Small towing tank for accurate testing of significantly scaled-down ship models

• Main Author: Chung, Hau Kim.
• Other Authors: Ng Yin Kwee
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Maritime studies::Maritime science and technology
• Online Access: http://hdl.handle.net/10356/50072
• Institution: Nanyang Technological University

In the project, the author will verify the results of a scaled model using Computational Fluid Dynamics (CFD) with the measured resistance of the exact same model in a towing tank. An investigation will also be conducted on how grid resolution and value of y+ will affect the accuracy of the computed results. Literature review on dimensional analysis and the different types of resistance that are encountered by ships was carried out. The dilemma between satisfying Froude and Reynolds number and how a final compromise was achieved is described. The three turbulent models that were used for computation and their governing equations are subsequently detailed. A previous concept of using bubbles to reduce resistance which has gained traction with the maritime industry recently is outlined with fresh technologies explained. A preliminary investigation was first carried out on the submerged part on a ship hull to gain an understanding on the FLUENT solver package. Subsequent variation of grid resolution and y+ was examined and determine how accuracy can be improved. Three different turbulent models of k-ε, k-w and Spalart-Allmaras were used to compute the total resistance of the scaled model. The computation results are compared against towing tank data in term of surface flow pattern, mean velocity field and drag. The results show that both two equation models k-ε and k-w provided commendable agreement with experimental data. Flow simulation was completed on the full ship model using the surface capturing approach with the resistance predicted. Variation of grid resolution on accuracy will be explored.