Further Insight into the Hydrodynamic Phenomena Influencing Motions, Dynamics Loads and Performance of High Speed Craft in a Seaway
Abstract
The flow field around a High-Speed Craft (HSC) is complicated; the hull acts as a lifting surface causing unique flow phenomena and loads. The main hydrodynamic engineering challenges for HSC are to increase the performance, decrease accelerations, and decrease damaging slamming forces. These challenges are commonly addressed through either experimental methods (towing tank testing or in situ free running testing) or empirical/analytical and numerical models. Empirical methods have limitations in their accuracy, and numerical models for HSC are not yet as accurate as their counterparts for displacement hulls. The reason is that many of the physical phenomenarelated to planing craft, are not yet fully understood.In this project, model scale in situ free running testing will be used to shed light on some key flow mechanisms underlying the hydrodynamics associated with High Speed Craft advancing in calm water and rough seas. The target phenomena have been chosen based on identified knowledge gaps, the closing of which is required to further develop numerical models to a higher degree ofapplicability to HSC. This project will investigate how flow separation effects calm water resistance, running position, added resistance and acceleration in waves but also how slamming and global bending moment relates to hull rigidity.We have previously found that forcing separation to happen using spray deflectors/rails can improve calm water performance but that the location and shape of the spray deflectors is paramount. For optimal detachment, correct determination of the stagnation line is required. This is, however, something current state of the art numerical and semi-empirical methods struggle topredict. Accelerations and slamming forces are important measurements of vessel performance in waves and accurate predictions of head seas performance will aid in reducing structural weight.Slamming loads are difficult to capture due to their transient behavior; to understand how they affect the hull structure, a segmented backbone beam hull will be tested to quantify global bending moment and local slamming pressure. Comparing the results to a rigid hull fitted with pressure sensors will give insights into the role hull rigidity plays for performance of HSC in rough seas.All datasets will be readily available to the scientific and boat building communities for rapid dissemination of the gained knowledge.In conclusion, the project will contribute to both better design of HSC and a better understanding of the fundamental flow physics around such craft, while also creating validation data sets to further enhance the development of hydrodynamics and fluid-structure interaction models.Ultimately, this project will provide the Navy, numerous private sector stakeholders, and the research community with an improved understanding of factors that affect performance, safety, seaworthiness, and structural integrity of HSC.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 19, 2020
- Source ID
- N000142012855
Entities
People
- Mirjam Furth
Organizations
- Office of Naval Research
- Texas Engineering Experiment Station
- United States Navy