Chris Michael Langel

University of California, Davis | UCD · Department of Mechanical and Aerospace Engineering

Leading edge erosion and roughness accumulation is an issue observed with great variability by wind plant operators, but with little understanding of the effect on wind turbine performance. In wind tunnels, airfoil models are typically tested with standard grit roughness and trip tape to simulate the effects of roughness and erosion observed in fie...

A comparison between several different transition prediction methodologies is presented as applied to high Reynolds number flows. A brief overview of the theoretical foundation of various strategies is given and some example implementations are provided. The focus of the current study is on the e N envelope method of XFOIL and a correlation based γ...

A study has been conducted to improve the correlations within a computational rough-ness amplification model implemented in the unsteady RANS solver OVERFLOW-2. The model extends the Langtry-Menter transition model by introducing an additional scalar field roughness amplification quantity, Ar. This additional variable and transport equation allows...

Over time it has been reported wind turbine power output can diminish below man-ufacturers promised levels. This is clearly undesirable from an operator standpoint, and can also put pressure on turbine companies to make up the difference. A likely explana-tion for the discrepancy in power output is the contamination of the leading edge due to envir...

A surface roughness model extending the Langtry-Menter transition model has been implemented in a RANS framework. The model, originally proposed by Dassler, Kozulovic, and Fiala, introduces an additional scalar field roughness amplification quantity. This value is explicitly set at rough wall boundaries using surface roughness parameters and local...

Wind farm operators observe power production decay over time, with the exact cause unknown and dificult to quantify. A likely explanation is blade surface roughness, as wind turbines are continuously subjected to environmental hazards. Dificulty arises in understanding and quantifying performance degradation. Historically, wind turbine airfoil fami...