An improved CFD approach for ice-accretion prediction using the discrete element roughness method

Ice-shape prediction results are shown wherein DiscreteElement Roughness Method (DERM)-based CFD solutions are coupled with LEWICE to supplement the built-in heat transfer prediction module. This coupling produces multi-step ice-shape predictions. The effect of using the newer roughness-height distribution model of Han and Palacios rather than the roughnessheight prediction of LEWICE is also gauged. DERM is used in an attempt to improve heat transfer predictions beyond the capability of a sand-grain-roughness model while only slightly increasing the computation time. LEWICE is the industry-standard ice growth prediction tool maintained by NASA. LEWICE is known to predict ice shapes very accurately within its validation envelope, but suffers lowered accuracy for icing conditions in the glaze regime. The predictions that result from the DERMLEWICE coupling are compared with ice shapes generated in experiments from the Penn State Adverse Environment Rotor Test Stand (AERTS). It is observed that ice-shape predictions in the glaze-icing regime can be highly sensitive to the convective heattransfer predictions.