Commutation Loss in Hydrostatic Pumps and Motors

2021 ◽  
Author(s):  
Robin Mommers ◽  
Peter Achten ◽  
Jasper Achten ◽  
Jeroen Potma
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Simulation Model ◽  
Operating Conditions ◽  
Chamber Pressure ◽  
Working Mechanism ◽  
Working Chamber ◽  
Lumped Parameter ◽  
Long Time ◽  
Pressure Changes

Abstract In mobile hydraulic applications, more efficient machinery generally translates to smaller batteries or less diesel consumption, and smaller cooling solutions. A key part of such systems are hydrostatic pumps and motors. While these devices have been around for a long time, some of the causes of energy loss in pump and motors are still not properly defined. This paper focuses on one of the causes of energy loss in pumps and motors, by identifying the energy loss as a result of the process of commutation. By nature, all hydrostatic pumps and motors have some form of commutation: the transition from the supply port to the discharge port of the machine (and vice versa). During commutation, the connection between the working chamber and the ports is temporarily closed. The chamber pressure changes by compression or decompression that is the result of the rotation of the working mechanism. Ideally, the connection to one of the ports is opened once the chamber pressure equals the port pressure. When the connection is opened too early or too late, energy is lost. This paper describes a method to predict the commutation loss using a lumped parameter simulation model. To verify these predictions, experimental data of a floating cup pump was compared to the calculated values, which show a decent match. Furthermore, the results show that, depending on the operating conditions, up to 50% of all losses in this pump are caused by improper commutation.

Parallel Multi-Cycle LES of an Optical Pent-Roof DISI Engine Under Motored Operating Conditions

2017 ◽  
Author(s):  
Noah Van Dam ◽  
Wei Zeng ◽  
Magnus Sjöberg ◽  
Sibendu Som
Keyword(s):  
Experimental Data ◽  
Direct Injection ◽  
Operating Conditions ◽  
New Strategy ◽  
Long Time ◽  
Order Of Magnitude ◽  
Structure Index ◽  
Number Of Cycles ◽  
The Many ◽  
Direct Injection Spark Ignition

The use of Large-eddy Simulations (LES) has increased due to their ability to resolve the turbulent fluctuations of engine flows and capture the resulting cycle-to-cycle variability. One drawback of LES, however, is the requirement to run multiple engine cycles to obtain the necessary cycle statistics for full validation. The standard method to obtain the cycles by running a single simulation through many engine cycles sequentially can take a long time to complete. Recently, a new strategy has been proposed by our research group to reduce the amount of time necessary to simulate the many engine cycles by running individual engine cycle simulations in parallel. With modern large computing systems this has the potential to reduce the amount of time necessary for a full set of simulated engine cycles to finish by up to an order of magnitude. In this paper, the Parallel Perturbation Methodology (PPM) is used to simulate up to 35 engine cycles of an optically accessible, pent-roof Direct-injection Spark-ignition (DISI) engine at two different motored engine operating conditions, one throttled and one un-throttled. Comparisons are made against corresponding sequential-cycle simulations to verify the similarity of results using either methodology. Mean results from the PPM approach are very similar to sequential-cycle results with less than 0.5% difference in pressure and a magnitude structure index (MSI) of 0.95. Differences in cycle-to-cycle variability (CCV) predictions are larger, but close to the statistical uncertainty in the measurement for the number of cycles simulated. PPM LES results were also compared against experimental data. Mean quantities such as pressure or mean velocities were typically matched to within 5–10%. Pressure CCVs were under-predicted, mostly due to the lack of any perturbations in the pressure boundary conditions between cycles. Velocity CCVs for the simulations had the same average magnitude as experiments, but the experimental data showed greater spatial variation in the root-mean-square (RMS). Conversely, circular standard deviation results showed greater repeatability of the flow directionality and swirl vortex positioning than the simulations.

scholarly journals Output of the dependence of the torque on theangleof rotation of the half couplings of the rope hyperbolic coupling «MAMSAR»

2020 ◽  
pp. 140-145
Author(s):  
М.А. Минасян ◽  
А.М. Минасян ◽  
Л.Х. Ха
Keyword(s):  
Experimental Data ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Correction Coefficient ◽  
Labor Costs ◽  
Temperature Conditions ◽  
Hard Radiation ◽  
Long Time ◽  
Temperature Ranges

Виброизолирующие муфты приводов с упругими канатными элементами являются относительно новым направлением и в литературных источниках малоизвестны [1-14]. Они имеют несколько неоспоримых преимуществ перед другими типами муфт. Их характеристики практически не зависят от температурных режимов эксплуатации (температурные диапазоны эксплуатации – от –200 и вплоть до +370 С); они пожаробезопасны, инертны к агрессивным средам; это практически единственный тип муфт, способный долго работать в зонах повышенной и жесткой радиации. Такая нечувствительность к агрессивным средам и условиям эксплуатации позволяет до минимума сократить трудозатраты на их техническое обслуживание. Статья является логическим продолжением работ авторов о возможности использования канатных опор «MAMSAR» [1-4] в качестве отдельных или сборных муфт приводов. В данной работе в качестве объекта исследования рассматривается муфта с гиперболическим канатным элементом [1]. Целью настоящей статьи является вывод зависимости крутящего момента от смещения для муфт приводов с упругими канатными элементами в виде гиперболы «MAMSAR» [1]. Поставленная цель достигается реализацией следующих задач: 1.Получить формулу зависимости крутящего момента от смещения для гиперболической канатной муфты. 2. Экспериментально определить зависимость крутящего момента от смещения для гиперболической канатной муфты 3. Уточнить формулу – зависимость крутящего момента от смещения для гиперболической канатной муфты с использованием коэффициента поправки на основе экспериментальных данных. Vibration-isolating drive couplings with elastic rope elements are a relatively new direction and are little known in the literature [1-14]. They have several undeniable advantages over other types of couplings. Their characteristics practically do not depend on operating temperature conditions (operating temperature ranges – from -200 and up to +370 C); they are fire-safe, inert to aggressive environments; this is almost the only type of couplings that can work for a long time in areas of high and hard radiation. This insensitivity to aggressive environments and operating conditions allows you to minimize the labor costs for their maintenance. The article is a logical continuation of the authors work on the possibility of using "MAMSAR" rope supports [1-4] as separate or combined drive couplings. In this paper, a coupling with a hyperbolic rope element is considered as an object of research [1]. The purpose of this article is to derive the dependence of torque on displacement for drive couplings with elastic rope elements in the form of a "MAMSAR" hyperbola [1]. This goal is achieved by implementing the following tasks: 1. Get the formula for the dependence of torque on displacement for a hyperbolic cable coupling. 2. Experimentally determine the dependence of torque on displacement for a hyperbolic cable coupling 3. Refine the formula-the dependence of torque on displacement for a hyperbolic cable coupling using the correction coefficient based on experimental data.

Accurate Prediction of Axial Piston Machine’s Performance Through a Thermo-Elasto-Hydrodynamic Simulation Model

2013 ◽  
Author(s):  
A. Schenk ◽  
M. Zecchi ◽  
M. Ivantysynova
Keyword(s):  
Simulation Model ◽  
Chamber Pressure ◽  
Computer Simulation Model ◽  
Outlet Port ◽  
Lumped Parameter ◽  
Steady State Temperature ◽  
Sliding Interfaces ◽  
Fluid Film Thickness ◽  
The Impact ◽  
Axial Piston

A new coupled multi-domain computer simulation model able of predicting axial piston hydraulic pump or motor performance is presented in this paper. The model is composed of different modules, each addressing different problems associated with the machine’s operation. A lumped parameter module calculates the instantaneous displacement chamber pressure. The second and major part of the model is dedicated to the lubrication of the three main pump sliding interfaces and considers the impact of elasto-hydrodynamic, thermal, and micro-motion effects on fluid film thickness. The final sub-model calculates the steady state temperature of the fluid in the pump housing and outlet port. Simulation results are compared to measurements taken of a commercially manufactured pump.

scholarly journals Performance Degradations of MISFET-Based Hydrogen Sensors with Pd-Ta2O5-SiO2-Si Structure at Long-Time Operation

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 777 ◽  
Author(s):  
Boris Podlepetsky ◽  
Marina Nikiforova ◽  
Andrew Kovalenko
Keyword(s):  
Experimental Data ◽  
Time Dependence ◽  
Performance Degradation ◽  
Operating Conditions ◽  
Hydrogen Sensors ◽  
Time Operation ◽  
Long Time ◽  
Degradation Degree ◽  
Two Stages

There are presented the generalized results of studies of performance degradation of hydrogen sensors based on MISFET with structure Pd-Ta2O5-SiO2-Si. It was shown how responses’ parameters change during long-term tests of sensors under repeated hydrogen impacts. There were found two stages of time-dependence response’ instability, the degradation degree of which depends on operating conditions, hydrogen concentrations and time. To interpret results there were proposed the models, parameters of which were calculated using experimental data. These models can be used to predict performances of MISFET-based devices for long-time operation.

scholarly journals Methodology for Selecting the Operating Conditions of a Vibration Generator Used in the Hot-Dip Galvanizing Process

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2042
Author(s):  
Wojciech Kacalak ◽  
Igor Maciejewski ◽  
Dariusz Lipiński ◽  
Błażej Bałasz
Keyword(s):  
Simulation Model ◽  
Asynchronous Motor ◽  
Experimental Tests ◽  
Suspension System ◽  
Operating Conditions ◽  
Test Results ◽  
Forced Simulation

A simulation model and the results of experimental tests of a vibration generator in applications for the hot-dip galvanizing process are presented. The parameters of the work of the asynchronous motor forcing the system vibrations were determined, as well as the degree of unbalance enabling the vibrations of galvanized elements weighing up to 500 kg to be forced. Simulation and experimental tests of the designed and then constructed vibration generator were carried out at different intensities of the unbalanced rotating mass of the motor. Based on the obtained test results, the generator operating conditions were determined at which the highest values of the amplitude of vibrations transmitted through the suspension system to the galvanized elements were obtained.

Modeling and Experimental Validation of the Effective Bulk Modulus of a Mixture of Hydraulic Oil and Air

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Hossein Gholizadeh ◽  
Doug Bitner ◽  
Richard Burton ◽  
Greg Schoenau
Keyword(s):  
Experimental Data ◽  
Bulk Modulus ◽  
Theoretical Models ◽  
Operating Conditions ◽  
Air Bubbles ◽  
Pressure Sensitivity ◽  
Hydraulic Oil ◽  
Effective Bulk Modulus ◽  
Experimental Apparatus ◽  
Major Factors

It is well known that the presence of entrained air bubbles in hydraulic oil can significantly reduce the effective bulk modulus of hydraulic oil. The effective bulk modulus of a mixture of oil and air as pressure changes is considerably different than when the oil and air are not mixed. Theoretical models have been proposed in the literature to simulate the pressure sensitivity of the effective bulk modulus of this mixture. However, limited amounts of experimental data are available to prove the validity of the models under various operating conditions. The major factors that affect pressure sensitivity of the effective bulk modulus of the mixture are the amount of air bubbles, their size and the distribution, and rate of compression of the mixture. An experimental apparatus was designed to investigate the effect of these variables on the effective bulk modulus of the mixture. The experimental results were compared with existing theoretical models, and it was found that the theoretical models only matched the experimental data under specific conditions. The purpose of this paper is to specify the conditions in which the current theoretical models can be used to represent the real behavior of the pressure sensitivity of the effective bulk modulus of the mixture. Additionally, a new theoretical model is proposed for situations where the current models fail to truly represent the experimental data.

A Spray-Droplet Model for Diesel Combustion

1969 ◽  
Vol 184 (10) ◽  
pp. 28-35 ◽  
Author(s):  
J. Shipinski ◽  
P. S. Myers ◽  
O. A. Uyehara
Keyword(s):  
Experimental Data ◽  
Diesel Engine ◽  
Heat Release ◽  
Engine Speed ◽  
Chamber Pressure ◽  
Gas Temperature ◽  
Single Droplet ◽  
Burning Rates ◽  
Burning Model ◽  
The One

A spray-burning model (based on single-droplet theory) for heat release in a diesel engine is presented. Comparison of computations using this model and experimental data from an operating diesel engine indicate that heat release rates are not adequately represented by single-droplet burning rates. A new concept is proposed, i.e. a burning coefficient for a fuel spray. Comparisons between computations and experimental data indicate that the numerical value of this coefficient is nearly independent of engine speed and combustion-chamber pressure. However, the instantaneous value of the spray burning coefficient is approximately proportional to the instantaneous mass-averaged cylinder gas temperature to the one-third power.

Preliminarily Design of Supercritical CO2 Compression Test System

2021 ◽  
Author(s):  
Geng Teng ◽  
Laijie Chen ◽  
Xin Shen ◽  
Hua Ouyang ◽  
Yubo Zhu ◽  
...  
Keyword(s):  
Simulation Model ◽  
Compression Test ◽  
Thermodynamic Model ◽  
Supercritical Co2 ◽  
Operating Performance ◽  
Test System ◽  
Operating Conditions ◽  
Working Fluid ◽  
Stable Operation ◽  
Test Loop

Abstract The centrifugal compressor is the core component of the supercritical carbon dioxide (SCO2) power cycle. It is essential to carry out component-level experimental research on it and test the working characteristics of the compressor and its auxiliary equipment. Building an accurate closed-loop simulation model of closed SCO2 compression loop is a necessary preparation for selecting loop key parameters and establishing system control strategy, which is also an important prerequisite for the stable operation of compressor under test parameters. In this paper, the thermodynamic model of compressor, pre-cooler, orifice plate and other components in supercritical CO2 compression test system is studied, and the simulation model of compression test system is established. Moreover, based on the system enthalpy equations and physical property model of real gas, the compressor, pre-cooler and other components in the test loop are preliminarily designed by using the thermodynamic model of components. Since the operating conditions are in the vicinity of the critical point, when the operating conditions change slightly, the physical properties of the working fluid will change significantly, which might have a greater impact on the operating performance of the system. So the operating performance and the parameter changes of key nodes in the test loop under different operating conditions are calculated, which will provide theoretical guidance for the construction of subsequent experimental loops.

A Practical Approach to Expedite a Pore to Process Simulation Model for a Rich Gas Condensate Reservoir – Case Study

2021 ◽  
Author(s):  
Mohamed Ibrahim Mohamed ◽  
Ahmed Mahmoud El-Menoufi ◽  
Eman Abed Ezz El-Regal ◽  
Ahmed Mohamed Ali ◽  
Khaled Mohamed Mansour ◽  
...  
Keyword(s):  
Simulation Model ◽  
Production Optimization ◽  
Operating Conditions ◽  
Gas Condensate ◽  
Western Desert ◽  
Design Parameters ◽  
Compositional Approach ◽  
Process Plant ◽  
Black Oil

Abstract Field development planning of gas condensate fields using numerical simulation has many aspects to consider that may lead to a significant impact on production optimization. An important aspect is to account for the effects of network constraints and process plant operating conditions through an integrated asset model. This model should honor proper representation of the fluid within the reservoir, through the wells and up to the network and facility. Obaiyed is one of the biggest onshore gas field in Egypt, it is a highly heterogeneous gas condensate field located in the western desert of Egypt with more than 100 wells. Three initial condensate gas ratios are existing based on early PVT samples and production testing. The initial CGRs as follows;160, 115 and 42 STB/MMSCF. With continuous pressure depletion, the produced hydrocarbon composition stream changes, causing a deviation between the design parameters and the operating parameters of the equipment within the process plant, resulting in a decrease in the recovery of liquid condensate. Therefore, the facility engineers demand a dynamic update of a detailed composition stream to optimize the system and achieve greater economic value. The best way to obtain this compositional stream is by using a fully compositional integrated asset model. Utilizing a fully compositional model in Obaiyed is challenging, computationally expensive, and impractical, especially during the history match of the reservoir numerical model. In this paper, a case study for Obaiyed field is presented in which we used an alternative integrated asset modeling approach comprising a modified black-oil (MBO) that results in significant timesaving in the full-field reservoir simulation model. We then used a proper de-lumping scheme to convert the modified black oil tables into as many components as required by the surface network and process plant facility. The results of proposed approach are compared with a fully compositional approach for validity check. The results clearly identified the system bottlenecks. The model can be used to propose the best tie-in location of future wells in addition to providing first-pass flow assurance indications throughout the field's life and under different network configurations. The model enabled the facility engineers to keep the conditions of the surface facility within the optimized operating envelope throughout the field's lifetime.

Performance Characterization of a Twin Scroll Volute for Turbocharging Applications

2018 ◽  
Author(s):  
Carlo Cravero ◽  
Mario La Rocca ◽  
Andrea Ottonello
Keyword(s):  
Experimental Data ◽  
Scientific Literature ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Automatic Design ◽  
Cfd Model ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission

The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.

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