Heat Transfer on Iced Cylinders

Abstract

The convective heat transfer is the main mechanism to remove the solidification enthalpy during glaze ice accretion. Most of the airfoil icing prediction codes use a heat transfer calculation procedure based on the classical integral evaluation of the boundary layer. These icing codes consider a smooth surface in laminar regime, the fully rough surface in turbulent regime and that laminar-turbulent transition occurs abruptly without a transition region. This work presents the classical integral evaluation of the boundary layer and proposes the use of an intermittency function to represent the laminar-turbulent region. The present model is used to calculate the local heat transfer coefficient for a rough cylinder and the results are compared with experimental data and with numerical simulations of other authors. The discrepancies between the present results and the experimental data are analyzed and it is shown that an adequate calculation of the convective heat transfer requires that both equivalent sand grain roughness height and rough Stanton number shall represent the characteristics of the rough surface and it is desirable that they are determined experimentally to each type of surface.

Modeling of Ice Accretion over Aircraft Wings Using a Compressible OpenFOAM Solver

“…where μ t is the turbulent viscosity, Pr t is the turbulent Prandtl number, C f is the rough skin friction, U τ is the shear velocity, and K s is the equivalent sand-grain roughness. a, b, and C are defined by Stefanini et al [16] as three constants as -0.45, -0.8, and 1.42, respectively.…”

Proposed Wall Function Models for Heat Transfer around a Cylinder with Rough Surface in Cross Flow

“…The objective of the present paper is to propose momentum and thermal wall functions to estimate the local friction and heat transfer distribution around a rough cylinder in cross flow for Re = 2.2 • 10 5 with pyramidal roughness of equivalent height of K s = 0.00135 m by means of CFD numerical tools. The CFD results generated herein are compared to the heat transfer experimental data of Achenbach [8] and the integral analysis results of Stefanini et al [13]. As required, the paper discusses the improvements obtained with proposed wall functions, the numerical convergence aspects and the experimental data limitations.…”

“…The present paper used the CFD++ version 10.5 provided by Metacomp Technologies in beta testing version, which has the Stefanini et al [13] heat transfer option available. On the other hand, the OF version was the 1.6-ext, which is the version extended and maintained by INTERNET community of the official version 1.7.1 released by OpenCFD.…”

“…Where the St k is given by Eq. (6) and constants a = −0.45, b = −0.8 and C = 1.42 as defined by Stefanini et al [13] for closed-packed pyramidal roughness that Makkonen [2] considered to be similar to icing surfaces. In oder to calculate C f in OpenFOAM solver, the following equations were employed:…”

“…This approach was criticized by Pimenta [12] because one parameter is used to represent three independent roughness characteristics: height, distribution and shape. Recently, Stefanini et al [13] proved that it is necessary to use two parameters in order to represent Achenbach's closed-packed pyramidal roughness [8] by Owen's St k correlation [14]. Therefore, there is a clear advantage to use a laboratory controled experiment with a precise definition of K s [8] in the validation of the heat transfer prediction of integral or differential icing simulation codes.…”