Aerospace Fluid Power - FAA Regulatory History - Transport Airplane Hydraulic Systems

2019 ◽  
Author(s):  
Keyword(s):  
Fluid Power ◽  
Hydraulic Systems

Towards Direct Numerical Simulation of Compressible Orifice Flow

2013 ◽  
Author(s):  
Bernhard Manhartsgruber
Keyword(s):  
Numerical Simulation ◽  
Stationary Flow ◽  
Parameter Tuning ◽  
Good Choice ◽  
Fluid Power ◽  
Model Complexity ◽  
Hydraulic Systems ◽  
Vast Number ◽  
Lumped Parameter ◽  
Orifice Flow

Simulation methods from simple lumped parameter approaches to complex computational fluid dynamics codes have become a widely used tool in the fluid power community. Certain tasks like the predicition of flow forces on the control spools in valves or the design of port plates in axial piston pumps are usually treated by the aid of numerical simulation. Like in many other cases, the underlying principle is the control of flow by orifices. The importance of orifice flow for hydraulic systems is reflected by the vast number of publications on various aspects of orifice flow in the fluid power literature. In lumped parameter simulations, the orifice equation giving the flow rate as a square root of the pressure drop is widely used even in transient cases where it is not clear whether the flow develops fast enough to justify the assumption of stationary flow. On the other end of the model complexity spectrum computational fluid dynamcis codes are used in the fluid power community. These very complex models require a high number of parameters for the tuning of turbulence models, wall models, and the like. The quality of the results heavily dependes on a good choice for these parameters. Additionally, the vast majority of turbulent flow simulations is done with the assumption of an incompressible fluid. Very often, the results from simulations deviate heavily from measurement results and only after parameter tuning a good match between model and simulation is achieved. This paper suggests the use of direct numerical simulations for simple and prototypical geometries in order to gain a better understanding for transient orifice flows lacking the fully developed flow assumed in traditional models.

scholarly journals Simulation of a Hydraulic Load Sensing Proportional Valve

2018 ◽  
Author(s):  
Sanjar Mirzaliev ◽  
Kungratbai Sharipov
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Control Strategies ◽  
Level Of Detail ◽  
Department Of Energy ◽  
Fluid Power ◽  
Hydraulic Systems ◽  
Proportional Valve ◽  
Load Sensing ◽  
The U.S

Nowadays energy saving is a topical issue due to increasing fuel costs and this aspect is amplified by more stringent emissions regulations that impact on vehicle development. A recent study conducted by the U.S. Department of Energy shows that about five percent of the U.S. energy consumption is transmitted by fluid power equipment. Nevertheless, this study also shows that the efficiency of fluid power averages 21 percent. This offers a huge opportunity to improve the current state-of-the-art of fluid power machines, in particular to improve the energy consumption of current applications. These facts dictate a continuous strive toward improvements and more efficient solutions: to accomplish this objective a strong reduction of hydraulic losses and better control strategies of the hydraulic systems are needed. In fluid power, there exist many techniques to reduce/recover energy losses of the conventional layouts, e.g. load sensing, electrohydraulic flow matching, independent metering, etc. One of the most efficient ways to analyze these different layouts and identify the best hydraulic solution is done through virtual simulations instead of prototyping, since the latter involves higher investment costs to deliver the product into the market. However, to build a fluid power machine virtual model, some problems arise relative to different aspects, for instance: loads on actuators (both linear and rotational) are not constant and pumps are driven by a real engine whose speed depends on required torque. Furthermore, it is important to achieve higher level of detail to simulate each component in the circuit: the greater detail, the better the machine behavior is portrayed, but it obviously entails heavy impact on simulation time and computational resources. Therefore, there is a need to create mathematical model of components and systems with sufficient level of detail to easily acquire all those phenomena necessary to correctly evaluate machine performance and make modifications to the fluid power component design. In this context, a hydraulic proportional valve PVG 32 by Danfoss is taken as an object of study, its performance is analyzed with suitable mathematical model and simulation is done to observe closeness of a model to the laboratory experiment.

scholarly journals Theoretical and Experimental Studies of a Digital Flow Booster Operating at High Pressures and Flow Rates

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 211 ◽  
Author(s):  
Chenggang Yuan ◽  
Vinrea Lim Mao Lung ◽  
Andrew Plummer ◽  
Min Pan
Keyword(s):  
Energy Efficiency ◽  
High Pressure ◽  
Flow Rate ◽  
High Energy ◽  
Control Flow ◽  
Fluid Power ◽  
Analytical Models ◽  
Operating Pressure ◽  
Hydraulic Systems ◽  
Flow Rates

The switched inertance hydraulic converter (SIHC) is a new technology providing an alternative to conventional proportional or servo-valve-controlled systems in the area of fluid power. SIHCs can adjust or control flow and pressure by means of using digital control signals that do not rely on throttling the flow and dissipation of power, and provide hydraulic systems with high-energy efficiency, flexible control, and insensitivity to contamination. In this article, the analytical models of an SIHC in a three-port flow-booster configuration were used and validated at high operating pressure, with the low- and high-pressure supplies of 30 and 90 bar and a high delivery flow rate of 21 L/min. The system dynamics, flow responses, and power consumption were investigated and theoretically and experimentally validated. Results were compared to previous results achieved using low operating pressures, where low- and high-pressure supplies were 20 and 30 bar, and the delivery flow rate was 7 L/min. We concluded that the analytical models could effectively predict SIHC performance, and higher operating pressures and flow rates could result in system uncertainties that need to be understood well. As high operating pressure or flow rate is a common requirement in hydraulic systems, this constitutes an important contribution to the development of newly switched inertance hydraulic converters and the improvement of fluid-power energy efficiency.

Design and Testing of Novel Hydraulic Pump/Motors to Improve the Efficiency of Agricultural Equipment

2017 ◽  
Vol 60 (6) ◽  
pp. 1809-1817
Author(s):  
Farid Breidi ◽  
Jordan Garrity ◽  
John Lumkes
Keyword(s):  
Agricultural Sector ◽  
Energy Savings ◽  
Fluid Power ◽  
System Level ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Agricultural Equipment ◽  
Load Height ◽  
Variable Displacement ◽  
The Impact

Abstract. Hydraulic systems are prevalent in agricultural machinery and equipment and can be found transmitting power for vehicle drive wheels, powering attachments, and controlling motion (booms, steering, load height, etc.). Agricultural applications of fluid power have advanced in terms of capability and efficiency, but opportunities remain for significant improvements in efficiency, noise reduction, and reliability. The average system-level hydraulic efficiency of current mobile agricultural machines is only 21.1%. Because nearly all hydraulic systems use pumps to convert engine power to fluid power, improving the efficiency of the pumps (and motors when used as actuators) significantly impacts the system efficiency. This work examines the impact of using more efficient digital pump/motors to improve the overall efficiency of agricultural equipment, such as tractors, harvesters, planters, fertilizers, sprayers, and attachments. Maintaining higher pump/motor efficiency throughout the operating range is the central principal for the energy savings. Currently used variable-displacement pumps have low efficiencies at low displacement levels due to constant losses that do not scale with the power produced. Digital pump/motors minimize these inefficiencies because energy losses scale more closely with the power produced. Experimental results indicate an average efficiency of 85% when operating at 20% to 100% displacement. This efficiency is 15% to 20% higher on average than with current variable-displacement axial piston pumps. This study demonstrates that achieving this improvement in the efficiency of the pump/motors used in tractors and harvesters alone would conservatively save $61.7 million worth of energy annually for end users in the U.S. agricultural sector. Keywords: Agricultural equipment, Digital hydraulics, Efficiency improvement, Hydraulic pump/motor.

Special Issue on Sustainable Design for Hydraulic Systems

2012 ◽  
Vol 6 (4) ◽  
pp. 409-409
Author(s):  
Yutaka Tanaka ◽  
Hiroshi Yoshinada
Keyword(s):  
Power Systems ◽  
Industrial Development ◽  
New Technologies ◽  
Sustainable Design ◽  
Industrial Applications ◽  
Fluid Power ◽  
Hydraulic Systems ◽  
Human Beings ◽  
Special Issue ◽  
Water Hydraulics

Given the high human impact on the environment, whether intentional or not, the world now faces a situation in which industrial development cannot proceed further without harmony among human beings and the environment. Hydraulic technologies have matured in the last decade and new technologies have emerged related to information technology, energy saving, mechatronics, and water hydraulics. It is our view that innovations in hydraulic technology involving sustainable design for hydraulic systems are essential for sustainably developing fluid power technology. One reason for this special issue on Sustainable Design for Hydraulic Systems is to encourage incremental breakthroughs in research based upon existing foundations. Another reason is to expand coordination and cooperation among academic and industrial researchers and institutions to realize these innovations. This special issue covers recent developments in hydraulic technologies, including water hydraulics and functional fluids, basic research, applications and case studies. State-of-the-art papers on hydraulic systems and components place special emphasis on industrial applications and their engineering background. All of the papers in this special issue are of great interest and value in sustainably designing fluid power systems, and we are sure that these papers will contribute much to the further development of fluid power technology. We sincerely thank the authors for their submissions and the reviewers for their invaluable efforts, without which this special issue would not have been possible. We are most grateful to all who have contributed their time and effort to ensuring the success of this special issue.

Risk-Based Comparative Study of Fluid Power Pitch Concepts

2017 ◽  
Author(s):  
Jesper Liniger ◽  
Henrik C. Pedersen ◽  
Mohsen Soltani
Keyword(s):  
Fault Tree Analysis ◽  
Fluid Power ◽  
Normal Operation ◽  
Hydraulic Systems ◽  
Conventional System ◽  
Supply Circuit ◽  
Closed Type ◽  
Increased Risk ◽  
Criticality Analysis ◽  
Field Failure

Proper functioning of the pitch system is essential to both normal operation and safety critical shut down of modern multi megawatt wind turbines. Several studies on field failure rates for such turbines show that pitch systems are a major contributor to failures which entails an increased risk. Thus, more reliable and safe concepts are needed. A review of patents and patent applications covering fluid power pitch concepts, reveals that many propose closed-type hydraulic systems. This paper proposes a closed-type concept with a bootstrap reservoir. In contrary to a conventional system where a common supply delivers to cylinder drives mounted at each blade, the concept using bootstraps are fully contained in the rotating hub and act as standalone actuators. Clear advantages of such systems are a reduction of high pressure leakage paths, but in turn more components are used for each supply circuit. To allow for comparison, this paper deals with a risk-based analysis of these two types of pitch concepts. The risk-based analysis is conducted according to a qualitative failure analysis method which is verified against recent field failure data for hydraulic pitch systems. The method combines Fault Tree Analysis and Failure Mode and Effect Criticality Analysis in a systematic framework that lowers the bias issues normally encountered for qualitative studies. Under the assumption of similar components, the results indicate an equal risk of the two concepts. A decreased reliability is seen for the bootstrap concept due to additional components in the supply circuit compared to the conventional system. It is noted that careful selection of high reliable pumps and relief valves may significantly reduce risk and increase reliability of the bootstrap concept.

Transmission of Fluid Power by Pulsating-Flow (P-F) Concept in Hydraulic Systems

1966 ◽  
Vol 88 (2) ◽  
pp. 316-321 ◽  
Author(s):  
Cheng-Kuo Weng
Keyword(s):  
Dynamic Response ◽  
Hydraulic System ◽  
Power Transmission ◽  
Pulsating Flow ◽  
Fluid Power ◽  
Experimental Investigations ◽  
System Efficiency ◽  
Test Results ◽  
Hydraulic Systems ◽  
Line Loss

Theoretical and experimental investigations have been made on fluid-power transmission in hydraulic systems by pulsating flow. In particular, the system efficiency and the viscosity effect on the dynamic response of pulsating flow in the fluid line have been studied. Test results on the fluid-line dynamic response and on the system efficiency that obtained from the line-loss test setup and the miniaturized P-F hydraulic system setup, respectively, are presented.

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