Md
M.R. de Graaf
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Image processing for hydrofoil strut ventilation at moderate Froude number
A data driven approach to calmwater flow ventilation for vertical hydrofoil struts
Submerged ship propellers, superventilating torpedoes, and rudders on displacement and planing vessels. This research focuses on the natural ventilation of a hydrofoil strut at a yaw angle at a moderate Froude number. In such cases, air from the free surface flows towards the suction side of the hydrofoil.
A methodology was developed to extract physically meaningful features from high-speed imagery obtained during towing tank experiments. The framework combines unsupervised clustering techniques with image processing algorithms for geometric reconstruction.
It is demonstrated that the points on the hydrofoil free surface can be reconstructed algorithmically using an implementation of the Hough Gradient Method. These points have been successfully used to fit an asymmetric sigmoid function to the free surface contour. A modified implementation of the Hough Gradient Method, with adjustments to improve image contrast, enables reconstruction of the cavity closure angle. While unsupervised clustering methods show partial correspondence with known flow regimes, the results indicate that more advanced techniques are required for reliable, generalizable classification.
An additional contribution is the identification of an observable difference in free surface contour for a specific ventilation mechanism. Specifically, cases associated with a Laminar Separation Bubble exhibit a more forward free surface drawdown and a steeper depth gradient compared to other ventilation mechanisms. These findings demonstrate the potential of automated visual analysis not only for post-processing but also for advancing the physical understanding of hydrofoil ventilation. ...
A methodology was developed to extract physically meaningful features from high-speed imagery obtained during towing tank experiments. The framework combines unsupervised clustering techniques with image processing algorithms for geometric reconstruction.
It is demonstrated that the points on the hydrofoil free surface can be reconstructed algorithmically using an implementation of the Hough Gradient Method. These points have been successfully used to fit an asymmetric sigmoid function to the free surface contour. A modified implementation of the Hough Gradient Method, with adjustments to improve image contrast, enables reconstruction of the cavity closure angle. While unsupervised clustering methods show partial correspondence with known flow regimes, the results indicate that more advanced techniques are required for reliable, generalizable classification.
An additional contribution is the identification of an observable difference in free surface contour for a specific ventilation mechanism. Specifically, cases associated with a Laminar Separation Bubble exhibit a more forward free surface drawdown and a steeper depth gradient compared to other ventilation mechanisms. These findings demonstrate the potential of automated visual analysis not only for post-processing but also for advancing the physical understanding of hydrofoil ventilation. ...
Submerged ship propellers, superventilating torpedoes, and rudders on displacement and planing vessels. This research focuses on the natural ventilation of a hydrofoil strut at a yaw angle at a moderate Froude number. In such cases, air from the free surface flows towards the suction side of the hydrofoil.
A methodology was developed to extract physically meaningful features from high-speed imagery obtained during towing tank experiments. The framework combines unsupervised clustering techniques with image processing algorithms for geometric reconstruction.
It is demonstrated that the points on the hydrofoil free surface can be reconstructed algorithmically using an implementation of the Hough Gradient Method. These points have been successfully used to fit an asymmetric sigmoid function to the free surface contour. A modified implementation of the Hough Gradient Method, with adjustments to improve image contrast, enables reconstruction of the cavity closure angle. While unsupervised clustering methods show partial correspondence with known flow regimes, the results indicate that more advanced techniques are required for reliable, generalizable classification.
An additional contribution is the identification of an observable difference in free surface contour for a specific ventilation mechanism. Specifically, cases associated with a Laminar Separation Bubble exhibit a more forward free surface drawdown and a steeper depth gradient compared to other ventilation mechanisms. These findings demonstrate the potential of automated visual analysis not only for post-processing but also for advancing the physical understanding of hydrofoil ventilation.
A methodology was developed to extract physically meaningful features from high-speed imagery obtained during towing tank experiments. The framework combines unsupervised clustering techniques with image processing algorithms for geometric reconstruction.
It is demonstrated that the points on the hydrofoil free surface can be reconstructed algorithmically using an implementation of the Hough Gradient Method. These points have been successfully used to fit an asymmetric sigmoid function to the free surface contour. A modified implementation of the Hough Gradient Method, with adjustments to improve image contrast, enables reconstruction of the cavity closure angle. While unsupervised clustering methods show partial correspondence with known flow regimes, the results indicate that more advanced techniques are required for reliable, generalizable classification.
An additional contribution is the identification of an observable difference in free surface contour for a specific ventilation mechanism. Specifically, cases associated with a Laminar Separation Bubble exhibit a more forward free surface drawdown and a steeper depth gradient compared to other ventilation mechanisms. These findings demonstrate the potential of automated visual analysis not only for post-processing but also for advancing the physical understanding of hydrofoil ventilation.