Prediction Of Impact Pressures Forces And Moments During Vertical And Oblique Water Entry

Prediction of Impact Pressures, Forces, and Moments During Vertical and Oblique Water Entry

An engineering tool is described for calculating pressures and loads at high-speed water entry which is simple to use, inexpensive to exercise and applicable to a wide variety of geometries. A simplified potential model is used which replaces the water's free surface with an effective planar surface that is positioned using an empirical parameter available in the literature for a wide variety of shapes. To confirm predictions, calculations are compared to experiment for the oblique water entry of spheres, cones, disks, and cusps. Surface pressures agree well with measurement reflecting both the model geometry and location on the model. The calculated drag and lift exhibit close agreement with experimental values, particularly prior to the peak loads. At later times the shape of the hydraulic cavity must be taken into account and an approximate procedure for doing this is described. A computer code listing and sample computer runs are provided as well as instructions for using the code.

Correlation of Instantaneous Impact Drag Coefficients for Vertical Water Entry

Prediction of Impact Pressures, Forces, and Moments During Vertical and Oblique Water Entry