The problem of pressure ripple propagation in fluid filled pipelines has been understood for a long time. To-date, however, mathematical representations of pressure ripple standing waves generated in hydraulic systems have been limited to very simple systems operating at low mean pressure levels and over limited frequency ranges. This report details the evaluation and development of the mathematical impedance representation of hydraulic systems and system components. With the result that these can be used to predict, with confidence, pressure ripple levels in hydraulic circuits under normal conditions of operation and over a wide frequency range. The confidence comes from the detailed practical examination of the pressure ripple levels created in hydraulic systems, made up from standard hydraulic components, operated under normal conditions of pressure and flow. Although the test circuits used are only representative of practical systems, they do not perform any specific function, they incorporate all the major features of circuit design, including branch lines and impedances (components) in series. Lastly, the ability to model with accuracy the pressure ripple levels within a hydraulic circuit provides the means by which they can become part of the overall design specification for a hydraulic system. This thesis illustrates the difficulties which restrict the practical implementation of this ideal.

An investigation has been made of the effectiveness of reinforced flexible hoses in decreasing pressure fluctuations in a hydraulic circuit. An understanding has been obtained of the properties and length of hose required to achieve a quieter system. The existing theory of longitudinal wave propagation in hoses has been extended by considering the effect of fluid viscosity and by making an accurate allowance for the inner lining. The theory has been checked by comparing the wave properties obtained from resonance tests with those calculated from the physical properties of hose and fluid by using the theory. A method of calculating pressure fluctuations in a complete hydraulic system consisting of one or more lengths of hose has been developed. In many cases, motion of the ends of hoses can be neglected which simplifies the calculations. The results for simple circuits have been compared with those obtained experimentally. A theoretical investigation has been made of the effects of the physical properties of a hose on the wave properties. It has been found helpful to split up wall stiffness into two components corresponding to actual or effective extension of the reinforcing cords and to changes in cord angle. There are two ways in which hoses can be used to reduce the pressure fluctuations in a system. A short tuned length of hose can be used to reduce pressure fluctuation at a particular frequency, or a longer length can be used for broadband attenuation. Both approaches have been investigated theoretically and experimentally, although only the latter is of general practical applicability. High attenuation is achieved with extensible cords and with high loss factors associated with wall deformation. For this reason nylon reinforced hoses are effective. The theory also enables the normal surface velocity of a hose, and hence the sound power radiated from it, to be calculated.

A thorough study of standing waves in hydraulic lines is carried out using transmission line theory. Special emphasis is attached to the representation of standing wave patterns of different systems by three dimensional graphs. From this study a new experimental test method has been developed for evaluating the fluid borne noise characteristics of pumps and other hydraulic components. The validity and accuracy of this test method, named the "tuned length method", was assessed by comparison with other existing methods. Unlike many other experimental methods, the tuned length method is capable of testing hydraulic components at low mean pressures. The "tuned length method" was used to evaluate the inlet fluid borne noise characteristics of three gear pumps and an axial piston pump. A purpose built pressurized reservoir was used to control pump inlet conditions. Large pressure fluctuations were measured at some positions in pressurized suction lines and were found to be similar to fluctuations measured in pump discharge lines. The levels of pressure ripple in a pump suction line were found to have a significant affect on the air borne levels generated by the hydraulic system. There is strong evidence of air release occurring in the pump inlet passageway under normal operating conditions. This accounts for the very low pressure ripples in the suction line of a normally aspirated pump. However, this does not affect the volumetric efficiency of the pump. When the pump inlet is pressurized air release is inhibited and the pressure ripple can be very large. An axial piston pump was tested when boosted by another piston pump and the inlet characteristics were evaluated. These characteristics are very similar to those obtained when the pump is supplied by a pressurized reservoir. In order to maintain low fluid borne noise in pump suction lines the mean inlet pressure must be kept as low as possible. The existence of air disolved in the fluid in small quantities is favourable as it prevents very low instantaneous pressures and hence limit the possibility of cavitation. The use of a pressurized reservoir is reccommended for this purpose, as long as steps are taken to avoid solution of additional quantities of air.

This thesis describes the design, development and testing of a distributed parameter hydraulic system simulation program based on the method of characteristics, and is intended to extend and complement the work being carried out at Bath University on the computer aided design of fluid power systems on small computers. The first part of the thesis is an extensive literature review of distributed parameter techniques and related topics, and represents a stock-taking of current simulation methods and their applicability to fluid power system modelling. The method of characteristics is a numerical technique for analysing wave propagation effects in the time domain. A general program structure was designed whereby various systems could be analysed by subroutines modelling the behaviour of individual hydraulic components linked together by pipe models based on the method of characteristics. General aspects of the program operation were tested by simulating a hydrostatic transmission, good correlation was obtained with analytical results, and with a lumped parameter simulation. More specific problems of component modelling were investigated by simulating a Barmag type, 3 port pressure compensated flow control valve. The program was applied to the analysis of pump generated pressure ripple. Good agreement was obtained with experimental results demonstrating the ability of the method of characteristics, as programmed, to accurately predict high frequency effects in hydraulic systems. The program providing an alternative tool for analysing fluid borne noise, which is especially suitable for situations where transient effects are important. 006. The method of characteristics is not ideal for general hydraulic system simulation and the recommendations for future work include a scheme for incorporating it into the existing lumped parameter simulation language (HGSP) developed at Bath University.

<p> Conducting a 2-D sediment transport modeling study on the Sagavanirktok River has offered great insight to bed sediment movement. During the summer of 2017, sediment excavation of two parallel trenches began in the Sagavanirktok River, in an effort to raise the road elevation of the Dalton Highway to remediate against future floods. To predict the time in which the trenches refill with upstream sediment a 2-D numerical model was used. Three scenarios: (1) a normal cumulative volumetric flow, (2) a max discharge event, and (3) a max cumulative volumetric flow, were coupled with three sediment transport equations: Parker, Wilcock-Crowe and Meyer Peter and M&uuml;ller for a total of 9 simulations. Results indicated that scenario (1) predicted the longest time to fill, ranging from 1&ndash;6 years followed by scenario (2), an even shorter time, and scenario (3) showing sustained high flows have the capability to nearly refill the trenches in one year. Because the nature of this research is predictive, limitations exist as a function of assumptions made and the numerical model. Therefore, caution should be taken in analyzing the results. However, it is important to note that this is the first time estimates have been calculated for an extraction site to be refilled on the Sagavanirktok River. Such a model could be transformed into a tool to project filling of future material sites. Ultimately, this could expedite the permitting process, eliminating the need to move to a new site by returning to a site that has been refilled from upstream sediment.</p><p>

Growing global energy demand has prompted the exploitation of non-conventional resources such as Coal Bed Methane (CBM) and conventional resources such as gas-condensate reservoirs. Exploitation of these resources primarily depends on stimulation by hydraulic fracturing. Traditional hydraulic fracturing practices, however, are in many ways inadequate in addressing difficulties associated with these non-conventional and conventional resources. For example, complex in-situ stress distribution, large material property contrasts and unique production mechanism complicate the implementation of hydraulic fracture treatments in CBM and gas-condensate reservoirs respectively. An integrated approach to optimise hydraulic fracture treatments in reservoirs under complex conditions is developed in this thesis. The optimisation methodology integrates a fracture geometry model which predicts fracture geometry for a given set of treatment parameters, a production model which estimates reservoir productivity after stimulation and an economic model which calculates net present value. A stochastic optimisation algorithm combining features of evolutionary computations is used to search for the optimum design. Numerical techniques such as finite element analysis, iterative semi-analytical methods and evolutionary computation are also used. The following are the major contributions of this thesis: 1. A three-dimensional hydraulic fracture geometry model which accounts for poroelastic effects, in-situ stress and rock material properties, has been developed to provide a more realistic description of the hydraulic fracture geometry. This served as a tool to visualise hydraulic fracture propagation for a given in-situ stress distribution, rock material properties and treatment parameters. Furthermore, by accounting for poroelastic effects, it is possible to identify the causes of exceptionally high treatment pressures. 2. An innovative production model was formulated in this thesis to quantify the well deliverability due to hydraulic fracturing. The production model has been used for a range of production scenarios for CBM and gas-condensate reservoirs such as: multiple wells at arbitrary locations and various well types (stimulated and unstimulated wells). 3. The optimisation methodology presented in this work provides a platform for operators to assess risks and gains associated with different field development scenarios. The added feature of sub-optimal NPV contouring provided flexibility to calibrate the treatment design in real-time. The strength of the optimisation methodology lies in the flexibility to: (1) impose design constraints, (2) optimise multiple variables and (3) simulate multiple objectives.

Abridgement of thesis (doctoral)--Kyoto University, 1977. / "Translation of Doctoral Dissertation in Japanese."

In contrast to traditional stamp shaping techniques, tube hydroforming is a realively new shaping technique. But there are still a lack of engineering parameters, mold designs data bases and technique knowledge in this area. This research conducts various tube hydraulic bulge forming experiments, using hydraulic bulge forming testing machines. The pressure and bulge height for UNS C26800 zinc-copper tubing and AISI 1215 carbon steel tubing are measured. The above data are substituted into a hydraulic pressure bulge mathematic model to derive UNS C26800 zinc-copper and AISI 1215 carbon-steel tubes flow stress parameters of initial yielding stress £m0¡Bcoefficient K value and contingency index n value. Moreover, tensile test of the above materials are conducted to the material¡¦s £m0¡BK and n values. then proceed with a comparison of the two sets of statistics. In bulge tests, UNS C26800 zinc-copper tube annealed with temperatures of 300¢J and 500¢J and the not-yet annealing AISI 1215 carbon-steel tube without annealing are used. Additionally, finite element package software is used to simulate the bulge-height and forming pressure. From the comparisons of experimental and analytic results, the deformation mechanisms of tube during the bulge-shaping discussed.

Hydraulic Fracturing stimulation technology is used to increase the amount of oil and gas produced from low permeability reservoirs. The primary objective of the process is to increase the conductivity of the reservoir by the creation of fractures deep into the formation, changing the flow pattern from radial to linear flow. The dynamic conductivity test was used for this research to evaluate the effect of closure stress, temperature, proppant concentration, and flow back rates on fracture conductivity. The objective of performing a dynamic conductivity test is to be able to mimic actual field conditions by pumping fracturing fluid/proppant slurry fluid into a conductivity cell, and applying closure stress afterwards. In addition, a factorial design was implemented in order to determine the main effect of each of the investigated factors and to minimize the number of experimental runs. Due to the stochastic nature of the dynamic conductivity test, each experiment was repeated several times to evaluate the consistency of the results. Experimental results indicate that the increase in closure stress has a detrimental effect on fracture conductivity. This effect can be attributed to the reduction in fracture width as closure stress was increased. Moreover, the formation of channels at low proppant concentration plays a significant role in determining the final conductivity of a fracture. The presence of these channels created an additional flow path for nitrogen, resulting in a significant increase in the conductivity of the fracture. In addition, experiments performed at high temperatures and stresses exhibited a reduction in fracture conductivity. The formation of a polymer cake due to unbroken gel dried up at high temperatures further impeded the propped conductivity. The effect of nitrogen rate was observed to be inversely proportional to fracture conductivity. The significant reduction in fracture conductivity could possibly be due to the effect of polymer dehydration at higher flow rates and temperatures. However, there is no certainty from experimental results that this conductivity reduction is an effect that occurs in real fractures or whether it is an effect that is only significant in laboratory conditions.

This thesis presents and develops efficient and effective methodologies for optimal hydraulic fracture design and fracture performance evaluation. These methods incorporate algorithms that simultaneously optimize all of the treatment parameters while accounting for required constraints. Damage effects, such as closure stress, gel damage and non-Darcy flow, are also considered in the optimal design and evaluation algorithms. Two user-friendly program modules, which are active server page (ASP) based, were developed to implement the utility of the methodologies. Case analysis was executed to demonstrate the workflow of the two modules. Finally, to validate the results from the two modules, results were compared to those from a 3D simulation program. The main contributions of this work are: An optimal fracture design methodology called unified fracture design (UFD) is presented and damage effects are considered in the optimal design calculation. As a by-product of UFD, a fracture evaluation methodology is proposed to conduct well stimulation performance evaluation. The approach is based on calculating and comparing the actual dimensionless productivity index of fractured wells with the benchmark which has been developed for optimized production. To implement the fracture design and evaluation methods, two web ASP based user interfaces were developed; one is called Frac Design (Screening), and the other is Frac Evaluation. Both modules are built to hold the following features. o Friendly web ASP based user interface o Minimum user input o Proppant type and mesh size selection o Damage effects consideration options o Convenient on-line help.