Cavitation in Valve-Controlled Hydraulic Actuators

1963 ◽  
Vol 30 (4) ◽  
pp. 537-546 ◽  
Author(s):  
P. K. C. Wang ◽  
J. T. S. Ma
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Close Agreement ◽  
Experimental Studies ◽  
Experimental Results ◽  
Cavity Formation ◽  
Hydraulic Actuators ◽  
Operating Modes ◽  
Analytical Work ◽  
Critical Cavitation

Results of analytical and experimental studies of cavitation in valve-controlled hydraulic actuators under various dynamic conditions are presented. The analytical work consists of deriving approximate critical cavitation conditions for various operating modes. The experimental investigation includes both a high-speed photographic study of cavity formation and tests to check the validity of the derived cavitation conditions. Close agreement between analytical and experimental results was obtained. The mechanisms governing cavity formation and cavitation effects are discussed qualitatively.

Numerical and Experimental Investigation of Secondary Flow in a High Speed Compressor Stator

1995 ◽  
Author(s):  
Y. Ohkita ◽  
H. Kodama ◽  
O. Nozaki ◽  
K. Kikuchi ◽  
A. Tamura
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Shear Flow ◽  
Secondary Flow ◽  
Total Pressure ◽  
High Speed ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Performance Recovery

A series of numerical and experimental studies have been conducted to understand the mechanism of loss generation in a high speed compressor stator with inlet radial shear flow over the span. In this study, numerical simulation is extensively used to investigate the complex three-dimensional flow in the cascades and to interpret the phenomena appeared in the high speed compressor tests. It has been shown that the inlet radial shear flow generated by upstream rotor had a significant influence on the stator secondary flow, and consequently on the total pressure loss. Redesign of the stator aiming at the reduction of loss by controlling secondary flow has been carried out and the resultant performance recovery was successfully demonstrated both numerically and experimentally.

Experimental Investigation of the Characteristics of Dynamic Cutting Process

1977 ◽  
Vol 99 (2) ◽  
pp. 410-418 ◽  
Author(s):  
M. M. Nigm ◽  
M. M. Sadek
Keyword(s):  
Experimental Investigation ◽  
Theoretical Model ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Rake Angle ◽  
Experimental Results ◽  
High Speed Photography ◽  
Cutting Coefficients

The dynamic response of the shear plane and the variations of the dynamic cutting coefficients are experimentally investigated at various values of feed, cutting speed, rake angle, clearance angle, frequency, and amplitude of chip thickness modulation. Wave generating and wave removing cutting tests, in which high-speed photography is used to investigate the geometry of chip formation, are carried out. The theoretical model of dynamic cutting developed in [1] is assessed with reference to these experimental results. A comparison between this model and previous models in relation to the experimental results is also presented.

scholarly journals Demonstrative Pronouns as Anti-Logophoric Pronouns: An Experimental Investigation

2020 ◽  
Vol 11 (2) ◽  
pp. 110-127
Author(s):  
Stefan Hinterwimmer ◽  
Andreas Brocher ◽  
Umesh Patil
Keyword(s):  
Experimental Investigation ◽  
Experimental Studies ◽  
Experimental Results ◽  
Demonstrative Pronouns

In this paper we report the results of two experimental studies in which we tested the claim of Hinterwimmer and Bosch (2017) that German demonstrative pronouns are anti-logophoric pronouns: They avoid discourse referents as antecedents that function as perspectival centers. In both experiments we tested the interpretative options of demonstrative pronouns in text segments which were either perspectivally neutral or in which the narrator’s or a topical protagonist’s perspective was foregrounded. Taken together, the experimental results are most compatible with a slightly modified version of the analysis argued for in Hinterwimmer and Bosch (2017) according to which topical discourse referents in neutral narration automatically become perspectival centers. 

Intelligent Control of Compact Multiphase Separation System (CMSS©)—Part II: Experimental Investigation

2009 ◽  
Author(s):  
V. Sampath ◽  
R. Mohan ◽  
S. Wang ◽  
L. Gomez ◽  
O. Shoham ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Control System ◽  
Intelligent Control ◽  
Experimental Studies ◽  
Free Water ◽  
Differential Pressure ◽  
Experimental Results ◽  
Separation System ◽  
System A ◽  
Cylindrical Cyclone

In this investigation, an intelligent control system has been developed for Compact Multiphase Separation System (CMSS©) which consists of integrated configurations of three compact separators, namely, Gas-Liquid Cylindrical Cyclone (GLCC©), Liquid-Liquid Cylindrical Cyclone (LLCC©) and Liquid-Liquid Hydrocyclone (LLHC). This is a two-part paper, the first part deals with the Modeling and Simulation of the CMSS© and the second part (current paper) deals with Experimental Investigation. A new dual differential pressure sensor system has been implemented and tested for GLCC©, to eliminate the error in liquid level measurement due to change in watercut. A new watercut based control system using downstream pump speed control has been designed and tested for the LLCC© system. A new cascaded control strategy for change in set-point of differential pressure ratio using underflow quality from hydrocyclone has been designed and developed. Comparison of CMSS© performance simulator and experimental results shows that the control system simulator is capable of representing the real physical system and can be used to validate the controller design. Fuzzy logic controller has been successfully implemented and tested. Experimental results show a similar trend as the dynamic simulator results for the various input conditions and scenarios. The results from theoretical and experimental studies have shown that Free Water Knock Out (FWKO) CMSS© system can be readily deployed in the field using the control system strategies designed, implemented and tested in this study. Reliability analysis for FWKO CMSS© system has been conducted. System reliability has been calculated from reliability of components and performance reliability of the system. A new protocol has been introduced to calculate performance reliability based on performance failure of the system from simulation data. This protocol has been proven to predict performance reliability of a new system which does not have prior information on failure of components or devices.

Experimental Studies on Flexure Pivot Tilting Pad Gas Bearings With Pad Radial Compliance

2007 ◽  
Author(s):  
Kyuho Sim ◽  
Aaron Rimpel ◽  
Daejong Kim
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Experimental Results ◽  
Frequency Dependent ◽  
Gas Bearings ◽  
Force Coefficients ◽  
Tilting Pad ◽  
Operation Frequency ◽  
Large Rotor ◽  
Good Agreement

This paper presents experimental studies on imbalance responses of a rotor supported by two flexure pivot tilting pad gas bearings with radial compliance. The radial compliance was aimed to accommodate large rotor centrifugal growth inherent with high speed operation. Frequency-dependent rotordynamic force coefficients calculated from developed software were used to predict critical speeds and onset speed of instability and compared with experimental results. Two results show very good agreement.

Numerical and Experimental Investigation of Secondary Flow in a High-Speed Compressor Stator

1997 ◽  
Vol 119 (2) ◽  
pp. 169-175
Author(s):  
Y. Ohkita ◽  
H. Kodama ◽  
O. Nozaki ◽  
K. Kikuchi ◽  
A. Tamura
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Shear Flow ◽  
Secondary Flow ◽  
Total Pressure ◽  
High Speed ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Performance Recovery

A series of numerical and experimental studies have been conducted to understand the mechanism of loss generation in a high-speed compressor stator with inlet radial shear flow over the span. In this study, numerical simulation is extensively used to investigate the complex three-dimensional flow in the cascades and to interpret the phenomena that appeared in the high-speed compressor tests. It has been shown that the inlet radial shear flow generated by the upstream rotor had a significant influence on the stator secondary flow, and consequently on the total pressure loss. Redesign of the stator aiming at the reduction of loss by controlling secondary flow has been carried out and the resultant performance recovery was successfully demonstrated both numerically and experimentally.

Pressure Peaks in the Hydraulic Actuator

1965 ◽  
Vol 87 (4) ◽  
pp. 953-959 ◽  
Author(s):  
D. McCloy
Keyword(s):  
Fatigue Failure ◽  
Opposite Effect ◽  
Experimental Studies ◽  
Cavity Formation ◽  
Loading Conditions ◽  
Hydraulic Actuator ◽  
Cavitation Damage ◽  
Hydraulic Actuators ◽  
Valve Overlap ◽  
Severe Loading

Results are presented of theoretical and experimental studies of the pressure peaks occurring in valve-controlled hydraulic actuators operated under severe loading conditions. Oil compressibility is shown to reduce the magnitude of these peaks. Valve overlap has the opposite effect. The possibilities of fatigue failure and cavitation damage in the actuator are discussed. The two different modes of cavity formation which occur when the valve is oscillated sinusoidally are discussed in detail.

Effect of Nanoparticles on Forming Process of Bubbles in a Nanofluid

2009 ◽  
Author(s):  
Fengmin Su ◽  
Xuehu Ma ◽  
Jiabin Chen
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Ccd Camera ◽  
Experimental Results ◽  
Forming Process ◽  
Three Phase ◽  
Insight Into

An experimental investigation was conducted to determine the effect of nanoparticles on the forming process of bubbles in the gas-liquid-nanoparticle three-phase fluidization. In the experiment, a SiO2-water nanofluid was prepared without any surfactants, and the forming process of bubbles in the nanofluid was observed by the high-speed CCD camera. The experimental results show that the diameter of the formed bubble in the nanofluid is smaller 5% than that in water, and the frequency forming bubbles in the nanofluid is higher than that in water. The investigation can provide an insight into the functionary mechanism of the bubble forming process in the gas-liquid-nanoparticles nanofluids.

Numerical and Experimental Investigation of Inward Tube Electromagnetic Forming- Electromagnetic Study

2011 ◽  
Vol 383-390 ◽  
pp. 6710-6716 ◽  
Author(s):  
Alireza Fallahi Arezoodar ◽  
Hossein Ebrahimi Haratmeh ◽  
Mohmoud Farzin
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Process Parameters ◽  
High Speed ◽  
Discharge Voltage ◽  
Electromagnetic Forming ◽  
Experimental Results ◽  
Electromagnetic Parameters ◽  
High Speed Forming ◽  
Structural Parts

A numerical simulation of high-speed forming of tubes on the die in electromagnetic forming (EMF) system is presented to study effects of some electromagnetic parameters. Simulations of electromagnetic and structural parts of EMF process are carried out. Calculated currents in this process are in agreement with experimental results measured by Rogowsky coil. But calculated and simulated currents at first peak are a little more than the experimental value. Effects of material and process parameters on bead depth are investigated in detail with this validated code. It deduced that shape of the bead is affected by discharge voltage and coil parameters. As a result, the bead depth increases with the increase of the discharge voltage and decrease of number of windings.

scholarly journals An Experimental Investigation of Coherent Structures and Induced Noise Characteristics of the Partial Cavitating Flow on a Two-Dimensional Hydrofoil

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 198
Author(s):  
Byoung-Kwon Ahn ◽  
So-Won Jeong ◽  
Cheol-Soo Park ◽  
Gun-Do Kim
Keyword(s):  
Experimental Investigation ◽  
Coherent Structures ◽  
High Speed ◽  
Dominant Role ◽  
Experimental Studies ◽  
Two Dimensional ◽  
Damage Potential ◽  
Hairpin Vortices ◽  
Cloud Cavitation ◽  
Noise Characteristics

In many practical submerged objects, various types of cavitation such as bubble, sheet, and cloud cavitation occur according to flow conditions. In spite of numerous theoretical, numerical, and experimental studies, there are still many problems to be solved such as induced noise and damage potential due to cavitation. In this paper, an experimental investigation on coherent structures and induced noise characteristics of partial cavitation on a two-dimensional hydrofoil is presented. Experiments that focused on the dynamics of cavitation clouds were conducted in a cavitation tunnel. Using high-speed visualization, the series process consisting of inception, growth, and desinence of the partial cavity was investigated. The noise generated during the process was also measured, and the correlation with the cavity pattern was examined. The results show that the periodic behavior of cavitation clouds is directly reflected in the noise characteristics. In addition, the visualization of coherent structures within the sheet and cloud cavity provides a qualitative understanding of hairpin vortices and their packets, which play a dominant role in turbulent cavitating flows.

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