Presently, there is a four-year window to prepare engines for upcoming TIER V regulations through solutions for peak power shaving and downsizing of diesel engines. In particular, Non-road mobile machinery(NRMM) offer a promising and challenging field of application due to their duty cycles, which includes high and short power peaks and extreme working conditions. In this paper, a series hybrid electric powertrain for a mining loader is presented with the goal of reducing the fuel consumption. A full-scale mining loader powertrain prototype was built to exploit the benefits of a series hybrid electric powertrain at low traction requirements with a combination of decentralized e.g. zonal hydraulics. Corespondingly, this paper introduces the structure of the mining loader and initial mathematical model of the system of a Direct Driven hydraulics (DDH). In this research, an experimental test was conducted, and the initial results are presented in this paper.

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Thesis (M. Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 115-120).

The purpose of this thesis has been to compare and analyse the use of digital hydraulic actuators in place of traditional actuators in aircraft control surface manipulation. Digital hydraulic actuator referring to a hydraulic actuator where the power has been discretized using discrete on/off-valves. For this purpose three simulation models have been used. The first model consists of a benchmark model, designed to represent a digital hydraulic actuator acting on a mass under the influence of an external spring load. The discretization in this case comes from the fact that three separate pressure levels have been used to power a four-chambered tandem piston, resulting in 81 possible force combinations.The second simulation model represents a 6 degrees of freedom aircraft model parametrised to behave like a F16 fighter aircraft. The purpose of this model has been to serve as a means to implement the digital actuator in an aircraft. The third model has been heavily based on the F16 model but re-parametrised such that it represents a delta canard aircraft. The actuators in the aircraft models was initially mounted on the control surface primarily dedicated for the manoeuvre which was simulated, in this case a step in altitude, meaning that the control surface was the elevon.As it would turn out the digital actuator had trouble achieving the precision required in order to adequately fly the aircraft at a low enough energy consumption. As such the idea took form to implement a hybrid design where the digital actuator would be paired with a proportional actuator on a separate control surface, flaperons. The digital actuator would then only require to be positioned in a close enough position and once there lock in place, leaving the proportional actuator to handle the fine tuning and trim of the aircraft. It would appear that by using the hybrid actuator design the energy consumption during the right circumstances could be reduced by as much as 40% for the delta canard configuration and 30% for the F16 case.

In recent years, magnitudes of flood estimates used in hydraulic design have increased for many reservoirs. Consequently, many existing spillways are now deficient as they do not meet current discharge capacity requirements. To rehabilitate existing, fixed-width spillways, labyrinth weirs are often viable solutions. For reservoir applications, arcing labyrinth weirs into the reservoir increases hydraulic efficiency. This results from better cycle orientation to the approaching flow field. This study supplements available arced labyrinth weir hydraulic data by observing flow characteristics of three laboratory-scale physical models and two numerical (CFD) models. Physical model results provide head (energy)-discharge data and empirical coefficients for hydraulic design. Results also show that increasing the arc angle improves efficiency at H/P<0.3, where H/P is upstream piezometric head divided by weir height; after which, efficiency improvements diminish as downstream submergence also increases. The purpose of the CFD analysis was to assess the appropriateness of CFD as a design tool for arced labyrinth weir head-discharge relationship development. The CFD model results found good agreement with the physical model data indicating CFD’s usefulness as a hydraulic design tool; however, it is recommended that CFD models be calibrated to reliable laboratory or field data. This study’s data may be used, with sound engineering judgement, to aid in hydraulic design of arced labyrinth weirs

Presently, there is a four-year window to prepare engines for upcoming TIER V regulations through solutions for peak power shaving and downsizing of diesel engines. In particular, Non-road mobile machinery(NRMM) offer a promising and challenging field of application due to their duty cycles, which includes high and short power peaks and extreme working conditions. In this paper, a series hybrid electric powertrain for a mining loader is presented with the goal of reducing the fuel consumption. A full-scale mining loader powertrain prototype was built to exploit the benefits of a series hybrid electric powertrain at low traction requirements with a combination of decentralized e.g. zonal hydraulics. Corespondingly, this paper introduces the structure of the mining loader and initial mathematical model of the system of a Direct Driven hydraulics (DDH). In this research, an experimental test was conducted, and the initial results are presented in this paper.

River training structures are widely used to create and maintain navigable waterways, to restore rivers and channels in a more stable condition, to promote environmental benefits, and to protect people and infrastructure from damages or floods. Few historical datasets on the changes and impacts in secondary waterbodies resulting from notched river training structures are available for the Lower Mississippi River. Access to the notched training structures on the Lower Mississippi River remains difficult and inhibits data collection for monitoring efforts. This increases the need for alternative methods such as numerical models for assessing the performance of the notched training structures. A quasi-three-dimensional Adaptive Hydraulics model was assembled and used to provide a hydraulic assessment of seven notched river training structures in the Lower Mississippi River. The hydraulic assessment of the notches included assessing the impacts to navigation, the long-term trends, and the potential for aquatic wildlife habitat diversity.

Noise in a fluid system can be treated with a prototypical liner-style suppressor, an expansion chamber which includes an internal annulus of syntactic foam. A syntactic foam liner consists of host material with hollow microspheres which collapse under pressure to add compliance to the suppressor. The liner effectively increases the transmission loss of the suppressor, or ratio between inlet and outlet acoustic energy. Currently, liner-style suppressors are not commercially available. This study investigates the integration of solid liner material within suppressor shells while also analyzing the effect of flow-smoothing diffusors on the transmission loss of the suppressor. The diffusors function to center the liner within the device, while reducing the potential for turbulence-induced self-noise. The diffusor may also impact the longevity of the liner, by reducing mechanical erosion. The results of the study provide additional insight to the commercial viability of the liner-style suppressor.

During the past three years the Institute for Fluid Power Drives and Controls in Aachen has developed a new hydraulic system for mobile machinery called STEAM. The system represents a new step in excavator hydraulics, as it aims to reduce both the hydraulic system losses as well as those of the internal combustion engine by using a hybrid hydraulic architecture with accumulators. Starting with initial simulation studies the development has been followed by scaled test bench measurements and has progressed to a full scale validation using an 18 t excavator. The following publication aims to summarise the results obtained thus far with the aim of making them available to industry and encouraging their implementation in future applications.

Liebherr mobile harbor cranes use electrical generators to provide electrical power for load attachment devices such as container spreaders or magnets. Upcoming exhaust and noise emission standards and energy saving considerations lead to a broad diesel engine speed range. The challenging design aspect is to ensure a constant speed of the asynchronous generator by the hydraulic drive system. In addition, electrical load profiles of inductive consumers usually have DT1 system characteristics with very small time constants. They evoke fast torque variations interfacing the hydraulic transmission. Liebherr mobile harbor cranes, see Figure 1, usually have a closed hydraulic circuit containing a hydraulic pump with a high displacement volume that is adjusted electronically in accordance to the current diesel engine speed. Regarding the energy saving aspects, a further minimization of the diesel engine speed leads to a larger pump size with increasing torque losses. Depending on the pressure setting, the volume flows can be reduced in constant pressure grids. Especially in part-load operation this results in better efficiency compared to closed hydraulic circuits by minimizing the displacement volume of hydraulic components. To obtain a stable generator speed, it is essential to adjust the displacement volume of the hydraulic unit for equalizing its input torque with the Figure 1: LHM 800 Group 10 - Mobile Hydraulics | Paper 10-5 199 generator load torque. In interaction with the software-based control architecture, the stability of the electrical frequency depends on the mass inertia of the generator drive and time constants of the embedded hydraulic actuators. The system model, represented by ODEs is established and verified with a hydraulic simulation software. On that basis, the design approach of a PI-state-controller is presented. Corresponding controller gains and state feedback parameters are determined by pole placement techniques. To conclude this investigation a comparison between the hydraulically closed circuit and the constant pressure grid is shown by simulation and measurement data.