Search

Wave-to-Wire models play an important role in the development of wave energy converters. They could provide insight into the complete operating process of wave energy converters, from the power absorption stage to the power conversion stage. In order to cover a set of relevant nonlinear effects, wave-to-wire models are predominately established in the time domain. However, the low computational efficiency of time-domain modeling is hindering the extensive application of wave-to-wire models, especially in early-stage design and optimization where a large number of iterations are required. To address this issue, a spectral-domain wave-to-wire model is proposed, and the nonlinear effects are incorporated by stochastic linearization. This model can significantly reduce the computational load and maintain good accuracy. The reference concept studied in this paper is defined as a heaving point absorber coupled with a linear permanent-magnet generator. Four representative nonlinear effects involved in both the hydrodynamic stage and the electrical stage of the concept are considered. The proposed model is verified against a corresponding nonlinear time-domain wave-to-wire model, and a good agreement is observed. The relative error of the proposed spectral-domain wave-to-wire model is around 2 % in typical operational regions and is still within 7 % for wave states with large significant wave heights, regarding the estimate of the power conversion efficiency. Meanwhile, the computational load of the spectral-domain wave-to-wire model is reduced by 2 to 3 orders of magnitudes compared with the conventional time-domain approach. Finally, a case study of tuning the PTO damping to maximize power production is conducted to demonstrate the performance of the proposed spectral-domain wave-to-wire model., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Offshore and Dredging Engineering, Transport Engineering and Logistics

An adjustable draft point absorber was recently proposed as a novel approach to improve power absorption with constrained power take-off (PTO) capacities. The key feature of the novel wave energy converter (WEC) concept is to adjust the buoy draft by regulating the ballast water inside the buoy, which aims to enable variation of the natural frequency of the WEC. Although previous research has shown benefits for the energy absorption stage, the impact of the draft adjustment on the power conversion efficiency and overall performance has not been examined yet. Therefore, a wave-to-wire model is established to provide an in-depth insight into the systematic performance of the adjustable draft point absorber integrated with a linear permanent magnet generator. Both a nonlinear hydrodynamic model and an analytical generator model are derived, thus the complete process from the wave power input through the whole WEC system to the usable electricity is covered. Based on the established model, wave-to-wire responses of the novel concept are obtained and analyzed. The negative effects of the draft adjustment on the stroke and overlap between the stator and translator are demonstrated. Moreover, a comparison is made between this novel WEC and conventional fixed draft WEC, and both regular and irregular wave states are considered. The results show that the adjustable draft system could increase not only the absorbed power but also the generator conversion efficiency. In specific conditions, the delivered electrical power of the adjustable draft WEC was over 20 % and 10 % higher than a traditional fixed draft system for regular and irregular waves respectively., Offshore and Dredging Engineering, Transport Engineering and Logistics

The Power Take-Off (PTO) rating of Wave Energy Converters (WECs) is generally much higher than the average extracted power. Scientific literature has indicated that downsizing the PTO capacity to a suitable level is beneficial for improving the techno-economic competitiveness. In this paper, a novel design, namely the adjustable draft system, is proposed for point absorbers to implement PTO downsizing. A frequency domain model is established to calculate the performance of the proposed device. From frequency domain analysis, two potential advantages are identified by installing the adjustable draft system. Firstly, the excitation force can be controlled by adjusting the buoy draft, which could be utilized to reduce the required PTO force. This is helpful for downsizing the PTO capacity. Secondly, the relevant natural frequency of the point absorber can be adapted to the operating wave states by varying the buoy draft, which improves the power absorption. A nonlinear approach is adopted specifically for the spherical buoy to include the nonlinear Froude–Krylov force and viscous drag force. The results show that the nonlinear forces have a significant influence on the power absorption when operating close to resonance regions. However, the advantages resulting from the proposed system still can be observed while considering the nonlinear forces. The power absorption can be improved by 27% and 12% in particular cases of regular and irregular wave states respectively., Offshore and Dredging Engineering, Transport Engineering and Logistics

The power take-off (PTO) system is a main component in wave energy converters (WECs), and it accounts for a notable proportion in the total cost. Sizing the PTO capacity has been proven to be significant to the cost-effectiveness of WECs. In the numerical modeling, the PTO size is normally represented by a force constraint. Therefore, to accurately evaluate the power performance of WECs with various PTO sizes, it is necessary to take the PTO force limitation, a nonlinear effect, into consideration. In this paper, a computationally-efficient spectral domain model of the PTO force saturation is developed for a heaving point absorber, and the nonlinear term is included by statistical linearization. For comparison, a frequency domain and nonlinear time domain model are implemented, and the developed spectral model is verified with the results of the nonlinear time domain model. Compared with the frequency domain model, the spectral domain model remarkably reduces the relative errors in predicting the power performance of WECs with force constraints, while the computational demand is much lower than the nonlinear time domain model. Furthermore, a case study is conducted to size the PTO capacity for reducing the levelized cost of energy (LCOE) in a chosen wave site. Three different numerical models are applied respectively. The frequency domain model could lead to a misestimate of the optimal PTO capacity, with a maximum relative error on the prediction of the annual energy production (AEP) of 24%. In contrast, the spectral domain model indicates the same optimal PTO size with the time domain modeling, and its relative errors on the prediction of the AEP are within 4.3%., Offshore and Dredging Engineering, Transport Engineering and Logistics

A crucial part of wave energy converters (WECs) is the power take-off (PTO) mechanism, and PTO sizing has been shown to have a considerable impact on the levelized cost of energy (LCOE). However, as a dominating type of PTO system in WECs, previous research pertinent to PTO sizing did not take modeling and optimization of the linear permanent magnet (PM) generator into consideration. To fill this gap, this paper provides an insight into how PTO sizing affects the performance of linear permanent magnet (PM) generators, and further the techno-economic performance of WECs. To thoroughly reveal the power production of the WEC, both hydrodynamic modeling and generator modeling are incorporated. In addition, three different methods for sizing the linear generator are applied and compared. The effect of the selection of the sizing method on the techno-economic performance of the WEC is identified. Furthermore, to realistically reflect the relevance of PTO sizing, wave resources from three European sea sites are considered in the techno-economic analysis. The dependence of PTO sizing on wave resources is demonstrated., Offshore and Dredging Engineering, Transport Engineering and Logistics

The Power Take-Off (PTO) rating of Wave Energy Converters (WECs) is generally much higher than the average extracted power. Scientific literature has indicated that downsizing the PTO capacity to a suitable level is beneficial for improving the techno-economic competitiveness. In this paper, a novel design, namely the adjustable draft system, is proposed for point absorbers to implement PTO downsizing. A frequency domain model is established to calculate the performance of the proposed device. From frequency domain analysis, two potential advantages are identified by installing the adjustable draft system. Firstly, the excitation force can be controlled by adjusting the buoy draft, which could be utilized to reduce the required PTO force. This is helpful for downsizing the PTO capacity. Secondly, the relevant natural frequency of the point absorber can be adapted to the operating wave states by varying the buoy draft, which improves the power absorption. A nonlinear approach is adopted specifically for the spherical buoy to include the nonlinear Froude–Krylov force and viscous drag force. The results show that the nonlinear forces have a significant influence on the power absorption when operating close to resonance regions. However, the advantages resulting from the proposed system still can be observed while considering the nonlinear forces. The power absorption can be improved by 27% and 12% in particular cases of regular and irregular wave states respectively., Offshore and Dredging Engineering, Transport Engineering and Logistics

The power take-off (PTO) system is a main component in wave energy converters (WECs), and it accounts for a notable proportion in the total cost. Sizing the PTO capacity has been proven to be significant to the cost-effectiveness of WECs. In the numerical modeling, the PTO size is normally represented by a force constraint. Therefore, to accurately evaluate the power performance of WECs with various PTO sizes, it is necessary to take the PTO force limitation, a nonlinear effect, into consideration. In this paper, a computationally-efficient spectral domain model of the PTO force saturation is developed for a heaving point absorber, and the nonlinear term is included by statistical linearization. For comparison, a frequency domain and nonlinear time domain model are implemented, and the developed spectral model is verified with the results of the nonlinear time domain model. Compared with the frequency domain model, the spectral domain model remarkably reduces the relative errors in predicting the power performance of WECs with force constraints, while the computational demand is much lower than the nonlinear time domain model. Furthermore, a case study is conducted to size the PTO capacity for reducing the levelized cost of energy (LCOE) in a chosen wave site. Three different numerical models are applied respectively. The frequency domain model could lead to a misestimate of the optimal PTO capacity, with a maximum relative error on the prediction of the annual energy production (AEP) of 24%. In contrast, the spectral domain model indicates the same optimal PTO size with the time domain modeling, and its relative errors on the prediction of the AEP are within 4.3%., Offshore and Dredging Engineering, Transport Engineering and Logistics

A jet pump is used to transport a variety of working media and is especially suitable for dredged soil transporting. In this study, a three-dimensional numerical study of a jet pump that is used for slurry delivery was carried out. The characteristics of the internal flow field of the mixing chamber with different working parameters were comprehensively analyzed. The results indicate that the pressure of the axial line decreases with increasing flow ratio (ratio of suction flux and inlet flux) while the pressure of the injected slurry shows a downward trend. With the increase in the flow ratio, the pressure ratio (difference between inlet pressure and suction pressure divided by the difference between exit pressure and suction pressure) falls off while the efficiency presents a parabolic distribution. The pressure ratio can be promoted by properly increasing the length of the mixing chamber so that the available efficiency is broadened. When the mixing chamber length is L = 2.5Dn~4.0Dn (Dn is nozzle outlet diameter), the highly efficient area is wide; in particular, when L = 3.5Dn, the jet slurry pump with the highest efficiency of 27.6% has the best performance., Offshore and Dredging Engineering

Downsizing the Power Take-off (PTO) rating has been proven to be beneficial for decreasing the Levelized Cost of Energy (LCOE) of wave energy converters (WECs). However, the linear permanent magnet (PM) generator has not yet been modelled and optimized in detail in previous feasibility studies. This paper extends the study of the PTO downsizing to further investigate the influence of the linear PM generator sizing on a WEC's techno-economic performance. The generator is sized for providing different maximum forces, and the effect of sizing on the generator performance is presented. The efficiency map of the selected linear generator design is applied to evaluate the annual energy production (AEP) and finally identify its influence on the techno-economic performance of a WEC., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Offshore and Dredging Engineering, Transport Engineering and Logistics

Currently, the techno-economic performance of Wave Energy Converters (WECs) is not competitive with other renewable technologies. Size optimization could make a difference. However, the impact of sizing on the techno-economic performance of WECs still remains unclear, especially when sizing of the buoy and Power Take-Off (PTO) are considered collectively. In this paper, an optimization method for the buoy and PTO sizing is proposed for a generic heaving point absorber to reduce the Levelized Cost Of Energy (LCOE). Frequency domain modeling is used to calculate the power absorption of WECs with different buoy and PTO sizes. Force constraints are used to represent the effects of PTO sizing on the absorbed power, in which the passive and reactive control strategy are considered, respectively. A preliminary economic model is established to calculate the cost of WECs. The proposed method is implemented for three realistic sea sites, and the dependence of the optimal size of WECs on wave resources and control strategies is analyzed. The results show that PTO sizing has a limited effect on the buoy size determination, while it can reduce the LCOE by 24% to 31%. Besides, the higher mean wave power density of wave resources does not necessarily correspond to the larger optimal buoy or PTO sizes, but it contributes to the lower LCOE. In addition, the optimal PTO force limit converges at around 0.4 to 0.5 times the maximum required PTO force for the corresponding sea sites. Compared with other methods, this proposed method shows a better potential in sizing and reducing LCOE., Offshore and Dredging Engineering, Transport Engineering and Logistics, Ship Hydromechanics and Structures

Downsizing the Power Take-off (PTO) rating has been proven to be beneficial for decreasing the Levelized Cost of Energy (LCOE) of wave energy converters (WECs). However, the linear permanent magnet (PM) generator has not yet been modelled and optimized in detail in previous feasibility studies. This paper extends the study of the PTO downsizing to further investigate the influence of the linear PM generator sizing on a WEC's techno-economic performance. The generator is sized for providing different maximum forces, and the effect of sizing on the generator performance is presented. The efficiency map of the selected linear generator design is applied to evaluate the annual energy production (AEP) and finally identify its influence on the techno-economic performance of a WEC., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Offshore and Dredging Engineering, Transport Engineering and Logistics

A jet pump is used to transport a variety of working media and is especially suitable for dredged soil transporting. In this study, a three-dimensional numerical study of a jet pump that is used for slurry delivery was carried out. The characteristics of the internal flow field of the mixing chamber with different working parameters were comprehensively analyzed. The results indicate that the pressure of the axial line decreases with increasing flow ratio (ratio of suction flux and inlet flux) while the pressure of the injected slurry shows a downward trend. With the increase in the flow ratio, the pressure ratio (difference between inlet pressure and suction pressure divided by the difference between exit pressure and suction pressure) falls off while the efficiency presents a parabolic distribution. The pressure ratio can be promoted by properly increasing the length of the mixing chamber so that the available efficiency is broadened. When the mixing chamber length is L = 2.5Dn~4.0Dn (Dn is nozzle outlet diameter), the highly efficient area is wide; in particular, when L = 3.5Dn, the jet slurry pump with the highest efficiency of 27.6% has the best performance., Offshore and Dredging Engineering

Currently, the techno-economic performance of Wave Energy Converters (WECs) is not competitive with other renewable technologies. Size optimization could make a difference. However, the impact of sizing on the techno-economic performance of WECs still remains unclear, especially when sizing of the buoy and Power Take-Off (PTO) are considered collectively. In this paper, an optimization method for the buoy and PTO sizing is proposed for a generic heaving point absorber to reduce the Levelized Cost Of Energy (LCOE). Frequency domain modeling is used to calculate the power absorption of WECs with different buoy and PTO sizes. Force constraints are used to represent the effects of PTO sizing on the absorbed power, in which the passive and reactive control strategy are considered, respectively. A preliminary economic model is established to calculate the cost of WECs. The proposed method is implemented for three realistic sea sites, and the dependence of the optimal size of WECs on wave resources and control strategies is analyzed. The results show that PTO sizing has a limited effect on the buoy size determination, while it can reduce the LCOE by 24% to 31%. Besides, the higher mean wave power density of wave resources does not necessarily correspond to the larger optimal buoy or PTO sizes, but it contributes to the lower LCOE. In addition, the optimal PTO force limit converges at around 0.4 to 0.5 times the maximum required PTO force for the corresponding sea sites. Compared with other methods, this proposed method shows a better potential in sizing and reducing LCOE., Offshore and Dredging Engineering, Transport Engineering and Logistics, Ship Hydromechanics and Structures

In dredging, production estimating is carried out mainly with analytical physical models of the different dredging processes. Slurry transport of settling slurries and cutting processes in sand, clay and rock are already covered in two other books by the author. Other processes like hopper sedimentation and erosion, water jet fluidization, cutter head spillage, pump/pipeline dynamics and clamshell dredging are covered in this Special Topics Edition. New topics may be added in the near future., Creative Commons license CC BY-NC-SA 4.0 https://creativecommons.org/licenses/by-nc-sa/4.0, Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, atmospheric rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. For each case considered, the equations/model for the cutting forces, power and specific energy are given. The models are verified with laboratory research, mainly at the Delft University of Technology, but also with data from literature., Creative Commons license CC BY-NC-SA 4.0 https://creativecommons.org/licenses/by-nc-sa/4.0, Offshore and Dredging Engineering

Slurry transport is a very important means of transporting solids through a pipeline. To improve the efficiency of slurry transport, especially in coarse particle transport, which is subject to problems such as strong resistance and easy blockage, more of the internal structure of the flow must be known. Empirical and analytical models are inadequate for this purpose. Therefore, in this study, a coupling mechanism is established between the computational fluid dynamics (CFD) and discrete element method (DEM). The CFD-DEM coupling was applied and research was conducted on the internal flow structure characteristics of microscopic motion and flow transition for coarse particles in a pipeline. The flow-regime transition processes of coarse 10-mm particles were analyzed qualitatively at velocities of 2 m·s −1 , 5 m·s −1 , 8 m·s −1 and 10 m·s −1 in a 0.1524-m diameter pipe, and quantitative analyses were performed on both the concentration distribution and the pressure gradient of particles in regimes of fixed bed flow, sliding bed flow and heterogeneous flow. Moreover, from the perspective of force analysis of particles, the law of sedimentation movement of particles is discussed, and the reason for the change in concentration distribution is explained. The research presented here provides insight into the internal structure of the flow and gives quantitative indications of pressure gradient and concentration distributions., Offshore and Dredging Engineering

In dredging, production estimating is carried out mainly with analytical physical models of the different dredging processes. Slurry transport of settling slurries and cutting processes in sand, clay and rock are already covered in two other books by the author. Other processes like hopper sedimentation and erosion, water jet fluidization, cutter head spillage, pump/pipeline dynamics and clamshell dredging are covered in this Special Topics Edition. New topics may be added in the near future., TU Delft OPEN Textbook, Offshore and Dredging Engineering

Slurry transport is a very important means of transporting solids through a pipeline. To improve the efficiency of slurry transport, especially in coarse particle transport, which is subject to problems such as strong resistance and easy blockage, more of the internal structure of the flow must be known. Empirical and analytical models are inadequate for this purpose. Therefore, in this study, a coupling mechanism is established between the computational fluid dynamics (CFD) and discrete element method (DEM). The CFD-DEM coupling was applied and research was conducted on the internal flow structure characteristics of microscopic motion and flow transition for coarse particles in a pipeline. The flow-regime transition processes of coarse 10-mm particles were analyzed qualitatively at velocities of 2 m·s −1 , 5 m·s −1 , 8 m·s −1 and 10 m·s −1 in a 0.1524-m diameter pipe, and quantitative analyses were performed on both the concentration distribution and the pressure gradient of particles in regimes of fixed bed flow, sliding bed flow and heterogeneous flow. Moreover, from the perspective of force analysis of particles, the law of sedimentation movement of particles is discussed, and the reason for the change in concentration distribution is explained. The research presented here provides insight into the internal structure of the flow and gives quantitative indications of pressure gradient and concentration distributions., Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, atmospheric rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. For each case considered, the equations/model for the cutting forces, power and specific energy are given. The models are verified with laboratory research, mainly at the Delft University of Technology, but also with data from literature., TU Delft OPEN Textbook, Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated.The book covers horizontal transport of settling slurries (Newtonian slurries). Non-settling (non-Newtonian) slurries are not covered., TU Delft OPEN Textbook, Offshore and Dredging Engineering

In slurry transport there are many models for fine, medium and coarse particles, based on the assumption that the particles are still small compared to the pipe diameter. However, when the particle size is not small compared to the pipe diameter (up to 25% of the pipe diameter) the models do not give a good prediction of the hydraulic gradient. The existing models assume suspended flow at high line speeds, but the question is, will there still be suspension in this case. Yagi, Vlasak, Ravelet and others carried out experiments with very large particles and describe the phenomena occurring, but do not give a physical or mathematical model for this case. At low line speeds the physics of the slurry transport can be described with the 2LM or 3LM models (Wilson, Doron, etc.), but at high line speeds these models are not sufficient. Will there be (pseudo) homogeneous transport at high line speeds or will there still be a sort of sliding bed (sliding flow)? How does the sliding friction coefficient behave? How does the slip velocity behave? Is there still a Limit Deposit Velocity? To answer these questions the available experimental data from literature is investigated. This paper shows a collection of experimental data from literature of different authors, shows the general trends and a model for very coarse particles at high line speeds. © BHR Group Hydrotransport 20., Offshore and Dredging Engineering

Most methods for determining the hydraulic gradient of slurry transport are based on a single particle size. A few methods describe how to deal with a graded Particle Size Distribution (PSD). The way these methods deal with graded PSD's is very different. The original Durand/Condolios method defines an equivalent particle diameter, based on a weighted average of particle Froude numbers using the parallel resistor method. The heterogeneous Wilson model uses a power for the dependency of the hydraulic gradient on the line speed, where this power is smaller, the more graded the PSD. This power has a maximum of 1.7 for single sized particle solids and a minimum of 0.25 in the Wilson model. The Sellgren & Wilson 4 component model divides the PSD in 4 components based on particle size boundaries. For each particle size based component, the corresponding model is applied. These models are the homogeneous model for very small particles influencing the viscosity, the reduced Equivalent Liquid Model for small particles, the heterogeneous model for medium sized particles and the two-layer and three layer models for large particles. The 4th model considered is the Delft Head Loss & Limit Deposit Velocity Framework, dividing the PSD in fractions. The number of fractions is free to choose, but normally 9 is sufficient. First the carrier liquid properties are adjusted based on the fines fraction. Secondly the hydraulic gradient curve is determined for each fraction. These hydraulic gradient curves are added, multiplied with the fraction. The paper describes the 4 methods and gives pros and cons of each method. The 4 methods are compared with each other. © BHR Group Hydrotransport 20., Voor overeenkomstige PowerPoint-presentatie zie: https://www.researchgate.net/profile/Sape_Miedema/publication/317684169_Paper_12_Miedema/data/5948c4b3458515db1fd71cb3/Paper-12-Miedema.pdf, Offshore and Dredging Engineering

Most concentration distribution models are based on the advection diffusion equation for two-dimensional (2D) channel flow. These models may or may not incorporate hindered settling based on the cross-sectional averaged spatial volumetric concentration. These models also use a diffusivity based on the turbulent momentum diffusivity, sometimes corrected for the particle diameter (Kaushal & Tomita (2000)). The result is a 2D concentration profile. To make this applicable for pipe flow, the integrated concentration profile must match the cross-sectional averaged spatial volumetric concentration, which requires a correction. Still the result is based on a constant hindered settling velocity, which is not correct considering the concentration over the vertical coordinate is not a constant. An iterative method has been developed to correct the concentration profile for the local hindered settling velocity. About 4 iterations are necessary to find the resulting concentration profile., Offshore and Dredging Engineering

In slurry transport there are many models for fine, medium and coarse particles, based on the assumption that the particles are still small compared to the pipe diameter. However, when the particle size is not small compared to the pipe diameter (up to 25% of the pipe diameter) the models do not give a good prediction of the hydraulic gradient. The existing models assume suspended flow at high line speeds, but the question is, will there still be suspension in this case. Yagi, Vlasak, Ravelet and others carried out experiments with very large particles and describe the phenomena occurring, but do not give a physical or mathematical model for this case. At low line speeds the physics of the slurry transport can be described with the 2LM or 3LM models (Wilson, Doron, etc.), but at high line speeds these models are not sufficient. Will there be (pseudo) homogeneous transport at high line speeds or will there still be a sort of sliding bed (sliding flow)? How does the sliding friction coefficient behave? How does the slip velocity behave? Is there still a Limit Deposit Velocity? To answer these questions the available experimental data from literature is investigated. This paper shows a collection of experimental data from literature of different authors, shows the general trends and a model for very coarse particles at high line speeds. © BHR Group Hydrotransport 20., Offshore and Dredging Engineering

Most methods for determining the hydraulic gradient of slurry transport are based on a single particle size. A few methods describe how to deal with a graded Particle Size Distribution (PSD). The way these methods deal with graded PSD's is very different. The original Durand/Condolios method defines an equivalent particle diameter, based on a weighted average of particle Froude numbers using the parallel resistor method. The heterogeneous Wilson model uses a power for the dependency of the hydraulic gradient on the line speed, where this power is smaller, the more graded the PSD. This power has a maximum of 1.7 for single sized particle solids and a minimum of 0.25 in the Wilson model. The Sellgren & Wilson 4 component model divides the PSD in 4 components based on particle size boundaries. For each particle size based component, the corresponding model is applied. These models are the homogeneous model for very small particles influencing the viscosity, the reduced Equivalent Liquid Model for small particles, the heterogeneous model for medium sized particles and the two-layer and three layer models for large particles. The 4th model considered is the Delft Head Loss & Limit Deposit Velocity Framework, dividing the PSD in fractions. The number of fractions is free to choose, but normally 9 is sufficient. First the carrier liquid properties are adjusted based on the fines fraction. Secondly the hydraulic gradient curve is determined for each fraction. These hydraulic gradient curves are added, multiplied with the fraction. The paper describes the 4 methods and gives pros and cons of each method. The 4 methods are compared with each other. © BHR Group Hydrotransport 20., Voor overeenkomstige PowerPoint-presentatie zie: https://www.researchgate.net/profile/Sape_Miedema/publication/317684169_Paper_12_Miedema/data/5948c4b3458515db1fd71cb3/Paper-12-Miedema.pdf, Offshore and Dredging Engineering

Most concentration distribution models are based on the advection diffusion equation for two-dimensional (2D) channel flow. These models may or may not incorporate hindered settling based on the cross-sectional averaged spatial volumetric concentration. These models also use a diffusivity based on the turbulent momentum diffusivity, sometimes corrected for the particle diameter (Kaushal & Tomita (2000)). The result is a 2D concentration profile. To make this applicable for pipe flow, the integrated concentration profile must match the cross-sectional averaged spatial volumetric concentration, which requires a correction. Still the result is based on a constant hindered settling velocity, which is not correct considering the concentration over the vertical coordinate is not a constant. An iterative method has been developed to correct the concentration profile for the local hindered settling velocity. About 4 iterations are necessary to find the resulting concentration profile., Offshore and Dredging Engineering

Different approaches are present in literature for slurry transport in inclined pipes. Most models assume that the socalled solids effect, the hydraulic gradient of the mixture minus the hydraulic gradient of the carrier liquid, has to be multiplied by the cosine of the inclination angle to a certain power. These powers vary from 0.25 to 1.7. In addition, a potential energy term is added. The models are usually based on the heterogeneous flow regime and do not take different flow regimes into account. A homogeneous component is absent in the models, resulting in a zero solids effect in a vertical pipe. In this paper an overview is given of the existing models, with the pro’s and con’s. In this paper, also a more fundamental model is derived for each flow regime separately. The advantage of this is also that shifts of the transition of the flow regimes become visible. The cosine and sine of the inclination angle still plays an important role, but more complicated than just a power. The new derived model is compared with data from literature., Offshore and Dredging Engineering

Models for modeling slurry flow present difficulties on long lines with large pipe diameters and with broad graded sands or gravels. In order to get more insight into the slurry flow process, the Delft Head Loss & Limit Deposit Velocity Framework has been developed that integrates the 5 main flow regimes of slurry transport: fixed or stationary bed transport, sliding bed transport, heterogeneous transport, homogeneous transport and sliding flow transport. Additional models for; the limit deposit velocity, the holdup function, the bed height, the concentration distribution and graded sands and gravels, complement the Framework. The Framework is based on constant spatial volumetric concentration curves for uniform sands and gravels. The models for the flow regimes and the limit deposit velocity are based on energy considerations. At line speeds near the transition of the heterogeneous and homogeneous flow regimes however, there is no sharp transition between the two flow regimes for medium sized particles. The limits of medium sized particles depend on the solid and liquid properties and on the pipe diameter. It is often observed that the hydraulic gradient lies in between the Equivalent Liquid Model (ELM) and the pure liquid Darcy Weisbach model at higher line speeds, resulting in the conclusion that at higher line speeds the pure liquid hydraulic gradient is approached. Based on energy considerations however, it is shown that the heterogeneous hydraulic gradient collapses due to turbulent near wall lift neutralizing the particle submerged weight and collisions with the pipe wall, while at higher line speeds the turbulent eddies integrate particles, resulting in a hydraulic gradient approaching a reduced ELM (RELM). For medium sized particles in large diameter pipes there is a gap between the moment the heterogeneous hydraulic gradient collapses and the homogeneous hydraulic gradient builds up, resulting in a hydraulic gradient approaching the RELM hydraulic grad, Accepted Author Manuscript, Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. After the soil has been excavated it is usually transported hydraulically as a slurry over a short (TSHD’s) or a long distance (CSD’s). Estimating the pressure losses and determining whether or not a bed will occur in the pipeline is of great importance. Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior. Although some basic knowledge about the subject is required and expected, dimensionless numbers, the terminal settling velocity (including hindered settling), the initiation of motion of particles, erosion and the flow of a liquid through a pipe are summarized. An overview is given of experiments and theories found in literature. The results of experiments are considered to be the physical reality. Semi empirical theories based on these experiments are considered to be an attempt to describe the physical reality in a mathematical way. These semi empirical theories in general match the experiments on which they are based, but are also limited to the range of the different parameters as used for these experiments. Some theories have a more fundamental character and may be more generic as long as the starting points on which they are based apply. Observing the results of many experiments gives the reader the possibility to form his/her own impression of the processes involved in slurry transport. Flow regimes are identified and theoretical models are developed for each main flow regime based on constant volumetric spatial concentration. The 5 main flow regimes are the fixed or stationary bed regime, the sliding bed regime, the heterogeneous regime, the homogeneous regime and the sliding flow regime. A new model for the, Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. After the soil has been excavated it is usually transported hydraulically as a slurry over a short (TSHD’s) or a long distance (CSD’s). Estimating the pressure losses and determining whether or not a bed will occur in the pipeline is of great importance. Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior. Although some basic knowledge about the subject is required and expected, dimensionless numbers, the terminal settling velocity (including hindered settling), the initiation of motion of particles, erosion and the flow of a liquid through a pipe are summarized. An overview is given of experiments and theories found in literature. The results of experiments are considered to be the physical reality. Semi empirical theories based on these experiments are considered to be an attempt to describe the physical reality in a mathematical way. These semi empirical theories in general match the experiments on which they are based, but are also limited to the range of the different parameters as used for these experiments. Some theories have a more fundamental character and may be more generic as long as the starting points on which they are based apply. Observing the results of many experiments gives the reader the possibility to form his/her own impression of the processes involved in slurry transport. Flow regimes are identified and theoretical models are developed for each main flow regime based on constant volumetric spatial concentration. The 5 main flow regimes are the fixed or stationary bed regime, the sliding bed regime, the heterogeneous regime, the homogeneous regime and the sliding flow regime. A new model for the, Offshore and Dredging Engineering

Models for modeling slurry flow present difficulties on long lines with large pipe diameters and with broad graded sands or gravels. In order to get more insight into the slurry flow process, the Delft Head Loss & Limit Deposit Velocity Framework has been developed that integrates the 5 main flow regimes of slurry transport: fixed or stationary bed transport, sliding bed transport, heterogeneous transport, homogeneous transport and sliding flow transport. Additional models for; the limit deposit velocity, the holdup function, the bed height, the concentration distribution and graded sands and gravels, complement the Framework. The Framework is based on constant spatial volumetric concentration curves for uniform sands and gravels. The models for the flow regimes and the limit deposit velocity are based on energy considerations. At line speeds near the transition of the heterogeneous and homogeneous flow regimes however, there is no sharp transition between the two flow regimes for medium sized particles. The limits of medium sized particles depend on the solid and liquid properties and on the pipe diameter. It is often observed that the hydraulic gradient lies in between the Equivalent Liquid Model (ELM) and the pure liquid Darcy Weisbach model at higher line speeds, resulting in the conclusion that at higher line speeds the pure liquid hydraulic gradient is approached. Based on energy considerations however, it is shown that the heterogeneous hydraulic gradient collapses due to turbulent near wall lift neutralizing the particle submerged weight and collisions with the pipe wall, while at higher line speeds the turbulent eddies integrate particles, resulting in a hydraulic gradient approaching a reduced ELM (RELM). For medium sized particles in large diameter pipes there is a gap between the moment the heterogeneous hydraulic gradient collapses and the homogeneous hydraulic gradient builds up, resulting in a hydraulic gradient approaching the RELM hydraulic grad, Accepted Author Manuscript, Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. The productions (and thus the dimensions) of the excavating equipment range from mm3/sec - cm3/sec to m3/sec. In oil drilling layers with a thickness of a magnitude of 0.2 mm are cut, while in dredging this can be of a magnitude of 0.1 m with cutter suction dredges and meters for clamshells and backhoe’s. Some equipment is designed for dry soil, while others operate under water saturated conditions. Installed cutting powers may range up to 10 MW. For both the design, the operation and production estimation of the excavating equipment it is important to be able to predict the cutting forces and powers. After the soil has been excavated it is usually transported hydraulically as a slurry over a short (TSHD’s) or a long distance (CSD’s) or mechanically. Estimating the pressure losses and determining whether or not a bed will occur in the pipeline is of great importance. Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In TSHD’s the soil has to settle during the loading process, where also sedimentation and erosion will be in equilibrium. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior. This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, atmospheric rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. The failure mechanism of sand, dry and water saturated, is the so called Shear Type. The failure mechanism of clay is the so called Flow Type, but under certain circumstances also the Curling Type and the Tear Type are po, Dr.ir. Sape A. Miedema (November 8th 1955) obtained his M.Sc. degree in Mechanical Engineering with honours at the Delft University of Technology (DUT) in 1983. He obtained his Ph.D. degree on research into the basics of soil cutting in relation with ship motions, in 1987. From 1987 to 1992 he was Assistant Professor at the chair of Dredging Technology. In 1992 and 1993 he was a member of the management board of Mechanical Engineering & Marine Technology of the DUT. In 1992 he became Associate Professor at the DUT with the chair of Dredging Technology. From 1996 to 2001 he was appointed Head of Studies of Mechanical Engineering and Marine Technology at the DUT, but still remaining Associate Professor of Dredging Engineering. In 2005 he was appointed Head of Studies of the MSc program of Offshore & Dredging Engineering and he is also still Associate Professor of Dredging Engineering. In 2013 he was also appointed as Head of Studies of the MSc program Marine Technology of the DUT. Dr.ir. S.A. Miedema teaches (or has taught) courses on soil mechanics and soil cutting, pumps and slurry transport, hopper sedimentation and erosion, mechatronics, applied thermodynamics related to energy, drive system design principles, mooring systems, hydromechanics and mathematics. He is (or has been) also teaching at Hohai University, Changzhou, China, at Cantho University, Cantho Vietnam, at Petrovietnam University, Baria, Vietnam and different dredging companies in the Netherlands and the USA. His research focuses on the mathematical modeling of dredging systems like, cutter suction dredges, hopper dredges, clamshell dredges, backhoe dredges and trenchers. The fundamental part of the research focuses on the cutting processes of sand, clay and rock, sedimentation processes in Trailing Suction Hopper Dredges and the associated erosion processes. Lately the research focuses on hyperbaric rock cutting in relation with deep sea mining and on hydraulic transport of solids/liquid settling sl, Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. The productions (and thus the dimensions) of the excavating equipment range from mm3/sec - cm3/sec to m3/sec. In oil drilling layers with a thickness of a magnitude of 0.2 mm are cut, while in dredging this can be of a magnitude of 0.1 m with cutter suction dredges and meters for clamshells and backhoe’s. Some equipment is designed for dry soil, while others operate under water saturated conditions. Installed cutting powers may range up to 10 MW. For both the design, the operation and production estimation of the excavating equipment it is important to be able to predict the cutting forces and powers. After the soil has been excavated it is usually transported hydraulically as a slurry over a short (TSHD’s) or a long distance (CSD’s) or mechanically. Estimating the pressure losses and determining whether or not a bed will occur in the pipeline is of great importance. Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In TSHD’s the soil has to settle during the loading process, where also sedimentation and erosion will be in equilibrium. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior. The lecture notes are complemented with the book The Delft Sand, Clay & Rock Cutting Model, by Dr.ir. Sape A. Miedema and available at www.iospress.nl. Additional information can be found on www.delftdredging.com, www.dredgingengineering.com, www.dhlldv.com and www.dscrcm.com., Offshore and Dredging Engineering

In slurry transport of settling slurries in Newtonian fluids, it is often stated that one should apply a line speed above a critical velocity, because blow this critical velocity there is the danger of plugging the line. There are many definitions and names for this critical velocity. It is referred to as the velocity where a bed starts sliding or the velocity above which there is no stationary bed or sliding bed. Others use the velocity where the hydraulic gradient is at a minimum, because of the minimum energy consumption. Most models from literature are one term one equation models, based on the idea that the critical velocity can be explained that way. Here the following definition is used: The critical velocity is the line speed below which there may be either a stationary bed or a sliding bed, depending on the particle diameter and the pipe diameter, but above which no bed (stationary or sliding) exists, the Limit Deposit Velocity (LDV). The way of determining the LDV depends on the particle size, where 5 regions are distinguished. These regions for sand and gravel are roughly; very small particles up to 0.014–0.040 mm (d < ?v), small particles from ?v–0.2 mm, medium particles in a transition region from 0.2–2.00 mm, large particles > 2 mm and very large particles > 0.015·Dp. The lower limit of the LDV is the transition between a sliding bed and heterogeneous transport. The new model is partly based on physics and correlates well with experiments from literature., Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. The productions (and thus the dimensions) of the excavating equipment range from mm3/sec - cm3/sec to m3/sec. In oil drilling layers with a thickness of a magnitude of 0.2 mm are cut, while in dredging this can be of a magnitude of 0.1 m with cutter suction dredges and meters for clamshells and backhoe’s. Some equipment is designed for dry soil, while others operate under water saturated conditions. Installed cutting powers may range up to 10 MW. For both the design, the operation and production estimation of the excavating equipment it is important to be able to predict the cutting forces and powers. After the soil has been excavated it is usually transported hydraulically as a slurry over a short (TSHD’s) or a long distance (CSD’s) or mechanically. Estimating the pressure losses and determining whether or not a bed will occur in the pipeline is of great importance. Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In TSHD’s the soil has to settle during the loading process, where also sedimentation and erosion will be in equilibrium. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior. This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, atmospheric rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. The failure mechanism of sand, dry and water saturated, is the so called Shear Type. The failure mechanism of clay is the so called Flow Type, but under certain circumstances also the Curling Type and the Tear Type are po, Dr.ir. Sape A. Miedema (November 8th 1955) obtained his M.Sc. degree in Mechanical Engineering with honours at the Delft University of Technology (DUT) in 1983. He obtained his Ph.D. degree on research into the basics of soil cutting in relation with ship motions, in 1987. From 1987 to 1992 he was Assistant Professor at the chair of Dredging Technology. In 1992 and 1993 he was a member of the management board of Mechanical Engineering & Marine Technology of the DUT. In 1992 he became Associate Professor at the DUT with the chair of Dredging Technology. From 1996 to 2001 he was appointed Head of Studies of Mechanical Engineering and Marine Technology at the DUT, but still remaining Associate Professor of Dredging Engineering. In 2005 he was appointed Head of Studies of the MSc program of Offshore & Dredging Engineering and he is also still Associate Professor of Dredging Engineering. In 2013 he was also appointed as Head of Studies of the MSc program Marine Technology of the DUT. Dr.ir. S.A. Miedema teaches (or has taught) courses on soil mechanics and soil cutting, pumps and slurry transport, hopper sedimentation and erosion, mechatronics, applied thermodynamics related to energy, drive system design principles, mooring systems, hydromechanics and mathematics. He is (or has been) also teaching at Hohai University, Changzhou, China, at Cantho University, Cantho Vietnam, at Petrovietnam University, Baria, Vietnam and different dredging companies in the Netherlands and the USA. His research focuses on the mathematical modeling of dredging systems like, cutter suction dredges, hopper dredges, clamshell dredges, backhoe dredges and trenchers. The fundamental part of the research focuses on the cutting processes of sand, clay and rock, sedimentation processes in Trailing Suction Hopper Dredges and the associated erosion processes. Lately the research focuses on hyperbaric rock cutting in relation with deep sea mining and on hydraulic transport of solids/liquid settling sl, Offshore and Dredging Engineering

In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. The productions (and thus the dimensions) of the excavating equipment range from mm3/sec - cm3/sec to m3/sec. In oil drilling layers with a thickness of a magnitude of 0.2 mm are cut, while in dredging this can be of a magnitude of 0.1 m with cutter suction dredges and meters for clamshells and backhoe’s. Some equipment is designed for dry soil, while others operate under water saturated conditions. Installed cutting powers may range up to 10 MW. For both the design, the operation and production estimation of the excavating equipment it is important to be able to predict the cutting forces and powers. After the soil has been excavated it is usually transported hydraulically as a slurry over a short (TSHD’s) or a long distance (CSD’s) or mechanically. Estimating the pressure losses and determining whether or not a bed will occur in the pipeline is of great importance. Fundamental processes of sedimentation, initiation of motion and erosion of the soil particles determine the transport process and the flow regimes. In TSHD’s the soil has to settle during the loading process, where also sedimentation and erosion will be in equilibrium. In all cases we have to deal with soil and high density soil water mixtures and its fundamental behavior. The lecture notes are complemented with the book The Delft Sand, Clay & Rock Cutting Model, by Dr.ir. Sape A. Miedema and available at www.iospress.nl. Additional information can be found on www.delftdredging.com, www.dredgingengineering.com, www.dhlldv.com and www.dscrcm.com., Offshore and Dredging Engineering

In slurry transport of settling slurries in Newtonian fluids, it is often stated that one should apply a line speed above a critical velocity, because blow this critical velocity there is the danger of plugging the line. There are many definitions and names for this critical velocity. It is referred to as the velocity where a bed starts sliding or the velocity above which there is no stationary bed or sliding bed. Others use the velocity where the hydraulic gradient is at a minimum, because of the minimum energy consumption. Most models from literature are one term one equation models, based on the idea that the critical velocity can be explained that way. Here the following definition is used: The critical velocity is the line speed below which there may be either a stationary bed or a sliding bed, depending on the particle diameter and the pipe diameter, but above which no bed (stationary or sliding) exists, the Limit Deposit Velocity (LDV). The way of determining the LDV depends on the particle size, where 5 regions are distinguished. These regions for sand and gravel are roughly; very small particles up to 0.014–0.040 mm (d < ?v), small particles from ?v–0.2 mm, medium particles in a transition region from 0.2–2.00 mm, large particles > 2 mm and very large particles > 0.015·Dp. The lower limit of the LDV is the transition between a sliding bed and heterogeneous transport. The new model is partly based on physics and correlates well with experiments from literature., Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

The increase of world population has been requiring more and more lands for human activities, which is why the world dredging market has been significantly growing up during the past 20 years. In dredging engineering, underwater excavation process is one of the major procedures which involves complicated physics, no matter it is sand, clay or rock on the seabed. It is important to reasonably estimate the cutting force needed on the excavator blade, which will help to improve the design and reduce the wear of the equipment so that higher working efficiency can be achieved. However, it is known that the cutting force is greatly influenced by the local water pressure especially in deep water. The fluid flow will change the pore pressure distribution and meanwhile apply certain force to the solid particles. Since the experiments to measure the cutting force are expensive, a numerical model is then needed to describe the physics in it. In this paper, the author tends to use the discrete element modeling to describe the solid particle movement and particle-particle interactions, and the finite volume method to calculate the fluid pressure distribution and flow velocity. Besides, a coupling deck is used between the two models to exchange the information to describe the fluid-solid interaction. This research has proven the feasibility of applying such a method in the underwater excavation process. Further calibration and validation are still necessary depends on the soil properties of the seabed., Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

Sand, clay and rock have to be excavated for a variety of purposes, such as dredging, trenching, mining (including deep sea mining), drilling, tunnel boring and many other applications. Many excavations take place on dry land, but they are also frequently required in completely saturated conditions, and the methods necessary to accomplish them consequently vary widely. This book provides an overview of cutting theories. It begins with a generic model, valid for all types of soil (sand, clay and rock), and continues with the specifics of dry sand, water-saturated sand, clay, atmospheric rock and hyperbaric rock. Small blade angles and large blade angles are discussed for each soil type, and for each case considered the equations/model for cutting forces, power and specific energy are given. With models verified by laboratory research, principally from the Delft University of Technology, and data from other recognized sources, this book will prove an invaluable reference for anybody whose work involves major excavations of any kind., Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

Sand, clay and rock have to be excavated for a variety of purposes, such as dredging, trenching, mining (including deep sea mining), drilling, tunnel boring and many other applications. Many excavations take place on dry land, but they are also frequently required in completely saturated conditions, and the methods necessary to accomplish them consequently vary widely. This book provides an overview of cutting theories. It begins with a generic model, valid for all types of soil (sand, clay and rock), and continues with the specifics of dry sand, water-saturated sand, clay, atmospheric rock and hyperbaric rock. Small blade angles and large blade angles are discussed for each soil type, and for each case considered the equations/model for cutting forces, power and specific energy are given. With models verified by laboratory research, principally from the Delft University of Technology, and data from other recognized sources, this book will prove an invaluable reference for anybody whose work involves major excavations of any kind., Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. The failure mechanism of sand, dry and water saturated, is the so called Shear Type. The failure mechanism of clay is the so called Flow Type, but under certain circumstances also the Curling Type and the Tear Type are possible. Rock will usually fail in a brittle way. This can be brittle tensile failure, the Tear Type, for small blade angles, but it can also be brittle shear failure, which is of the Shear Type of failure mechanism for larger blade angles. Under hyperbaric conditions rock may also fail in a more ductile way according to the Flow Type of failure mechanism. For each case considered, the equations/model for the cutting forces, power and specific energy are given. The models are verified with laboratory research, mainly at the Delft University of Technology, but also with data from literature., Marine & Transport Technology, Mechanical, Maritime and Materials Engineering

This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. The failure mechanism of sand, dry and water saturated, is the so called Shear Type. The failure mechanism of clay is the so called Flow Type, but under certain circumstances also the Curling Type and the Tear Type are possible. Rock will usually fail in a brittle way. This can be brittle tensile failure, the Tear Type, for small blade angles, but it can also be brittle shear failure, which is of the Shear Type of failure mechanism for larger blade angles. Under hyperbaric conditions rock may also fail in a more ductile way according to the Flow Type of failure mechanism. For each case considered, the equations/model for the cutting forces, power and specific energy are given. The models are verified with laboratory research, mainly at the Delft University of Technology, but also with data from literature., Marine & Transport Technology, Mechanical, Maritime and Materials Engineering

Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

Marine and Transport Technology, Mechanical, Maritime and Materials Engineering

Mechanical Maritime and Materials Engineering

Mechanical Maritime and Materials Engineering