficiency Prediction Using an Eulerian-Eulerian Approach

Abstract: A collection efficiency model using an Eulerian-Eulerian approach is implemented within CFD++, the commercial CFD code from Metacomp Technologies, in which a finite volume scheme is employed to discretize the droplet and gas flows. The continuous phase and droplet governing equations are solved in a coupled fashion with the appropriate momentum and energy transfer between the phases. CFD simulations have been performed assuming various droplet diameters and distributions in order to validate icing collection efficiencies on engines, airfoils and glaze ice shapes. Applications to icing clouds with median volumetric diameters greater than 50 microns which fall outside the Appendix C envelope have also been considered. Supercooled large droplet (SLD) impingements require an extended numerical model to account for droplet rebound and splash mechanisms near solid boundaries. Simulations with SLD modeling have shown that these mechanisms considerably influence impingement predictions.

Computational Aerodynamic Analysis of Three-Dimensional Ice Shapes on a NACA 23012 Airfoil

Abstract: The present study identifies a process for performing computational fluid dynamic calculations of the flow over full three-dimensional (3D) representations of complex ice shapes deposited on aircraft surfaces. Rime and glaze icing geometries formed on a NACA23012 airfoil were obtained during testing in the NASA Glenn Research Centers Icing Research Tunnel (IRT). The ice shape geometries were scanned as a cloud of data points using a 3D laser scanner. The data point clouds were meshed using Geomagic software to create highly accurate models of the ice surface. The surface data was imported into Pointwise grid generation software to create the CFD surface and volume grids. It was determined that generating grids in Pointwise for complex 3D icing geometries was possible using various techniques that depended on the ice shape. Computations of the flow fields over these ice shapes were performed using the NASA National Combustion Code (NCC). Results for a rime ice shape for angle of attack conditions ranging from 0 to 10 degrees and for freestream Mach numbers of 0.10 and 0.18 are presented. For validation of the computational results, comparisons were made to test results from rapid-prototype models of the selected ice accretion shapes, obtained from a separate study in a subsonic wind tunnel at the University of Illinois at Urbana-Champaign. The computational and experimental results were compared for values of pressure coefficient and lift. Initial results show fairly good agreement for rime ice accretion simulations across the range of conditions examined. The glaze ice results are promising but require some further examination.

Experiment on effect of cone angle on ice accretion of rotating spinner

Abstract: Simulated ice accretion tests on four sub-scale rotating spinner models with different cone angles were conducted in icing wind tunnel.The similarity parameters of ice accretion were derived for rotating surface.And the ice accretion test parameters for subscale spinner models were determined according to the matching of important similarity parameters.The ice accretion and final ice shapes were recorded by a high speed video system in the test.The test results show that the ice accreted on these four models is composed of early formed glaze ice which entirely covers the clean surface and subsequent white rime ice which grows rapidly.For the spinner model with cone angle is no larger than 74°,the rime ice appears in the form of needle or grain,which is relatively thinner.For the spinner model with cone angle larger than 80°,the rime ice is feather shaped which is thicker and could be partly shed from the icing surface.The position of shedding for the spinner model with larger cone angle moves downstream.

The application of eulerian two-phase flow method in airfoil ice accretion

Abstract: A numerical simulation method based on Eulerian Two-Phase theory was applied on airfoil under a variety of icing weather conditions. The flow field is calculated by solving the 2D N-S equations with cell-centered finite volume method. The Rime ice, Glaze ice and mixed ice were predicted on NACA0012 airfoil at 4 degree angle of attack. The simulated results agree very well with the refered experiment data, which indicates that the method is effective and correct.At last the aerodynamic characteristics of the iced airfoil was analyzed, compare different ice shape on the lift and drag coefficient, the results show that the Glaze ice has the most impact on aerodynamic characteristics.