Hydrodynamic design of high pull ROV
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- Institutt for marin teknikk 
This paper is a study of the design of a ROV with high pull force. The focus is the hydrodynamic design, but several other aspects had to be included to set feasible boundaries for the hydrodynamic design. The work is divided in three parts. The first focuses on general design, setting limits for power supply and pull force and discussing general arrangements and stability. The second part focuses on propeller design, describing different applicable methods and starts the design of a propeller for a high pull ROV. The third part puts the results together and presents a temporary ROV design and presents the solutions. This part also includes discussion of the work and suggestions for further work. The first part, General design, completes a feasibility study by concluding that a reasonable maximum pull force for a high pull ROV is approximately 82 tonnes at a maximum operational depth of 800 meters. Here estimations of power-thrust relations are made and limitations regarding power flow and physical size are discussed. A ducted contra-rotating propeller is considered suitable considering the ROV’s main goal. Further two systems for manoeuvring are suggested. One system for manoeuvring in loaded condition and one for manoeuvring in unloaded condition is presented and assumed feasible and adequate. The general arrangement, including positioning and weights of the main components of the ROV, has been proposed with a solution resulting in neutral buoyancy and a stable submerged ROV. External shape and resistance have been discussed. The total resistance of a streamlined ROV is estimated to approximately 4 tonnes. Issues concerning practical handling of the ROV have been mentioned. The second part, Propeller design, attempts a design of a ducted contra-rotating propeller. First different aspects considering propeller design is described and special concerns regarding design of a ducted contra-rotating propeller are discussed. A thorough review of the program AKPA which is used for the propeller design is given. The process of making the propeller design of a ducte contra-rotating propeller has been started, but due to some difficulties it has not been completed. The third part of the paper presents the work done and the ROV design made. The result is a ROV with a pull force of 77.8 tonnes, a total dry weight of 114 tonnes, an overall length of 18.8 meters and a propeller diameter of 5 meters. The necessary power supply is 2.2 MW delivered to the ROV. Several aspects of this design are still uncertain and needs further exploration. The propeller design should be completed and especially structural concerns and power supply should be taken into account. Stability and external shape could be explored further, particularly stability in floating condition and during surface operations.