• A comparative study of the velocity and vorticity structure in pipes and boundary layers at friction Reynolds numbers up to 10^4 

      Zimmerman, Spencer; Philip, Jimmy; Monty, Jason P; Talamelli, A.; Marusic, Ivan; Ganapathisubramani, Bharathram; Hearst, R. Jason; Bellani, Gabriele; Baidya, Rio; Samie, Milad; Zheng, X; Dogan, Eda; Mascotelli, Lucia; Klewicki, Joe (Journal article; Peer reviewed, 2019)
      This study presents findings from a first-of-its-kind measurement campaign that includes simultaneous measurements of the full velocity and vorticity vectors in both pipe and boundary layer flows under matched spatial ...
    • Aerodynamics of an airfoil with leading-edge icing 

      Vinnes, Magnus Kyrkjebø; Hearst, R. Jason (Peer reviewed; Journal article, 2021)
      Two super duplex stainless steels (SDSS) with different W content, namely UNS S32750 (W-free) and UNS S39274 (2.1 wt.% W), were tested in simulated crevice corrosion environments to determine the influence of W on their ...
    • A comparison of lab-scale free rotating wind turbines and actuator disks 

      Helvig, Sanne de Jong; Vinnes, Magnus Kyrkjebø; Segalini, Antonio; Worth, Nicholas; Hearst, R. Jason (Peer reviewed; Journal article, 2021)
      Planar particle image velocimetry was conducted upstream and in the near-wake of a lab-scale free-rotating wind turbine model and compared to several actuator disks with the same dimensions. The Reynolds number of the ...
    • Experimental and numerical icing penalties of an S826 airfoil at low Reynolds numbers 

      Hann, Richard; Hearst, R. Jason; Sætran, Lars Roar; Bracchi, Tania (Peer reviewed; Journal article, 2020)
      Most icing research focuses on the high Reynolds number regime and manned aviation. Information on icing at low Reynolds numbers, as it is encountered by wind turbines and unmanned aerial vehicles, is less available, and ...
    • The impact of upstream turbulence on a plane jet 

      Kamruzzaman, Md; Rømcke, Olav; Hearst, R. Jason (Peer reviewed; Journal article, 2021)
      The influence of upstream turbulence on the flow produced by a plane jet is investigated experimentally with hot-wire anemometry and smoke flow visualisation. An innovative active grid, where each wing can be independently ...
    • The influence of freestream turbulence on the temporal pressure distribution and lift of an airfoil 

      Li, Leon; Hearst, R. Jason (Journal article; Peer reviewed, 2021)
      To gain insight on how freestream turbulence (FST) affects the aerodynamics of an airfoil in a systematic manner, the present study investigates a NREL S826 airfoil subjected to seven different incoming flows with varying ...
    • Performance and wake of a Savonius vertical‐axis wind turbine under different incoming conditions 

      Aliferis, Alexander D; Jessen, Marius Stette; Bracchi, Tania; Hearst, R. Jason (Journal article; Peer reviewed, 2019)
      In this study, the performance, drag, and horizontal midplane wake characteristics of a vertical‐axis Savonius wind turbine are investigated experimentally. The turbine is drag driven and has a helical configuration, with ...
    • PIV of the Flow Over a NREL S826 Airfoil Subjected to Different Ice Accretions 

      Vinnes, Magnus Kyrkjebø; Li, Leon; Hearst, R. Jason (Chapter, 2019)
      . The results have been compared to previously acquired force measurements. For streamlined ice accretions, increased surface roughness and changes to the combined airfoil-ice geometry lead to reduced aerodynamical performance ...
    • Response of the temporal turbulent boundary layer to decaying free-stream turbulence 

      Kozul, Melissa; Hearst, R. Jason; Monty, Jason P; Ganapathisubramani, Bharathram; Chung, Daniel (Peer reviewed; Journal article, 2020)
      The turbulent boundary layer developing under a turbulence-laden free stream isnumerically investigated using the temporal boundary layer framework. This studyfocuses on the interaction between the ...
    • Robust features of a turbulent boundary layer subjected to high-intensity free-stream turbulence 

      Hearst, R. Jason; Dogan, Eda; Ganapathisubramani, Bharathram (Journal article; Peer reviewed, 2018)
      The influence of the large scale organisation of free-stream turbulence on a turbulent boundary layer is investigated experimentally in a wind tunnel through hot-wire measurements. An active grid is used to generate ...
    • The significant impact of ribs and small-scale roughness on cylinder drag crisis 

      Skeide, Arne Kilvik; Bardal, Lars Morten; Oggiano, Luca; Hearst, R. Jason (Peer reviewed; Journal article, 2020)
      The impact of flow-normal ribs and small-scale surface roughness on the drag and vortex shedding of a circular cylinder was investigated. Three rib heights, four relative rib spacings and three different forms of microroughness ...
    • Simultaneous skin friction and velocity measurements in high Reynolds number pipe and boundary layer flows 

      Baidya, Rio; Baars, W. J.; Zimmerman, Spencer; Samie, Milad; Hearst, R. Jason; Dogan, Eda; Mascotelli, Lucia; Zheng, X; Bellani, Gabriele; Talamelli, A.; Ganapathisubramani, Bharathram; Hutchins, Nicholas; Marusic, Ivan; Klewicki, Joe; Monty, Jason P (Book, 2019)
      Streamwise velocity and wall-shear stress are acquired simultaneously with a hot-wire and an array of azimuthal/spanwise-spaced skin friction sensors in large-scale pipe and boundary layer flow facilities at high Reynolds ...
    • Spatial characteristics of a zero-pressure-gradient turbulent boundary layer in the presence of free-stream turbulence 

      Dogan, Eda; Hearst, R. Jason; Hanson, Ronald; Ganapathisubramani, Bharathram (Journal article; Peer reviewed, 2019)
      Particle image velocimetry (PIV) measurements are performed to examine the structural organization inside a turbulent boundary layer under the influence of free-stream turbulence (FST). In particular, streamwise-wall-normal ...
    • The Mean Velocity of the Near-Field of a Lab-Scale Wind Turbine in Tailored Turbulent Shear Flows 

      Li, Leon; Hearst, R. Jason; Ganapathisubramani, Bharathram (Chapter, 2019)
      This study investigated the mean velocity of the near-field wake of a lab-scale wind turbine subjected to seven different incoming turbulent shear flows through particle image velocimetry. An active grid was used to generate ...
    • The near-field of a lab-scale wind turbine in tailored turbulent shear flows 

      Li, Leon; Hearst, R. Jason; Ferreira, Manuel A.; Ganapathisubramani, Bharathram (Journal article; Peer reviewed, 2020)
      Real wind turbines experience a wide range of turbulent shear flows that naturally occur within the atmospheric boundary layer, however, these are often difficult to simulate in experiments. An active grid was used to ...
    • The Use of Active Grids in Experimental Facilities 

      Hearst, R. Jason (Chapter, 2019)
      Active grids allow for the turbulence in experimental facilities to be tailored through a broad range of turbulence intensities and Reynolds numbers. This work provides an overview of the active grids that presently exist ...
    • Time evolution of uniform moment zones in a turbulent boundary layer 

      Laskari, Angeliki; de Kat, Roeland; Hearst, R. Jason; Ganapathisubramani, Bharathram (Journal article; Peer reviewed, 2018)
      Time-resolved planar particle image velocimetry (PIV) was used to analyse the structuring of a turbulent boundary layer into uniform momentum zones (UMZs). The instantaneous peak detection method employed by Adrian et al. ...