Simulated and Experimental Analysis of a Log Crane With Conventional and Direct Driven Hydraulics

Abstract The present paper compares the efficiency and dynamic behavior of a log crane while using two alternative transmissions. Firstly, the conventional mobile hydraulic valves with a load-sensing pump is used, and secondly, a novel electric-hydraulic energy converter and a direct driven hydraulic actuator is used. By applying lumped parameter models and the theory of centralized pressure, the hydraulic system models are constructed in MATLAB & Simulink environment. MathWorks Simscape Multibody is used in modeling of the multi-body system of the crane. The results of the simulation models are compared with those measured in the laboratory. Based on the verification results, such modes of operation in which the agreement between simulated results is the closest are selected for further investigation. The effectiveness of the system equipped with an electro-hydraulic converter is compared with that of the conventional system with a load sensing pump. Detailed models for components are given in the paper, and the results are discussed based on what obtained through simulation and experiments. The electric-hydraulic converter used in direct driven circuit is a novel prototype developed at LUT University. It has good power stiffness, and it provides good torque properties in a wide RPM area. The prototype is used in operating the lift or tilt cylinder, which is altered by using fast switching valves. The actual test circuit does not have electric storage. The ability of the converter to recover potential energy from the lifting system inertia is approximated in the efficiency comparisons.

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Modelling and Validation of Cavitating Orifice Flow in Hydraulic Systems

Sustainability ◽

10.3390/su13137239 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7239

Author(s):

Paolo Casoli ◽

Fabio Scolari ◽

Massimo Rundo

Keyword(s):

Lumped Parameter Model ◽

Hydraulic Systems ◽

Vena Contracta ◽

Lumped Parameter ◽

Lumped Parameter Models ◽

Orifice Flow ◽

Computational Fluid Dynamics Cfd ◽

Set Up ◽

Cfd Method ◽

Hydraulic Valves

Cavitation can occur at the inlet of hydraulic pumps or in hydraulic valves; this phenomenon should be always avoided because it can generate abnormal wear and noise in fluid power components. Numerical modeling of the cavitation is widely used in research, and it allows the regions where it occurs more to be predicted. For this reason, two different approaches to the study of gas and vapor cavitation were presented in this paper. In particular, a model was developed using the computational fluid dynamics (CFD) method with particular attention to the dynamic modeling of both gaseous and vapor cavitation. A further lumped parameter model was made, where the fluid density varies as the pressure decreases due to the release of air and the formation of vapor. Furthermore, the lumped parameter model highlights the need to also know the speed of sound in the vena contracta, since it is essential for the correct calculation of the mass flow during vaporization. A test bench for the study of cavitation with an orifice was set up; cavitation was induced by increasing the speed of the fluid on the restricted section thanks to a pump located downstream of the orifice. The experimental data were compared with those predicted by CFD and lumped parameter models.

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Inferring transit time distributions from atmospheric tracer data: Assessment of the predictive capacities of Lumped Parameter Models on a 3D crystalline aquifer model

Journal of Hydrology ◽

10.1016/j.jhydrol.2015.03.055 ◽

2015 ◽

Vol 525 ◽

pp. 619-631 ◽

Cited By ~ 17

Author(s):

J. Marçais ◽

J.-R. de Dreuzy ◽

T.R. Ginn ◽

P. Rousseau-Gueutin ◽

S. Leray

Keyword(s):

Transit Time ◽

Lumped Parameter ◽

Lumped Parameter Models ◽

Crystalline Aquifer ◽

Data Assessment ◽

Atmospheric Tracer

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Lumped parameter models for two-ventricle and healthy and failing extracardiac Fontan circulations

Mathematical Medicine and Biology A Journal of the IMA ◽

10.1093/imammb/dqab012 ◽

2021 ◽

Author(s):

Matthew G Doyle ◽

Marina Chugunova ◽

S Lucy Roche ◽

James P Keener

Keyword(s):

Single Ventricle ◽

Left Ventricular ◽

Sensitivity Analyses ◽

Surgical Strategies ◽

Lumped Parameter ◽

Lumped Parameter Models ◽

Fontan Failure ◽

Existence Of Periodic Solutions ◽

Mathematical Definitions ◽

Extracardiac Fontan

Abstract Fontan circulations are surgical strategies to treat infants born with single ventricle physiology. Clinical and mathematical definitions of Fontan failure are lacking, and understanding is needed of parameters indicative of declining physiologies. Our objective is to develop lumped parameter models of two-ventricle and single-ventricle circulations. These models, their mathematical formulations and a proof of existence of periodic solutions are presented. Sensitivity analyses are performed to identify key parameters. Systemic venous and systolic left ventricular compliances and systemic capillary and pulmonary venous resistances are identified as key parameters. Our models serve as a framework to study the differences between two-ventricle and single-ventricle physiologies and healthy and failing Fontan circulations.

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