Academic literature on the topic 'Hydromechanical Efficiency'
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Journal articles on the topic "Hydromechanical Efficiency"
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Sharipov, V. M., Yu S. Shchetinin, S. V. Gaev, and O. V. Troshkin. "Energy analysis of dual-flow hydromechanical gears." Traktory i sel hozmashiny 84, no. 10 (October 15, 2017): 39–49. http://dx.doi.org/10.17816/0321-4443-66342.
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Two-flow hydromechanical transmissions are becoming increasingly common in the construction of modern land transport and traction machines (tractors, automobile and high-speed crawler vehicles). This is mainly due to the desire to increase the efficiency of transmission. In order to select a dual-flow hydromechanical transmission scheme in relation to specific operating conditions, it is necessary to know the advantages and disadvantages of various schemes, their potential capabilities. The evaluation of the operation of each circuit can be made on the basis of their kinematic, power, and energy analysis. The results of the kinematic and force analysis of two-flow hydromechanical gears were previously developed by the authors of this article. In energy analysis, the following estimated parameters were used to compare the performance of the transmission: г|ГМП - efficiency of transmission; РМ - power factor in the mechanical branch of the transmission; РН - power factor on the pump wheel of the torque converter; РТ - the power factor on the turbine wheel of the torque converter. The paper considers 12 schemes of two-flow hydrome-chanical gears with a differential link at the input and output with mixed gear coupling, the results of their energy analysis are given. For each of the schemes considered, analytical dependencies of the estimated parameters on the internal parameters of the hydromechanical transmission were obtained, which were used as the characteristic k of the planetary gear set, the power transfer ratio йгт of the torque converter, and the kinematic gear ratio игмп of the hydromechanical transmission. The results of calculations performed on a computer using the external characteristic of a specific torque converter are obtained and presented in graphical form. The obtained results can be used in developing recommendations for the choice of a two-flow hydromechanical transmission scheme.
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Sharipov, V. M., Yu S. Shchetinin, S. V. Gaev, and O. V. Troshkin. "POWER ANALYSIS OF DUAL-FLOW HYDROMECHANICAL GEARS." Traktory i sel hozmashiny 84, no. 2 (February 15, 2017): 35–41. http://dx.doi.org/10.17816/0321-4443-66273.
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Dual-flow hydromechanical transmissions are becoming increasingly widespread in the designs of modern land transport and traction machines (tractors, automobiles and high-speed crawler vehicles). This happens mainly due to the desire to increase the efficiency of transmission, although the capabilities of dual-flow hydromechanical transmissions are broader. In order to select a dual-flow hydromechanical transmission scheme in relation to specific operating conditions, it is necessary to know the advantages and disadvantages of various schemes, their potential capabilities. The evaluation of the operation of each circuit can be made on the basis of their kinematic and force analysis. The article deals with 12 dual-flow schemes of hydromechanical transmission with a differential element in inlet and outlet with a mixed meshing of gears, the results of the power analysis are shown. For the estimated parameters of a double-flow hydromechanical transmission were taken: й - power ratio of a double- гмп flow hydromechanical transmission; ан - coefficient of loading of the pump wheel of the torque converter; ам -load factor of the mechanical branch of the closed transmission contour; аa - load factor of the solar gear of the three-link differential mechanism. For each of the schemes considered, analytical dependencies of the estimated parameters on the internal parameters of the hydromechanical transmission were obtained. For the parameters were used the characteristic k of planetary gear set, power йгт and kinematic игт gear ratios of torque converter. It is assumed that, at the boundaries of the range й = да and й = 0. Calculations have been performed to determine the parameters й , гмп гмп гмп ан , ам u аа for different values of k and й , results of which made possible to evaluate the potential transforming properties of the schemes of two-flow hydromechanical transmissions independently of the model of the used hydrotransformer.
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Yang, Shujun, Yong Bao, Xianzhi Tang, Xiaojuan Jiao, Deqing Yang, and Qing Wang. "Integrated Control of Hydromechanical Variable Transmissions." Mathematical Problems in Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/290659.
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A hydromechanical variable transmission (HMT) has advantages of continuous variation and high efficiency. So it is one of the ideal transmissions of heavy vehicles. The continuous speed varying process involves speed governing in range and range shift. Integrated control strategy of the HMT is proposed in this paper. The algorithm of the asymmetric saturated incremental proportional integral derivative (PID) speed control strategy in range and range shift conditions are derived. And this paper presents the range shift logic and range shift control strategies. A controller model is built in Matlab Simulink and cosimulated with the model of vehicle equipped with a two-range HMT. The HMT prototype hardware-in-the-loop simulation (HILS) platform of the integrated control strategy is built. The HILS results show that the range shift process is smooth and speed fluctuation does not happen. In the throttle stable stage, the engine speed is adjusted to the near optimal speed, and its change rules are in accordance with simulation results. The integrated control strategy is reasonable.
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Sharipov, V. M., G. O. Kotiev, Yu S. Shchetinin, M. V. Vyaznikov, S. V. Gaev, and M. G. Rozenoer. "On the selection of parameters of double-flow hydromechanical transmission for industrial and forestry tractors." Traktory i sel hozmashiny 83, no. 3 (March 15, 2016): 8–14. http://dx.doi.org/10.17816/0321-4443-66117.
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Double-flow hydromechanical transmissions are widely used in industrial and forestry tractors. The main advantage of such transmission is the higher value of the maximum efficiency coefficient in comparison with the single-flow one. The article presents a method of selection of parameters of such transmissions for industrial and forestry tractors. In this case, it considers the hydromechanical transmission with a differential unit at the input and at the output. Three-link differential devices with mixed type of gear engagement are used as the differential unit. All of the twelve possible schemes of double-flow hydrodynamical transmissions are considered. It is shown that double-flow hydrodynamical transmission has an operation mode when the torque converter turbine is rotating counter to the rotation of pump wheel. This factor is taken into account during the selection of parameters of double-flow hydrodynamical transmission. The article describes the method of construction of external characteristic of the transmission and matching of its load characteristic with the full-load curve of diesel engine. The matching is performed by three ways: the selection of required value of active diameter of torque converter; the selection of reduction ratio of matching gear; the selection of characteristic of planetary gear set. It is found that for the most common scheme of double-flow hydromechanical transmission when the characteristic of planetary gear set is reduced, its maximum efficiency coefficient is increased, the active diameter of torque converter is reduced and the relative rotation frequency of satellite gears of three-link differential device is increased. In this case, the rotation frequency of satellite gears limits the minimum value of characteristic of planetary gear set. Increasing of characteristic of planetary gear set leads to the reducing of transparency of the hydromechanical transmission and to increasing of its transformation ratio. It is shown that the double-flow hydromechanical transmission allows to utilize more fully the converting properties of engine in comparison with the single-flow one; it allows to change the torque value if external engine load is changing, that is very important for industrial and forestry tractors.
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Vyaznikov, M. V., S. V. Gaev, V. M. Sharipov, Yu S. Shchetinin, and M. Yu Esenovskiy-Lashkov. "PLOTTING OF EXTERNAL CHARACTERISTIC OF A TORQUE CONVERTER WITH COUNTER-ROTATING MODE OF TURBINE WHEEL IN DOUBLE-FLOW HYDROMECHANICAL TRANSMISSION OF AN INDUSTRIAL TRACTOR." Traktory i sel hozmashiny 84, no. 4 (April 15, 2017): 11–15. http://dx.doi.org/10.17816/0321-4443-66260.
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Double-flow hydromechanical transmissions are widely used in industrial tractors and high-speed tracked vehicles. The main advantage of this transmission is a higher value of the maximum efficiency compared to a single-flow hy-dromechanical transmission. Considered is the double-flow hydromechanical transmission of the industrial tractor D8L «Caterpillar» and the results of its bench experimental studies are presented. In this transmission, the torque converter operates in a certain rotational speed range of the driven shaft in the counter-rotating mode of the turbine wheel. In the domestic and foreign literature there are no external characteristics of torque converters with the mode of turbine wheel anti-rotation. It was not possible to obtain such external characteristics of the torque converter experimentally so far. This is due to the complexity of providing a test-bench with anti-rotation mode of the turbine wheel of the torque converter. This mode is realized only in a double-flow hydromechanical transmission. However, with its experimental test-bench studies, existing techniques did not allow plotting of an external characteristic of the for the turbine wheel counter-rotating mode. At experimental test-bench researches of a torque converter only it is also impossible to provide the mode of counter rotation of a turbine wheel. In this paper, a method is given for plotting of external characteristic of a torque converter with turbine wheel anti-rotation mode, if an external characteristic of a double-flow hydromechanical transmission is known. The validity and reliability of the proposed approach to the plotting of the external characteristic of the torque converter with turbine wheel counter rotation mode is confirmed by the results of bench experimental studies of the double-flow hydromechanical transmission and the torque converter of the industrial tractor D8L Caterpillar.
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Wang, Junyan, Changgao Xia, Xin Fan, and Junyu Cai. "Research on Transmission Characteristics of Hydromechanical Continuously Variable Transmission of Tractor." Mathematical Problems in Engineering 2020 (August 12, 2020): 1–14. http://dx.doi.org/10.1155/2020/6978329.
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This paper proposes a new transmission scheme of hydromechanical continuously variable transmission (HMCVT) for tractors. The HMCVT has 4 working ranges in each of the front and rear directions. The speed characteristic and the torque characteristic of HMCVT are theoretically derived. On the basis of HMCVT power flow direction, the Крейнeс formula is used to calculate the transmission efficiency. Then, the image analysis method is used to study the influence of parameters on the transmission efficiency of HMCVT, and the main influencing factors are found. The results of theoretical derivation demonstrate that, by coordinating control of the HST displacement ratio and the engagement conditions of shifting clutches, the stepless speed regulation of HMCVT at the tractor speed of 0–50 km/h can be realized. The proposed HMCVT has the ability to continuously transmit and change torque over all working ranges. The overall transmission efficiency of HMCVT is at a high level. To verify the theoretical derivation, Amesim simulation software is used for the modeling and simulation of HMCVT. The simulation results are consistent with the theoretical analysis results. Therefore, the HMCVT proposed in this paper has the advantages of compact structure and high transmission efficiency, and it is suitable for matching tractors.
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Kotiyev, G. O., V. V. Vasilyev, and A. V. Gorbatovskiy. "Estimation of use efficiency of automatic transmission of «torque converter - coupling - gearbox» type." Traktory i sel hozmashiny 83, no. 2 (February 15, 2016): 16–20. http://dx.doi.org/10.17816/0321-4443-66138.
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The paper describes a mathematical model for wheeled vehicle with automatic transmission of «torque converter - coupling - gearbox» type. In order to compare this type of transmission and mechanical one with same number of gears and ratios, optimal characteristics of torque converter for considered vehicle are selected. The paper presents the results of simulation of wheeled vehicle moving for both variants of gearbox in conditions involving variable resistance and moving velocity assigned by driver. Efficiency of hydromechanical transmission use is estimated.
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Zhang, Guangqing, Hengtong Zhang, Yanyan Ge, Wei Qiu, Maohua Xiao, Xiaomei Xu, and Minghui Zhou. "Mechanical Efficiency of HMCVT under Steady-State Conditions." Shock and Vibration 2021 (September 3, 2021): 1–14. http://dx.doi.org/10.1155/2021/4275922.
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Hydromechanical continuously variable transmission (HMCVT) technology has been widely used due to its advantages of ride comfort and fuel economy. The relatively uniform efficiency expression of HMCVT is obtained by studying torque and transmission ratios to reveal steady-state characteristics and predict the output torque. Mathematical models of torque ratios are derived by analyzing the HMCVT system power flow and calculating the equivalent meshing power of epicyclic gear train and efficiency for the hydraulic system. The relationship between mechanical system transmission and hydraulic system parameters is established using the torque ratios, and a mechanical system demanding surface is proposed. Two numerical examples of the HMCVT system with single and dual variable units are demonstrated to establish an effective and convenient method. The method is validated through a physical prototype TA1-02 test.
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Rybak, A. T., A. V. Ivanovskaya, P. P. Batura, and A. Yu Pelipenko. "Synchronization in multi-motor hydromechanical systems." Advanced Engineering Research 21, no. 4 (January 10, 2022): 337–45. http://dx.doi.org/10.23947/2687-1653-2021-21-4-337-345.
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Introduction. The paper submits the analysis of existing design solutions of flow dividers used to synchronize hydraulic drives of working bodies of technological and mobile machines. The market demands for multithreaded throttle flow dividers without valves with the controlled division ratio, such as multi-axle vehicle chassis, are identified. The objective of the work was to analyze the possibility and rationale for developing a throttle four-way flow divider without valves with sensing elements of the Venturi tube type. The solution should provide the synchronicity of movement (rotation) of more than three working bodies of technological and mobile machines.Materials and Methods. A patent search for the designs of hydraulic flow dividers is carried out, and systems that require the division of the hydraulic fluid flow into more than two executive bodies are considered. An upgrade option, which allows dividing the flow into four branches, is proposed for the design of a three-channel throttle flow divider without valves.Results. The urgency of developing a multithreaded throttle flow divider without valves for application in industrial and mobile machines is validated. Two types of four-flow dividers are considered, their weaknesses are indicated. It is noted that the development of a multithreaded throttle flow divider based on the designs created in 1989 and 1991 will reduce the number of hydraulic pumps and get rid of the series connection of double-flow dividers. In this way, it is possible to reduce pressure losses in the hydraulic system and implement adaptive control of hydraulic motors of multi-motor mobile machines. The possibility to obtain a divider/combiner into four flows by adding an outlet chamber connected to the membrane chamber through a channel entering the Venturi nozzle on the basis of a three-flow throttle divider is shown. The principle of operation of such equipment is described.Discussion and Conclusions. The principles of construction of throttle flow dividers without valves are considered. An upgrade option is proposed to increase the number of division channels from three to four. However, to validate the operability of this design, a numerical analysis of the various modes of operation of the divider is required — calculation of the reduced volumetric stiffness of its working cavities. The information obtained can be used to modernize the hydraulic units of technological and mobile machines, increase their reliability, manufacturability, and efficiency. The issues that need to be solved in further research are identified.
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Zenfira Huseynli, Kamran Fatalizade, Zenfira Huseynli, Kamran Fatalizade. "STUDY OF THE EFFICIENCY OF HYDROMECHANICAL PACKERS USED IN THE OPERATION OF DELICATED WELLS." ETM - Equipment, Technologies, Materials 11, no. 03 (May 23, 2022): 45–51. http://dx.doi.org/10.36962/etm11032022-45.
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The article considers the general shortcomings of packers designed for carrying out geological and technical measures in an open hole. These packer deficiencies can cause problems in the operation of wells, which leads to an increase in non-productive time or even to the loss of a well and, as a result, leads to high costs for oil and gas companies. The design of sliding support elements, centering the structure in the open hole, preventing leakage of the sealing rubber element due to the occurrence of a pressure drop, and subsequently ensuring a reliable packer break, has been studied. Key words: hydromechanical packer, wellbore, sealing element, the packer unit.
Dissertations / Theses on the topic "Hydromechanical Efficiency"
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Larsson, Viktor, and L. Viktor Larsson. "Simulation and Testing of Energy Efficient Hydromechanical Drivlines for Construction Equipment." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-107495.
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Increased oil prices and environmental issues have increased a need of loweringthe emissions from and the fuel consumption in heavy construction machines. Anatural solution to these issues is a lowered input power through downsizing ofthe engine. This implies a demand on higher transmission efficiency, in order tominimize the intrusion on vehicle performance. More specifically, alternatives tothe conventional torque converter found in heavier applications today, must beinvestigated. One important part of this is the task of controlling the transmissionwithout jeopardising the advantages associated with the torque converter, such asrobustness and controllability.In this thesis, an alternative transmission concept for a backhoe loader is investigated.The studied concept is referred to as a 2-mode Jarchow power-splittransmission, where a mechanical path is added to a hydrostatic transmission inorder to increase transmission efficiency. The concept is evaluated in computerbased simulations as well as in hardware-in-the-loop simulations, where a physicalhydrostatic transmission is exposed for the loads caused by the vehicle duringvarying conditions. The loads are in turn simulated according to developed modelsof the mechanical parts of the vehicle drive line.In total, the investigated concept can be used instead of the torque converterconcept, if the hydrostatic transmission is properly controlled. The results alsoshow that there is a high possibility that the combustion engine in the backhoeloader can be downsized from 64 kW to 55 kW, which would further increase thefuel savings and reduce the emissions.
Book chapters on the topic "Hydromechanical Efficiency"
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Deby, Fabrice, Myriam Carcasses, and Alain Sellier. "The Probabilistic Method: An Efficient Tool to Take into Account the Parameters Variability of Modeling for Durability Design Process." In Thermo-Hydromechanical and Chemical Coupling in Geomaterials and Applications, 391–98. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118623565.ch39.
Full textConference papers on the topic "Hydromechanical Efficiency"
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Saihood, Tariq, and Rebello Samuel. "Mud Loss Prediction in Realtime Through Hydromechanical Efficiency." In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211777-ms.
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Abstract Improving drilling efficiency is more of a concern as we prepare for fully autonomous drilling. It is evident that increasing the rate of penetration for minimum cost is not always the best solution, as the drilling problems encountered may negate the benefits. One of the significant drilling problems to be considered is mud loss. This study presents a method to evaluate and quantify circulation loss with a specific energy concept. The methodology is used to compare different wells with and without mud loss conditions using real-time data from two wells. Mechanical specific energy and hydraulic mechanical specific energy (HMSE) using the pressure component were calculated. The unconfined compressive strength pressure, UCS, is also calculated from log data to calculate drilling efficiency. The Realtime loss circulation depths are pointed as the digit [1] for no loss circulation event and digit [0] for loss circulation event. An equation is suggested to relate the loss circulation event to the amount of energy applied to the loss zones. For the present study, several cases with Realtime data were analyzed. The drillability is calculated and modified to account for the differential pressure effect on the ROP. The drilling efficiency, defined by using UCS to HMSE, is modified to reflect the differential pressure effect showed the mud loss conditions in the wells where the mud loss was observed. Also, the impact of the differential pressure between the bottom hole pressure and the formation pressure is presented in this study. The results show a big difference between the amount of energy applied in the loss formation and the required energy to excavate the formation in the analyzed wells. The calculated loss circulation severity was fingerprinted to estimate the amount of mud loss from daily drilling reports. The method developed also predicted the severity of loss circulation using the HMSE and UCS. The effect of the differential pressure can be estimated in real-time and quantified between the high-pressure depth interval and the low-pressure zones. The proposed workflow was tested on historical wells; the results are compared against the proposed analytical model. The results were also verified with the daily drilling reports from the field to confirm the predictions of the algorithm presented. The results predicted were synchronous. A new modified approach of using pressure in the mechanical specific energy is conducted. The study suggests monitoring the ratio of the ROP over the modified drilling efficiency. The drilling crew now has the whole picture about all contributed drilling parameters to manage the drilling parameters to improve the drilling efficiency.
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Milani, Massimo, Luca Montorsi, Stefano Terzi, Gelmini Mario, Fabrizio Panizzolo, and Giovanni Profumo. "Fuel Consumption Reduction of Off-Road Vehicles by Improving the Efficiency of the Hydromechanical Variable Transmission’s Lubrication and Actuation Systems." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23822.
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Abstract The paper investigates the efficiency of a hydro-mechanical variable transmission combining experimental and numerical approaches in order to develop operating strategies for power transmission losses reduction due to hydraulic circuits design. Two operating regions, characterized by high working time, have been detected analyzing the telescopic boom handler load spectral map of a real off-road vehicle transmission; the first one characterized by high output speed and the second one by low speed and torque transmission. The efficiency of the former region has been increased by improving the fluid dynamic behavior of the lubrication system, which is greatly affected by the high flow rate generated by the fixed displacement pump operating at high speed, while the latter has been improved regulating the flow pressure of the actuation system with a controlled relief valve. The power losses of the system are experimentally determined testing an instrumented transmission on an ad-hoc test rig. CFD dynamic models are adopted for the lubrication circuit optimization, addressing its real geometrical features as well as the actual operating conditions. Furthermore, the influence of the hydrodynamic resistance of the reverse and first wet clutches on the transmission power losses is investigated regulating the lubrication flow through an on/off valve. Tests demonstrated that up to 6.5 kW can be saved at high transmission ratios. Finally, the effect of the two regulating strategies have been estimated in terms of energy saving and C02 emission reduction on the total vehicle life. Results proved that 5600 kWh and 7250 kWh saved energy can be achieved for the two strategies corresponding to 3.7 tons and 4.6 tons of avoided CO2 respectively.
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Käppi, Timo J. "Semiempirical Model for Variable Displacement Pump With Load Sensing Regulator and Power Restrictor." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/fpst-25023.
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Abstract In this paper modeling of variable displacement pump system is discussed. The system described is typically used in mobile hydraulic applications. An easy-to-parameterize loss model is presented which is based on the Dorey’s model. The model identification is done semi-empirically with a reduced number of parameters. Two parameters are required to identify the volumetric losses and four to determine the hydromechanical efficiency. The accuracy of the loss model is proven by comparing calculated values between the measured values of a commercial axial piston pump. The relative error in total efficiency is less than 4% over the whole range of variables and thus acceptable. The pump system model presented includes the operation of load sensing regulator and power restrictor. The pump system model also includes the dynamic effect of a load sensing line from the mobile valve to the pump regulator and the first order dynamics of the pump itself. The suggested model is usable in carrying out the system level simulation of mobile hydraulic machine systems. Simple examples demonstrate the application.
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Rannow, Michael B., Haink C. Tu, Perry Y. Li, and Thomas R. Chase. "Software Enabled Variable Displacement Pumps: Experimental Studies." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14973.
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The majority of hydraulic systems are controlled using a metering valve or the use of variable displacement pumps. Metering valve control is compact and has a high control bandwidth, but it is energy inefficient due to throttling losses. Variable displacement pumps are far more efficient as the pump only produces the required flow, but comes with the cost of additional bulk, sluggish response, and added cost. In a previous paper [1], a hydromechanical analog of an electronic switch-mode power supply was proposed to create the functional equivalent of a variable displacement pump. This approach combines a fixed displacement pump with a pulse-width-modulated (PWM) on/off valve, a check valve, and an accumulator. The effective pump displacement can be varied by adjusting the PWM duty ratio. Since on/off valves exhibit low loss when fully open or fully closed, the proposed system is potentially more energy efficient than metering valve control, while achieving this efficiency without many of the shortcomings of traditional variable displacement pumps. The system also allows for a host of programmable features that can be implemented via control of the PWM duty ratio. This paper presents initial experimental validation of the concept as well as an investigation of the system efficiency. The experimental apparatus was built using available off-the-shelf components and uses a linear proportional spindle valve as the PWM valve. Experimental results confirm that the proposed approach can achieve variable control function more efficiently than a valve controlled system, and that by increasing the PWM frequency and adding closed-loop control can decrease system response times and of the output ripple magnitude. Sources of inefficiency and their contributions are also investigated via modeling, simulation and are validated by experiments. These indicate design parameters for improving inefficiency.
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Barannyk, Oleksandr, Brad Buckham, and Peter Oshkai. "Effect of Chordwise Flexibility and Depth of Submergence on an Oscillating Plate Underwater Propulsion System." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30148.
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This work was dedicated to the experimental study of oscillating plate propulsors undergoing a combination of heave translation and pitch rotation. The oscillation kinematics are inspired by swimming mechanisms employed by fish and other marine animals. The primary focus was on the propulsive characteristics of such oscillating plates, which were studied by means of direct force measurements in the thrust-producing regime. Experiments were performed at constant Reynolds number and constant heave amplitude. By varying the Strouhal number, the depth of submergence and the chordwise flexibility of the plate, it was possible to investigate corresponding changes in the generated thrust and the hydromechanical efficiency. It was possible to establish a set of parameters, including the driving frequency of the system, the ratio of rigid to flexible segment length of the plate, and the range of Strouhal numbers that led to a peak efficiency of approximately 80%. The experiments involving plates with various ratios of rigid to flexible segment lengths showed that greater flexibility increased the propulsive efficiency and thrust compared to an identical motion of the purely rigid plate. By submerging the plate at different depths, it was observed that the proximity of the propulsor to the bottom of the channel led to overall increase in the thrust coefficient.
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Bellio, Philip R. "Digital Controls and Modern Fuel Systems for Marine Prime Movers." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0324.
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Digital controls and modern fuel systems for marine prime movers are beginning to populate the waterways and oceans, but long after industrial facilities recognized their benefits and standardized on them. Additionally, it is somewhat ironic that many marine prime movers, particularly aeroderivative gas turbines, still utilize aircraft or aircraft-derivative hydromechanical controls, yet require significant engine room manning. Digital controls, electrically actuated fuel and air valves, shipboard networks, and CRT-based operator interfaces have all been proven, and are available for every marine prime mover application. It appears to be more of a mindset than anything else preventing the move to electronic controls and modern fuel systems. Additional roadblocks to change may be “comfort with the old stuff”, marine certifications, and high availability of older hardware. As demands for improved efficiency, decreased emissions, and reduced operating expense continue there will be more pressure to upgrade existing older controls and fuel systems, as well as build ships with prime movers equipped with current control technology. A modern electronic control designed for prime movers which interfaces to not only the prime mover, can also provide data to shipboard systems, as well as be configured for satellite links to off-shore facilities. Other advantages of a digital control and modern fuel system include: • Software configurable/dependent • Self-diagnostics and monitoring • Condition-based maintenance • Elimination of hydraulics • Reduced manning requirements • Precise air and fuel metering • Current technology
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McClure, Mark W., Mohsen Babazadeh, Sogo Shiozawa, and Jian Huang. "Fully Coupled Hydromechanical Simulation of Hydraulic Fracturing in Three-Dimensional Discrete Fracture Networks." In SPE Hydraulic Fracturing Technology Conference. SPE, 2015. http://dx.doi.org/10.2118/spe-173354-ms.
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Abstract We developed a hydraulic fracturing simulator that implicitly couples fluid flow with the stresses induced by fracture deformation in large, complex, three-dimensional discrete fracture networks. The simulator can describe propagation of hydraulic fractures and opening and shear stimulation of natural fractures. Fracture elements can open or slide, depending on their stress state, fluid pressure, and mechanical properties. Fracture sliding occurs in the direction of maximum resolved shear stress. Nonlinear empirical relations are used to relate normal stress, fracture opening, and fracture sliding to fracture aperture and transmissivity. Fluid leakoff is treated with a semianalytical one-dimensional leakoff model that accounts for changing pressure in the fracture over time. Fracture propagation is treated with linear elastic fracture mechanics. Non-Darcy pressure drop in the fractures due to high flow rate is simulated using Forchheimer's equation. A crossing criterion is implemented that predicts whether propagating hydraulic fractures will cross natural fractures or terminate against them, depending on orientation and stress anisotropy. Height containment of propagating hydraulic fractures between bedding layers can be modeled with a vertically heterogeneous stress field or by explicitly imposing hydraulic fracture height containment as a model assumption. The code is efficient enough to perform field-scale simulations of hydraulic fracturing with a discrete fracture network containing thousands of fractures, using only a single compute node. Limitations of the model are that all fractures must be vertical, the mechanical calculations assume a linearly elastic and homogeneous medium, proppant transport is not included, and the locations of potentially forming hydraulic fractures must be specified in advance. Simulations were performed of a single propagating hydraulic fracture with and without leakoff to validate the code against classical analytical solutions. Field-scale simulations were performed of hydraulic fracturing in a densely naturally fractured formation. The simulations demonstrate how interaction with natural fractures in the formation can help explain the high net pressures, relatively short fracture lengths, and broad regions of microseismicity that are often observed in the field during stimulation in low permeability formations, and which are not predicted by classical hydraulic fracturing models. Depending on input parameters, our simulations predicted a variety of stimulation behaviors, from long hydraulic fractures with minimal leakoff into surrounding fractures to broad regions of dense fracturing with a branching network of many natural and newly formed fractures.
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Finnigan, T. "Simulation of a Biomimetic Tidal Current Energy Conversion Device." In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92498.
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Aquatic species have evolved highly efficient modes of swimming through natural selection. The most efficient in terms of forward thrust are Thunniform-mode swimming species (eg. tuna, shark). These species are propelled by lateral oscillation of a stiff lunate caudal fin with motion primarily limited to the fin and peduncle (aft tail) regions. In this paper we describe the application of biomimicry to the use of swimming hydromechanics in the development of a new tidal current energy conversion device. The development process is briefly described and some preliminary simulation results, based on computational fluid dynamics, are presented. Results indicate that potential exists for the development of low-cost efficient devices based on the biomimetic concept.
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Wegner, Stephan, Stefan Gels, Dal Sik Jang, and Hubertus Murrenhoff. "Experimental Investigation of the Cylinder Block Movement in an Axial Piston Machine." In ASME/BATH 2015 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fpmc2015-9529.
Full textAbstract:
The greatest share of hydromechanic and volumetric losses in axial piston machines are produced within the tribological interfaces piston / cylinder, cylinder block / valve plate and slipper / swash plate. Hydrostatic and hydrodynamic effects are used to minimise the sum of solid friction, viscous friction and throttle losses. Other tribological interfaces have minor influence on efficiency losses in most operating points in machines of this type. This paper focuses on experimental investigations with the objective to acquire further knowledge on the cylinder block / valve plate contact. The investigations are part of a project funded by the German Research Foundation in which experimental and simulative investigations are combined to identify the effects influencing this tribological interface. The experiments focus on the multi-directional movement of the cylinder block and the friction torque within the contact. Therefore a test rig was built, capable of measuring the cylinder block movement in all degrees of freedom and the friction torque between both parts. A sensor system is built around a standard rotary group of an axial piston pump with a spherical cylinder block / valve plate contact. The pump functionality is maintained and measurements under standard operating conditions up to 30 MPa are possible. Procedures of the design process and descriptions of the measuring system are presented, followed by results of the cylinder block movement measurement, comparing the behavior under different pressure levels and speeds.
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Harris, Carl. "Use of Side Beaches in the 200 m Towing Tank at the Institute for Marine Dynamics." In SNAME 22nd American Towing Tank Conference. SNAME, 1989. http://dx.doi.org/10.5957/attc-1989-028.
Full textAbstract:
The Clear Water Towing Tank (CWTT) at the Institute for Marine Dynamics (IMD) measures 200 m long x 12 m wide x 7 m deep with a usable run length of approximately 150 meters. The tank is equipped with an electrically driven (manned) towing carriage capable of speeds up to 10 mis and a hydraulically operated, computer controlled dual-flap wavemaker which can generate regular waves of up to 1.0 min height or irregular waves with significant wave heights of up to 0,3 meters. The tank when built was not equipped with any form of side beaches. Retro-fitting the facility with traditional-style side beaches would be a major expense. Adjustable-height vertical baffles would also, perhaps, be impractical given the limited amount of space between the underside of the towing carriage and the water surface. In an effort to improve the efficiency of use of this facility, it was decided to experiment with low cost flexible side beaches in the CWTT. Beaches of this type are described by Enzinger and Johnson (Reference 1). The authors report a marked decrease in tank settling time and a corresponding increase in the testing efficiency of their tanks. One notable difference in the IMD approach is the use of these 'beaches' on both sides of the tank rather than just one as is the case in the Hydromechanics Laboratory of the U.S. Naval Academy. It was logical to assume that having energy absorbing devices on both walls would decrease the settling time even further for a nominal extra expense. This paper describes the use of the (double) 'course rope' beaches in the CWTT and experiments conducted in calm water and regular waves to determine their effectiveness for this facility.