“…Table 4 shows all cases studied in this paper. 13 In total, 31 cases are selected. Cases 1 vary LWC in a rime condition with a temperature of À20°C.…”
Section: Resultsmentioning
confidence: 99%
“…LEWICE predictions show excellent agreement for cases X and Y. Although the ice horn size on the lower side of case Z is under-predicted, the key characteristics of the ice shapes are well captured including the upper and lower horns.Figure 6.LEWICE ice accretion shape validations against the experiment 13,28 : (a) case X, (b) case Y, and (c) case Z.…”
Section: Validationmentioning
confidence: 88%
“…First, Benchmark Problems for Airframe Noise Computations (BANC) cases studied by Herr et al 25 are replicated to validate airfoil trailing-edge noise predictions. Then, the experimentally obtained ice shapes presented in the article by Son et al 13 are used to validate LEWICE ice accretion models. Lastly, the work of Bragg et al 26 is replicated to validate CFD predictions of pressure and flow fields as well as boundary layer parameters on an iced airfoil.…”
Trailing-edge noise is known to be sensitive to airfoil shapes, and ice accretion is one cause of an airfoil shape deformation. This paper investigates how trailing-edge noise is affected by the airfoil shape deformation due to ice accretion. The formation of ice-induced flow separation and the development of a turbulent boundary layer are analyzed to understand the correlation between the altered flow physics due to ice accretion inside the boundary layer and trailing-edge noise. The near-wall flow behind the leading-edge ice accretion is analyzed by using Reynolds-Averaged Navier Stokes CFD in OpenFOAM, and trailing-edge noise is investigated using an empirical wall pressure spectrum model in conjunction with Amiet’s trailing-edge noise theory. Validations of tools against measurement data are presented. Liquid water content, freestream velocity, and ambient temperature are varied to investigate the impact of flow conditions on the ice accretion shape and the resulting boundary layer flow characteristics at the trailing edge. It is found that a more significant leading edge deformation due to ice accretion generates larger ice-induced flow separation bubbles, which increases the trailing-edge boundary layer thickness. As a result, an increase in low- and mid-frequency noise is observed. The purpose of this paper is not only to understand the effect of ice accretion on trailing-edge noise but also to comprehensively analyze how flow physics inside the turbulent boundary layer is altered by the presence of various ice accretion shapes.
“…Table 4 shows all cases studied in this paper. 13 In total, 31 cases are selected. Cases 1 vary LWC in a rime condition with a temperature of À20°C.…”
Section: Resultsmentioning
confidence: 99%
“…LEWICE predictions show excellent agreement for cases X and Y. Although the ice horn size on the lower side of case Z is under-predicted, the key characteristics of the ice shapes are well captured including the upper and lower horns.Figure 6.LEWICE ice accretion shape validations against the experiment 13,28 : (a) case X, (b) case Y, and (c) case Z.…”
Section: Validationmentioning
confidence: 88%
“…First, Benchmark Problems for Airframe Noise Computations (BANC) cases studied by Herr et al 25 are replicated to validate airfoil trailing-edge noise predictions. Then, the experimentally obtained ice shapes presented in the article by Son et al 13 are used to validate LEWICE ice accretion models. Lastly, the work of Bragg et al 26 is replicated to validate CFD predictions of pressure and flow fields as well as boundary layer parameters on an iced airfoil.…”
Trailing-edge noise is known to be sensitive to airfoil shapes, and ice accretion is one cause of an airfoil shape deformation. This paper investigates how trailing-edge noise is affected by the airfoil shape deformation due to ice accretion. The formation of ice-induced flow separation and the development of a turbulent boundary layer are analyzed to understand the correlation between the altered flow physics due to ice accretion inside the boundary layer and trailing-edge noise. The near-wall flow behind the leading-edge ice accretion is analyzed by using Reynolds-Averaged Navier Stokes CFD in OpenFOAM, and trailing-edge noise is investigated using an empirical wall pressure spectrum model in conjunction with Amiet’s trailing-edge noise theory. Validations of tools against measurement data are presented. Liquid water content, freestream velocity, and ambient temperature are varied to investigate the impact of flow conditions on the ice accretion shape and the resulting boundary layer flow characteristics at the trailing edge. It is found that a more significant leading edge deformation due to ice accretion generates larger ice-induced flow separation bubbles, which increases the trailing-edge boundary layer thickness. As a result, an increase in low- and mid-frequency noise is observed. The purpose of this paper is not only to understand the effect of ice accretion on trailing-edge noise but also to comprehensively analyze how flow physics inside the turbulent boundary layer is altered by the presence of various ice accretion shapes.
“…For the upper surface in Fig. 8(i), large icing limits appear in the right-hand (11,12,10,18,19,20) and left-hand (13, 21) clusters, and upper clusters (4,5,7) have larger values than lower ones. For the lower surface, as the values are negative, a lower value denotes a larger limit of accretion.…”
Section: Eqs (15) and (16)mentioning
confidence: 94%
“…10), which compares the ice accretion shapes achieved by various methods and icing wind tunnel tests under the conditions. The code predicts ice accretion shapes as accurately as other numerical codes under both the rime and glaze conditions.…”
Section: Calculation Of Ice Accretion Shapesmentioning
The relationship between the ice accretion shape and ambient conditions is quantitatively investigated via analysis of variance (ANOVA) and is qualitatively studied using self-organization maps (SOMs). The independent variables of this study are liquid water contents (LWC), mean volumetric droplet diameter (MVD), flight speed (free stream velocity) and ambient temperature. The ranges of these variables follow appendix C of FAR part 25. The ice accretion shape is quantified through parameterization of ice accretion area, maximum thickness, ice heading and icing limits. SOMs and ANOVA can be used for parameter analysis. We determine the associated parameters, although the parameters are examined under non-linear conditions. The range of temperature, À40-0 C, is divided into 10 C intervals. Three distinctive temperature groups are found, depending on the response of the ice shape to the ambient conditions. They are rime (À40-À20 C), mixture (À20-À10 C) and glaze (À10-0 C). The ice accretion area and maximum thickness are determined by free stream velocity and LWC over the entire temperature range, while ice heading is affected by the temperature, free stream velocity and LWC. Different variables affect the icing limits on the upper and lower surfaces. On the upper surface, runback dominates the formation of icing, while on the lower surface the dominant factor is where limits are impinged.
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