MARITIME AFTERNOON HYDRAULICS Torben Ole Andersen June 14, 2017 Aalborg University, Denmark
Agenda Marine Propellers Digital Hydraulics in a Hydraulic Winch Secondary Control in of Multi -Chamber Cylinders Cylinders Optimal Selection of Drive Trains Slide 2
Related research areas Modelling of vessel dynamics Modelling of crane dynamics Coupled dynamics (large crane, small vessel, heavy payloads) Design controllers for the interconnected systems -To compensate for vessel motions in poor sea environment (crane control) -To compensate for effects of heavy lifting operations (vessel control) -Coordination between vessel control and the crane control Implement and test in simulation and experiment. Objective: increase the performance of the crane and vessel, and ensure the safety of operations Slide 3
Marine propellers Fixed Pitch Propeller Controllable Pitch Propeller Slide 4
Slide 5 Marine propellers
Marine propellers Model scale CFD simulation of single screw hull. Slide 6
Slide 7 Marine propellers
Marine propellers CFD simulation of 4-blade propeller in non-uniform wake field. Propeller Diameter: 5.4 meter Rotational speed: 121 rpm Slide 8
Marine propellers Problems due to the propeller operating in a non -uniform wake field: Transient cavitation Noise Erosion Varying forces and moments on propeller Shaft vibrations Efficiency Pressure pulses Noise Solution: A marine propeller where each blade can pitch individually thereby adapting to local conditions in the wake field. This is called a wake pitching propeller Slide 9
Slide 10 Principle of wake pitching propeller
Challenges in realizing the wake pitching propeller Determine a design procedure for the blades accounting for the blade motion (Not included in the project). Determine the hydrodynamic loads on the blade due to the non - uniform wake field and the blade motion. Determine an optimum pitch trajectory for the blade accounting for the power consumed during the pitching motion and the power saved in propeller efficiency. Design an individual pitching mechanism that is able to pitch the blades such that they follow the optimum pitch trajectory. Slide 11
Digital hydraulics Motivation Variable displacement bent axis pump Variable displacement digital hydraulic pump Slide 12
Digital pump/motor technology Variable displacement Radial piston motor Variable displacement digital hydraulic pump/motor HP LP Slide 13
Digital pump/motor technology Variable displacement Radial piston motor Variable displacement digital hydraulic pump/motor Motor Mode Slide 14 [Power point presentation: Staffa Motor, by Kawasaki Precision Machinery]
Digital pump/motor technology HP LP HP LP Motor Mode Pump Mode Idle Mode Slide 15
Digital pump/motor Development trends Slide 16
Digital pump/motor High torque low speed offshore applications Supply boat 5 Slide 17
Current work Simulation study of a conventional hydraulic and a digital hydraulic winch drive system Parameter winch SWL: 20 000 kg Wire on drum: 3600 m Radius drum: 0.8 m Drive system Case 1: Load: 18000 kg Load velocity: 1 m/s Lifting length : 10 m Load Case 2: Load: 4000 kg Load velocity: 1.5 m/s Lifting length: 10 m x Load Slide 18
Current work Simulation study of a conventional hydraulic and a digital hydraulic winch drive system Assumptions: Constant winch radius Wire uniformly distributed on the drum Drive system Constant mass moment of inertia of drum and wire No friction in drum No elasticity in wire x Load Load Slide 19
Current work Simulation study of a conventional hydraulic and a digital hydraulic winch drive system pa 25 bar Conventional hydraulic winch drive system El Pump pb Gear Gear Load p A Digital hydraulic winch drive system El 25 bar p B Slide 20 Load
Current work Simulation study of a conventional hydraulic and a digital hydraulic winch drive system Conventional system: Motor: 2x250 cc/rev, variable displacement axial piston motor Pump: 500 cc/rev, variable displacement axial piston pump El Pump pa pb 25 bar Gear Gear Pump speed: 1800 rpm Pump and motors are modelled with efficiency given by the manufacturer Load Slide 21
Current work Simulation study of a conventional hydraulic and a digital hydraulic winch drive system Digital system Motor: 42 cylinders radial DHPM Cylinder displacement: 1650 cc/rev El p A 25 bar Pump: 500 cc/rev, variable displacement axial piston pump p B Pump speed: 1800 rpm Load Control strategy DHPM Sequential flow diverting Slide 22
Current work Results Case 1 Conventional hydraulic winch drive system Digital hydraulic winch drive system Efficiency at constant speed: 75% Power loss: 60 kw Efficiency at constant speed: 86% Power loss: 27 kw Slide 23
Current work Results Case 2 Conventional hydraulic winch drive system Digital hydraulic winch drive system Efficiency at constant speed: 59% Power loss: 41 kw Efficiency at constant speed: 70% Power loss: 23 kw Slide 24
Further work Replace the axial piston pump with a digital hydraulic piston pump Investigate on/off valve requirements El p A 25 bar Response time Flow capacity p B Power consumption Prototype building Load p A Master student Sequential flow diverting El 25 bar Partial flow diverting p B Load Slide 25
Classical Cylinder Control Inefficient due to throttling Orifice Equation Where Slide 26
Slide 27 Secondary control of multichamber cylinders
Problems Low speed controllability Pressure pulsations Unknown Reliability Switching Losses Secondary control of multi-chamber cylinders Slide 28
Conclusion Aims of the project Improve Controllability Improve Efficiency Investigate Reliability Interesting avenues of research Improve controllability with parallel valves Large valve to select pressure + Small valve in return line to attenuate pressure Hydraulic Energy Storage Fault Tolerant Control Slide 29
Optimal selection of Drivetrains Introduction Actuation of Offshore Mechatronic Systems Today: Hydraulic actuators are often powered by a central HPU AC motors tend to replace traditionally used hydraulic motors Hydraulic Power Unit Slide 30
Introduction In the future: Self-contained applications (robots) Linear actuators operating free of central HPU Slide 31
Self-contained linear actuators Electromechanical Cylinder Drivetrain Planetary Roller Screw Ball Screw Ref.[4] Slide 32
Self-contained linear actuators Electromechanical Cylinder Drivetrain Hydraulic Cylinder Drivetrain Ref.[4] Ref.[3]
Problem statement Research question: Slide 34
Feasibility study of electromechanical cylinder drivetrain Scope of work: 1. Identify a relevant offshore drilling equipment case study 2. Model the offshore mechatronic case study and analyze the actuation force 3. Identify a suitable commercial off-the-shelf electromechanical cylinder drivetrain 4. Size and select the drivetrain components from manufacturer catalog 5. Model the electro mechanical cylinder drivetrain using catalog data 6. Analyze the feasibility of the drivetrain based on the simulation results Slide 35 and a literature study
Upper beam Case study Upper trolley Vertical pipehandling machine SmartRacker (Cameron Sense) Upper dolly Gripper arm hoisting winch Upper guide arm Auxiliary arm Gripper arm Hydraulic lifting cylinder Support arm Main arm Column Lower guide arm Lower trolley Slide 36 Lower dolly Hydraulic soft stabbing cylinder Gripper head 36 Lower rail
5163 mm Modeling of multibody system Kinematic s 1 3 Inverse dynamics 10 9 8 4 6 5 2 7 3435 mm Slide 37
Modeling of electro mechanical cylinder Drive unit: Field-oriented control PMSM modeled the rotating dq-frame Slide 38
Modeling of electro mechanical cylinder Transmission system Forward dynamics Slide 39
Feasibility Analysis Literature study Advantages: good energy-efficiency, simple installation, low maintenance, high accuracy high static load capabilities. relatively compact and can offer high power-to-weight ratios eliminates fluid spills. Slide 40
Feasibility Analysis Disadvantages: low durability at high load force due to wear little overload protection against shock loads safe operation and reliability is not tested offshore redundancy is limited in case of jamming of the screw. Slide 41 41
MARITIME AFTERNOON HYDRAULICS