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L.J.G. Huijgens

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5 records found

Hardware in the loop experiments with ship propulsion systems in the towing tank

Scale effects, corrections and demonstration

Journal article - L.J.G. Huijgens, A. Vrijdag, J.J. Hopman

Standards for environmental impact, safety and operational performance of ships are becoming increasingly strict. In order to meet these standards, the performance of new ship designs must be predicted with an increasing level of detail and confidence. As present prediction metho ...

Propeller-engine interaction in a dynamic model scale environment

Conference paper - L.J.G. Huijgens, A. Vrijdag, J.J. Hopman

Regulatory demands on ship designs, such as emission and manoeuvrability requirements, are becoming increasingly stringent, raising the need for advanced methods to predict and assess dynamic propulsion plant behaviour of a new design. At present, model scale experiments and nume ...

Hardware in the Loop Emulation of Ship Propulsion Systems at Model Scale

Doctoral thesis - L.J.G. Huijgens

Requirements on ships are rapidly increasing. In particular, safety and environmental impact are under increasing scrutiny. At the same time, cost and profitability remain as important as they have ever been. These increasingly stringent constraints are beginning to pose problems during the design process. For example, the energy efficiency design index (EEDI) aims to reduce emissions of carbon dioxide by progressively limiting engine power installed on board. However, these reductions in propulsive power raise concerns about the ship's manoeuvrability in rough seas. Moreover, the expected introduction of novel power and propulsion systems based on, for example, fuel cell technology, further raises uncertainty regarding the performance of future ships and propulsion systems in dynamic environments. Considering these developments, detailed predictions of manoeuvrability and propulsion plant behaviour are becoming increasingly important in the ship design process. Yet, present prediction methods are insu_cient to evaluate manoeuvrability and behaviour of ship propulsion systems in complex, dynamic environments such as heavy seas. Fully numerical methods based on computational fluid dynamics (CFD) and first principles are inherently uncertain and compute-intensive. As such, these methods are presently unsuitable to assess the dynamic interaction between machinery and hydrodynamics over prolonged periods of time. As an alternative to numerical methods, experiments with scale model ships can be conducted. However, such experiments are subject to hydrodynamic scale effects: viscous friction, spray formation and propeller cavitation are not the same as at full scale. Moreover, these model ships are powered by considerably simplified propulsion systems, causing entirely different propulsion plant dynamics than at full scale. Ideally, scale model experiments would be conducted with, for example, a perfectly downscaled diesel engine, gearbox and propeller; in practice, however, this is generally not feasible. As such, existing prediction methods leave great uncertainty how future ship designs can simultaneously meet all requirements regarding operational performance, safety and compliance with environmental regulations. A possible way to bridge this knowledge gap is by conducting hardware in the loop (HIL) experiments in the ship model basin. Such experiments combine numerical simulations with a physical test setup. During HIL experiments with free sailing ship models, the propulsion engine and other machinery are simulated by a computer. These simulations are then used to control an electric motor, powering the propeller of a physical scale model ship. As such, the complex interaction between engine, propeller, hull and environment can be physically reproduced, allowing to assess design choices early on in the ship design process. @en

Hardware in the loop experiments on the interaction between a diesel-mechanical propulsion system and a ventilating propeller

Journal article - L.J.G. Huijgens, A. Vrijdag, J.J. Hopman

The interaction between ship propulsion machinery, propellers and the highly dynamic environment which is the sea is a complex yet highly relevant subject. During a storm, for example, waves and ship motions may cause the propeller to draw air, or ventilate, resulting in rapid ch ...

Prediction of work content in shipbuilding projects using extrapolation methods

Conference paper - L.J.G. Huijgens, F Verhelst, J.M.G. Coenen

A method to quantify manufacturing activities for shipbuilding projects is devised, based on extrapolation of historical projects. Extrapolation rules are based on first principles and fine-tuned using empirical data. A 4-tier hierarchical system structure is proposed, incorporat ...

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Experimental and numerical research into propeller thrust breakdown due to ventilation

Master thesis - M. van der Leij, Bart Schuiling, T.J.C. van Terwisga, L.J.G. Huijgens, I. Akkerman, G. Hagesteijn

When propellers are operating near the free surface, phenomenon called ventilation might occur. Due to insufficient immersion and high thrust loading, the propeller draws air, resulting in a reduced thrust. Reduced thrust may have consequences such as loss of propulsive power, control and steerability, and may therefore be leading to safety issues. Long time exposure to ventilation’s unsteady torque loading can also lead to propulsive unit malfunctioning. As propeller diameters tend to grow bigger, free surface clearance decreases and room is left for air to be drawn. To increase understanding of the phenomenon, current experimental and numerical research was executed. The used propeller was a Wageningen C4.55-propeller, an in design condition lightly-loaded propeller with low blade area, fitting to the trend of increasing diameters. The research was bound by perfect conditions to capture ventilation in the purest form; no influences of wake, waves and ship motion were taken into account. Experimental research showed that free surface ventilation appeared to be the most stable and predictable ventilation regime. Inception through free surface breaking mainly depends on the pressure gradient between the propeller tip and free surface, the tip immersion rate and the ability to draw the free surface. Increased ventilation thrust breakdown showed to be influenced by the local velocity on the blade, which mainly depends on the propeller rotation rate. Vortex ventilation was the most unstable regime in the experiments. Inception seems to be independent of the propeller loading, but influenced by local flow phenomena in the area above the propeller and propeller characteristics . It is believed that vortex inception, shape and wash-out resembles the appearance of the cavitating propeller-hull vortex. Vortex ventilation showed a bistability effect. Experimental results were obtained using a statistical research planning/Design of Experiments, such that polynomial models could be constructed. The model fitted the data well, demonstrated by the fitting coefficient r2 exceeding 0.9. Structural shortcomings were found in capturing the highly unsteady vortex ventilation, variations in mixed ventilation and increased thrust breakdown in free surface ventilating. Numerically, ventilation was simulated using the incompressible VoF-solver ReFRESCO. Vortex ventilation inception was not found, even when a scale resolving simulation was conducted. This is ascribed to insufficient application of the SRS-model in the near blade area, due to insufficient convergence of the omega-equation. Also application of Boussinesqs assumption in the k-equation might be stringent. Free surface ventilation inception was accurately found, both in simulations with a for ventilation adapted actuator disk model and with the propeller. Thrust breakdown was underestimated by CFD. Only breakdown due to surface piercing was found. Underestimation is ascribed to the absence of air entrainment. Application of TNT-EARSM-model (which is not using Boussinesqs assumption) and application of free-slip boundary conditions did not improve the shortcoming. As in literature, other free surface discretization schemes showed the same lack of air engtrainment, the origin might be in the VoF-assumption, being the increased interpolated density used in the momentum equation which prevents air to be convected.