scholarly journals Research into ultrasoic and hydrodinamic cavitation phenomena in a hydraulic system

2021 ◽  
Vol 5 (1) ◽  
pp. 33-40
Author(s):  
Jaroslaw Stryczek ◽  
Piotr Antoniak ◽  
Michal Banas ◽  
Piotr Stryczek ◽  
Oleg Yakhno ◽  
...  
Keyword(s):  
Hydraulic System ◽  
Experimental Tests ◽  
Ultrasonic Cavitation ◽  
Hydrodynamic Cavitation ◽  
Gear Pump ◽  
Visualization Method ◽  
Special System ◽  
Beneficial Effects ◽  
Transparent Objects ◽  
Flow Through

The article describes the course of the ultrasonic cavitation in a hydraulic tank and the hydrodynamic cavitation in a gear pump. The course of those phenomena was confirmed in experimental tests carried out with the use of a tank and a pump made of transparent plastics. It has been proved that the oscillator-cavitation system made according to the original project is useful to induce the phenomenon of ultrasonic cavitation. It has also been shown that the PIV visualization method, consisting in a special system of illuminating transparent objects and recording the flow through those objects with a fast camera, is useful for the studying of the cavitation phenomena. A visible interaction between the ultrasonic and the hydrodynamic cavitation was observed. The induction of ultrasonic cavitation in the tank causes degassing of the oil, and the degassed oil supplying the pump reduces the hydrodynamic cavitation in its internal channels and clearances. This is an example of beneficial effects of the ultrasonic cavitation on the operation of a pump and a hydraulic system. The presented work is an example of effective co-operation between the communities of Wroclaw University of Science and Technology and Igor Sikorsky Kiyv Politechnic Institute, National Technical University of Ukraine.

Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2009 ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 79%, and total system losses by 66%. Design equations are also derived. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly important as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency an on/off valve that was 5 times faster.

scholarly journals Soy-enriched bread, a pilot study to determine its beneficial effects in menopause

2021 ◽  
Author(s):  
Daniela Giustarini ◽  
Comasia Ricci ◽  
Ilaria Ceccarelli ◽  
Stefano Pieretti ◽  
Paolo Andre ◽  
...  
Keyword(s):  
Experimental Tests ◽  
The Body ◽  
Many Body ◽  
Beneficial Effects ◽  
Regular Consumption ◽  
Aging Women ◽  
Before And After ◽  
Quality Of Life Index ◽  
Antioxidant Parameters ◽  
History Of

Menopause is the last step in the reproductive history of a woman. The ovaries stop producing hormones and the body reacts by lowering its functions, including the neuronal one. Phytoestrogens are plant products with estrogen-like activity able to affect many body functions. The aim of the present experiment was to study the effects of 30 days of regular consumption of a soy-enriched bread containing a known amount of phytoestrogens (genistein and daidzein). Women at climacteric, within 5 years or more than 5 years of menopause, were asked to include in their diet 200 g/day of a bread containing 40 mg of phytoestrogens. The effect on common menopausal symptoms and neurophysiological, hormonal and antioxidant parameters were determined before and after 30 days through questionnaires and experimental tests. Phytoestrogens were measured in the urine. In all groups, there was a significant increase of phytoestrogens in the urine and a decrease of the classical symptoms of menopause as well as a significant improvement in attentional performance tests, the quality of life index and pain intensity. Phytoestrogens present in the soy-enriched bread, are an important supplement in aging women due to their ability to induce estrogen-like effects without the potential side effects of estrogens.

Experimental Investigation of Flowrate Irregularity in Rotary Gear Pumps

1992 ◽  
Author(s):  
G. Mimmi
Keyword(s):  
Experimental Investigation ◽  
Flow Rate ◽  
Experimental Tests ◽  
Periodic Variation ◽  
Experimental Results ◽  
Gear Pump ◽  
Gear Pumps ◽  
Hot Film ◽  
Instantaneous Flow Rate ◽  
External Gear Pump

Abstract In a previous paper the author proposed a method to reduce the periodic variation in flow rate for an external gear pump. To verify the experimental results, a series of experimental tests on a expressly realized gear pump, was carried out. The pump was equipped with relieving grooves milled into the side plates. The tests were done on a closed piping specifically realized and equipped for measuring the instantaneous flow rate of the fluid through a wedge-shaped hot film probe.

The Air Controlled Hydraulic System Design of 3201z-Type Dump Truck Lifting Mechanisms

2011 ◽  
Vol 383-390 ◽  
pp. 1202-1207
Author(s):  
Tao Ping Yan
Keyword(s):  
Hydraulic System ◽  
Hydraulic Cylinder ◽  
Dump Truck ◽  
Gear Pump ◽  
Technical Parameters ◽  
Technical Performance ◽  
System Pressure ◽  
Working Principle ◽  
The Stability ◽  
Hydraulic System Design

3201Z-type dump truck is modification desiged by EQ3208GJ dump truck chassis which the technical performance parameters are known, and using a lifting mechanism of air controlled hydraulic system. By analyzing the composition and working principle of air controlled hydraulic system and referring to similar models, the design of the tank, the limiting mechanism and power taker are conducted. By calculating the main technical parameters, including in the performances of the hydraulic cylinder and the hydraulic pump, the dump truck's special oil cylinder HG-E180X780 and gear pump CBT-E563 are selected. By the stability of the piston rod, the system pressure and cars lifting time are checked; the reasonability and safty of the design can be proved.

The Reduction of Gear Pump Pressure Ripple

1987 ◽  
Vol 201 (2) ◽  
pp. 99-106 ◽  
Author(s):  
K A Edge ◽  
B R Lipscombe
Keyword(s):  
Hydraulic System ◽  
Pressure Fluctuations ◽  
Gear Pump ◽  
Noise Levels ◽  
Flow Ripple ◽  
Flow Fluctuation ◽  
Accurate Knowledge ◽  
Airborne Noise ◽  
Pressure Ripple ◽  
Pump Pressure

Pressure fluctuations in a hydraulic system may be substantially reduced by cancelling the flow ripple produced by the pump. This paper describes a secondary flow ripple generating mechanism which introduces an equal and opposite flow fluctuation to that generated by the pump. Tests have shown that the mechanism can virtually cancel four harmonics of pressure ripple but success is dependent on an accurate knowledge of the pump flow fluctuation characteristic. This is best determined experimentally. Similar improvements can be achieved using a mechanism in a motor. This has the additional benefit of reducing torque fluctuations. The reduction in gear pump pressure ripple achieved with the mechanism has been shown to reduce overall airborne noise levels from a hydraulic system by as much as 10 dB, although the airborne noise radiated from the pump casing was not affected.

Hydraulic actuation of multi-body structures through large-scale motions. Part 2: Controller design and performance

2008 ◽  
Vol 222 (3) ◽  
pp. 365-375
Author(s):  
D T Branson ◽  
P S Keogh ◽  
D G Tilley
Keyword(s):  
Hydraulic System ◽  
Large Scale ◽  
Controller Design ◽  
Experimental Tests ◽  
Companion Paper ◽  
Design Stage ◽  
Base Level ◽  
Active Vibration ◽  
And Performance ◽  
Multi Body

This paper addresses a controller design methodology for the hydraulic actuation of non-linear multi-body systems. It takes account of system uncertainties, envisaged system changes through added mass, positioning speed requirements, and vibration control. A mathematical model developed in the companion paper, Part 1, describes an experimental multi-body structure that is actuated by a hydraulic system. It is used to generate H∞-based position and active vibration controllers to meet the actuation requirements at the design stage. Experimental tests were undertaken with the developed H∞ controllers to demonstrate their accuracy and stability of motion control. The results are compared to ‘base level’ tests completed using a more traditional proportional-integral (PI) controller. In contrast with the instability experienced using PI control, the design process associated with the H∞ controllers ensures accurate closed loop stability over the range of system variations.

Research on Floating Moment Balancing Mechanism of a Gear Pump's Asymmetric Floating Plate with a V-Shaped Groove

2013 ◽  
Vol 415 ◽  
pp. 555-558
Author(s):  
An Lin Wang ◽  
Xiao Lu Zhang ◽  
Xue Wen Shan ◽  
Wei Liu
Keyword(s):  
Flow Field ◽  
Structural Characteristics ◽  
Evaluation Criteria ◽  
Internal Flow ◽  
Experimental Tests ◽  
Gear Pump ◽  
Balance Performance ◽  
Floating Plate ◽  
Gear Pumps ◽  
Groove Structure

Symmetrical floating plate of the high pressure and large displacement gear pump in rated conditions is inability to achieve the floating moment balance. To solve this problem, a new balancing mechanism is presented in this paper, which is asymmetric with a V-shaped groove structure on its driven side, called asymmetric balancing mechanism. Compared with traditional symmetric balancing mechanism, the floating plate with asymmetric balancing mechanism the can the coupling problem between the gear shaft and gear inner flow field through its own asymmetrical structure, so that the gear pumps internal flow field was the symmetrical distribution. According to the structural characteristics of the floating plates, Parameterized moment model based on discrete feature points was established. Theoretical analysis and experimental tests show the result , when suffered floating moment as evaluation criteria, in rated conditions, compared with the traditional symmetrical balancing mechanism one, that the balance performance of the floating plate with V-shaped groove asymmetric balancing mechanism improve by 41.42%.

scholarly journals Experimental and Numerical Studies of Hydrodynamics of Gas Flow through Orthogonal Networks

2018 ◽  
Author(s):  
Grzegorz Wałowski
Keyword(s):  
Kinetic Energy ◽  
Dissipation Rate ◽  
Gas Flow ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Cfd Modeling ◽  
Numerical Studies ◽  
Isotropic Porous Material ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through

Simulation programs contain Computational Fluid Dynamics - CFD codes and are a useful tool used for gas flow through porous materials. Conducting numerical simulations allows for detailed analysis of hydrodynamic phenomena. The results of numerical modeling should always be verifiable based on experimental data. Only their compliance with the results of experimental tests is a determinant of the correctness of the applied method. As part of the work, experimental studies of hydrodynamics of gas flow through an isotropic porous material were carried out and numerical simulation for material of the same shape was used. In the CFD modeling Kolmogorov's hypothesis for the transport of kinetic energy of turbulence k and transport of dissipation rate of kinetic energy of turbulence ε was used.

scholarly journals Cavitating Flow through a Micro-Orifice

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 191 ◽  
Author(s):  
Zhi-jiang Jin ◽  
Zhi-xin Gao ◽  
Xiao-juan Li ◽  
Jin-yuan Qian
Keyword(s):  
Pressure Difference ◽  
Rapid Development ◽  
Cavitation Number ◽  
Cavitating Flow ◽  
Hydrodynamic Cavitation ◽  
Apparent Difference ◽  
Microfluidic Systems ◽  
Vapor Cavity ◽  
Exit Pressure ◽  
Flow Through

Microfluidic systems have witnessed rapid development in recent years. As one of the most common structures, the micro-orifice is always included inside microfluidic systems. Hydrodynamic cavitation in the micro-orifice has been experimentally discovered and is harmful to microfluidic systems. This paper investigates cavitating flow through a micro-orifice. A rectangular micro-orifice with a l/d ratio varying from 0.25 to 4 was selected and the pressure difference between the inlet and outlet varied from 50 to 300 kPa. Results show that cavitation intensity increased with an increase in pressure difference. Decreasing exit pressure led to a decrease in cavitation number and cavitation could be prevented by increasing the exit pressure. In addition, the vapor cavity also increased with an increase in pressure difference and l/d ratio. Results also show the pressure ratio at cavitation inception was 1.8 when l/d was above 0.5 and the cavitation number almost remained constant when l/d was larger than 2. Moreover, there was an apparent difference in cavitation number depending on whether l/d was larger than 1.

Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states when the switching times are not negligible. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 81% and total system losses by 64%. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly beneficial as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency of an on/off valve that was 4.4 times faster.

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