scholarly journals The Effect of Spool Displacement Control to the Flow Rate in the Piezoelectric Stack-Based Valve System Subjected to High Operating Temperature

Actuators ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 239
Author(s):  
Yu-Jin Park ◽  
Bo-Gyu Kim ◽  
Jun-Cheol Jeon ◽  
Dongsoo Jung ◽  
Seung-Bok Choi
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Operating Temperature ◽  
Control Volume ◽  
Tracking Error ◽  
Displacement Control ◽  
Structural Part ◽  
Valve System ◽  
Wide Range ◽  
Experimental Apparatus

This work investigates the effect of spool displacement control of the piezoelectric stack actuator (PSA) based valve system on the flow motion of the pressure drop and flow rate. As a first step, the governing equations of the structural parts of the displacement amplifier and spool are derived, followed by the governing equation of the fluid part considering control volume and steady flow force. Then, an appropriate size of the valve is designed and manufactured. An experimental apparatus to control the spool displacement is set up in the heat chamber and tracking control for the spool displacement is evaluated at 20 °C and 100 °C by implementing a proportional-integral-derivative (PID) feedback controller. The tracking controls of the spool displacement associated with the sinusoidal and triangular trajectories are realized at 20 °C and 100 °C. It is demonstrated that the tracking controls for the sinusoidal and triangular trajectories have been well carried out showing the tracking error less than 3 μm at both temperatures. In addition, the flow motions for the pressure drop and the flow rate of the proposed valve system are experimentally investigated. It is identified from this investigation that both pressure drop and flow rate evaluated 20 °C have been decreased up to 18% at 100 °C. This result directly indicates that the temperature effect to control performance of the structural part and fluid part in the proposed PSA based valve system is different and hence careful attention is required to achieve the successful development of advanced valve systems subjected to a wide range of the operating temperature.

An Experimental Investigation of Pressure Drop During Partial Condensation of Low Pressure Steam

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Jacques du Plessis ◽  
Michael Owen
Keyword(s):  
Pressure Drop ◽  
Cooling System ◽  
Thermal Power ◽  
Steam Pressure ◽  
Tube Length ◽  
Condenser Tube ◽  
Cooling Systems ◽  
Frictional Pressure Drop ◽  
Wide Range ◽  
Experimental Apparatus

Abstract As direct dry-cooling systems are becoming more popular for thermal power plants, there is a demand to increase the flexibility of the application and performance of these cooling systems. A novel hybrid (dry/wet) dephlegmator (HDWD) cooling system is being developed, and at this stage in the development of the HDWD, the performance analysis and optimization of the HDWD is currently subject to uncertainties in a number of parameters. One of the parameters is the confidence in the correlations to predict the steam-side pressure drop over the wide range of full to partial condensation conditions expected in the system as a result of the design. This study makes use of an experimental apparatus to measure steam pressure drop over a range of partial to full condensation inside a circular horizontal tube. The experiment is conducted by measuring the steam flow and steam pressure drop in a horizontal primary condenser tube with the presence of a secondary condenser tube. The primary condenser has a tube length of 2.5 m and an inside tube diameter of 19.3 mm similar to the proposed HDWD design. Existing correlations for pressure drop in condensing flow are compared with the results to assess the applicability of the correlations for the HDWD case. It was found that the correlation of Lockhart and Martinelli’s with the Chisholm parameter fits the experimental data the best with a mean error of ±15.6%. A parametric study also indicated that there is a prominent increase in the frictional pressure drop at low partial condensation ratios (i.e., high steam through flow) as expected with wave drag at the vapor and condensate interface due to the difference in velocity.

scholarly journals Hydraulic characteristic of collagen

2016 ◽  
Vol 33 (No. 5) ◽  
pp. 479-485 ◽  
Author(s):  
R. Žitný ◽  
A. Landfeld ◽  
J. Skočilas ◽  
J. Stancl ◽  
V. Flegl ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Limited Range ◽  
Hydraulic Characteristic ◽  
Hydraulic Characteristics ◽  
Flow Rates ◽  
Transient Flows ◽  
Wide Range ◽  
On Line ◽  
Collagenous Material

Hydraulic characteristic of collagen. Czech J. Food Sci., 33: 479–485. The hysteresis of a hydraulic characteristic while pumping an aqueous solution of collagen through a pipe at gradually increasing and decreasing flow rates (hysteresis means that the pressure drop curve during increased flow rate is above the pressure drop during decreasing flow rate) was observed. The problem was initiated by industry and by demand for an on-line recording of rheological properties of collagenous material used for extrusion of collagen casings. The Herschel-Bulkley rheological model was capable to describe rheograms in a wide range of deformation rates; however it was not able to describe and explain the hysteresis. As a possible reason thixotropic properties were identified and the hydraulic characteristic was calculated using a thixotropic generalisation of the Herschel-Bulkley model. The developed 1D numerical model can be applied for on-line modelling of transient flows of incompressible thixotropic food materials (startup flow) and at a limited range of flow rates it is also capable to describe the hysteresis of hydraulic characteristics.

Computational Simulation for Predicting Flow Through a Belleville Washer Damper Unit

2007 ◽  
Author(s):  
Anil Patel ◽  
Derek Tilley ◽  
Jos Darling
Keyword(s):  
Experimental Study ◽  
Pressure Drop ◽  
Flow Rate ◽  
Fluid Dynamic ◽  
Computational Simulation ◽  
Computational Fluid Dynamic Simulation ◽  
Attractive Alternative ◽  
Flow Area ◽  
Load Bearing ◽  
Wide Range

A Belleville washer can be best described as a non flat washer with a conical shape and a uniform cross section. They are also known as disk springs and as the name suggests they are often utilised for their load bearing capabilities. Due to their compactness along the axis of loading and a wide range of attainable load-deflection characteristics they are an attractive alternative to conventional springs. Though Belleville washers are primarily used for their load bearing capabilities, they can also be used to build a damping device; which in turn can be used as part of a suspension system. The non linear deflection of the spring makes it difficult to predict the resulting pressure-flow characteristic and as a result the damper pack is built either by an experienced operative or by a trial and improvement method. Without an analytical tool to predict the behaviour a designer cannot exploit the full functionality of this type of spring. The intension of this paper is to present research undertaken to develop a correlation which describes the pressure drop required for various flow rates when using Belleville washers as damping elements. Using existing load-deflection theory an initial model was developed to relate load with pressure and deflection with flow area which could be used to estimate flow rate. The solutions from a computer simulation showed similar trends to those found in the experimental study, but they estimated smaller pressure drops for a given flow rate. It was postulated that the exit velocity of the fluid created a region of low pressure which tended to close the opening and thus increase the pressure drop. This hypothesis was examined and confirmed with a computational fluid dynamic simulation and the results were used to modify the existing model. Analysis of the new model showed good agreement with the experimental study.

3-D Transient CFD Modeling of Pig Motion

2016 ◽  
Author(s):  
Diego Jaimes Parilli ◽  
Nelson Loaiza ◽  
Janneth García ◽  
Armando Blanco
Keyword(s):  
Pressure Drop ◽  
Numerical Models ◽  
Control Volume ◽  
Physical Models ◽  
Body Motion ◽  
Cfd Modeling ◽  
Maximum Pressure ◽  
Variable Boundary ◽  
Numerical Predictions ◽  
Wide Range

Pigging operations are common procedures for pipeline maintenance. However, questions still remain about pig dynamics due to the difficulties to accurately describe this complex phenomenon. Consequently, most predictions of pig dynamics are based on empirical knowledge deduced from experimental data and numerical models developed considering simplified physical models, without calculate transient pig-flow interaction and neglecting 3D aspect of flow dynamics. Therefore, to present an actual 3D transient model, this paper proposes a novel CFD methodology using a static mesh in a moving control volume. Forces acting on the pig are dynamically computed by a Fluid-Structure Interaction (FSI) approach; pig velocity is obtained for each time instant and it is set as a variable boundary condition. This method was validated with experimental results and it may be used to describe a wide range of rigid body motion immerse in a flow. This approach is then utilized to obtain the transient simulation of a pig launch in a straight water pipeline. Numerical predictions of the static grid method were compared with those obtained using moving mesh simulations. Results show that the pig reaches a terminal velocity higher than average flow velocity and a huge difference on predictions of maximum pressure drop (through the pig) between steady state based models and transient models. Additionally, it was simulated a 2D model to observe the differences between 2D and 3D simulations on the flow characteristics and pig motion features, which shows an important increase of the pressure drop on 3D model over 2D and high pig acceleration in the 3D simulation.

scholarly journals Thermal Analysis of Direct Liquid-Immersed Solar Receiver for High Concentrating Photovoltaic System

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Xinyue Han ◽  
Qian Wang ◽  
Jun Zheng ◽  
Jian Qu
Keyword(s):  
Solar Cells ◽  
Conversion Efficiency ◽  
Flow Rate ◽  
Triple Junction ◽  
Concentration Factor ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Dense Array ◽  
Wide Range ◽  
Solar Receiver

Concentrator solar cells that operate at high solar concentration level must be cooled. In this paper, direct liquid immersion cooling of triple-junction solar cells (InGaP/InGaAs/Ge) is proposed as a heat dissipation solution for dense-array high concentrating photovoltaic (HCPV) systems. The advantages of triple-junction CPV cells immersed in a circulating dielectric liquid and dish HCPV technology are integrated into a CPV system to improve the system electrical conversion efficiency. An analytical model for the direct liquid-immersed solar receiver with triple-junction CPV cells is presented. The main outputs of the model are the components temperatures of the receiver and the system electrical efficiency. The influence of concentration factor, mass flow rate, and inlet liquid temperature on the operating temperature of the triple-junction CPV cells and the system electrical conversion efficiency are discussed. It is shown that the system electrical conversion efficiency is very high for a wide range of operating conditions. The three operating parameters have a major effect on the operating temperature of the triple-junction CPV cells and, by extension, system output power. The flow rate selection should match concentration factor to keep the triple-junction CPV cells temperature lower and increase the electrical conversion efficiency of the dense-array HCPV system.

Thin-Film Coupled Fluid-Solid Analysis of Flow Through the Ahmed™ Glaucoma Drainage Device

2005 ◽  
Vol 127 (5) ◽  
pp. 776-781 ◽  
Author(s):  
Matthew S. Stay ◽  
Tingrui Pan ◽  
J. David Brown ◽  
Babak Ziaie ◽  
Victor H. Barocas
Keyword(s):  
Pressure Drop ◽  
Aqueous Humor ◽  
Flow Rate ◽  
Glaucoma Drainage Device ◽  
Direct Result ◽  
Variable Resistance ◽  
Drainage Device ◽  
Aqueous Humor Flow ◽  
Wide Range ◽  
Flow Through

The Ahmed™ glaucoma valve (AGV) is a popular glaucoma drainage device, allowing maintenance of normal intraocular pressure in patients with reduced trabecular outflow facility. The uniquely attractive feature of the AGV, in contrast to other available drainage devices, is its variable resistance in response to changes in flow rate. As a result of this variable resistance, the AGV maintains a pressure drop between 7 and 12mmHg for a wide range of aqueous humor flow rates. In this paper, we demonstrate that the nonlinear behavior of the AGV is a direct result of the flexibility of the valve material. Due to the thin geometry of the system, the leaflets of the AGV were modeled using the von Kármán plate theory coupled to a Reynolds lubrication theory model of the aqueous humor flow through the valve. The resulting two-dimensional coupled steady-state partial differential equation system was solved by the finite element method. The Poisson’s ratio of the valve was set to 0.45, and the modulus was regressed to experimental data, giving a best-fit value 4.2MPa. Simulation results compared favorably with previous experimental studies and our own pressure-drop∕flow-rate data. For an in vitro flow of 1.6μL∕min, we calculated a pressure drop of 5.8mmHg and measured a pressure drop of 5.2±0.4mmHg. As flow rate was increased, pressure drop rose in a strongly sublinear fashion, with a flow rate of 20μL∕min giving a predicted pressure drop of only 10.9mmHg and a measured pressure drop of 10.5±1.1mmHg. The AGV model was then applied to simulate in vivo conditions. For an aqueous humor flow rate of 1.5-3.0μL∕min, the calculated pressure drops were 5.3 and 6.3mmHg.

Pressure Drop of Liquid-Liquid Taylor Flow in Mini-Scale Tubing

2016 ◽  
Author(s):  
W. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Flow Rate ◽  
Small Scale ◽  
Flow Rates ◽  
Constant Flow Rate ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, the pressure drop of liquid-liquid segmented flow in small-scale tubing is investigated with experimental and analytical methods. A theoretical model is developed for describing the total pressure drop as a function of slug length and Capillary number. The experiments are conducted with low Reynolds number flows in horizontal, straight mini-scale tubes. A segmented (Taylor) flow is created using several low viscosity silicone oils (1, 3, 5 cSt) and water with a wide range of flow rates. The experimental setup allows the independent variation of liquid slug lengths. The liquids are injected into the mini-scale tubes at a variable (pulsed) flow rate for one liquid, and a constant flow rate for another liquid. The variation of liquid types and flow rates causes numerous combinations of Prandtl, Reynolds, and Capillary numbers to be tested. The theoretical and experimental data is presented in terms of the dimensionless groups fRe or ΔP* and Le* to predict pressure drop in liquid-liquid Taylor flow. The new experimental data agrees well with the new theoretical model of Taylor flow in miniscale tubes. The results of this paper indicate the pressure drop for Taylor flow is higher than in single-phase flow, likely due to the interfacial effects in liquid slugs.

Experimental Study of Pressure Drop-Flow Rate Characteristics of Heated Tight Porous Materials

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Yuxuan Liao ◽  
Xin Li ◽  
Wei Zhong ◽  
Guoliang Tao ◽  
Hao Liu ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Porous Materials ◽  
Flow Rate ◽  
Characteristic Temperature ◽  
Industrial Applications ◽  
Average Density ◽  
Heating Power ◽  
Electromagnetic System ◽  
Wide Range ◽  
Constant Heating

Tight porous materials are used as pneumatic components in a wide range of industrial applications. Such porous materials contain thousands of interconnected irregular micropores, which produce a large pressure drop (ΔP) between the upstream and downstream sides of the porous material when a fluid flows through it. The relationship between the pressure drop and flow rate (i.e., ΔP-G characteristics) is a very important basic characteristic. Temperature is one of the factors that affect the ΔP-G characteristics because variations in temperature change the viscosity and density of the fluid. In this study, we experimentally analyzed the ΔP-G characteristics of tight porous materials by heating them using an electromagnetic system. First, we experimentally investigated the change in the ΔP-G curve under the condition of constant heating power. Then, based on the Darcy–Forchheimer theory, we introduced an experimental method to determine the average temperature of the fluid. The results show that the temperature reaches approximately 500 K in the small flow rate range, which produces considerable changes in the ΔP-G curve. As the flow rate increases, the temperature decreases, and thus, the ΔP-G curve at constant heating power converges to the curve for the room temperature. Furthermore, we compared three porous materials with different permeability coefficients and porosities and analyzed the effect of these parameters on the ΔP-G characteristics. We also performed experiments at different downstream pressures to study the effect of the average density on the ΔP-G characteristics.

Investigation of Instability of a Pressure Compensated Vane Pump

2016 ◽  
Author(s):  
Ryan P. Jenkins ◽  
Monika Ivantysynova
Keyword(s):  
Control Volume ◽  
Operating Conditions ◽  
Working Fluid ◽  
Displacement Control ◽  
Vane Pump ◽  
Flow Rates ◽  
Wide Range ◽  
Oil Flow ◽  
Variable Displacement ◽  
Cooling And Lubrication

Currently, fixed displacement pumps are typically used to provide the oil flow required for actuation of the clutches, cooling, and lubrication of automatic transmissions. This results in significant power losses as excess flow at higher engine speeds is throttled through orifices back to the tank. Therefore, the use of variable displacement pumps to supply the required oil flow can reduce the overall fuel consumption of the vehicle by eliminating this excess flow at high engine speeds. This paper presents the development and experimental validation setup of a model for a pressure compensated pivoting-cam-type variable displacement vane pump (VDVP) that is suitable for these applications. The pump operates at low system pressures (typically ∼5 bar with maximum 20 bar) with significant amounts of entrained air present in the working fluid (typically 3% by volume at the delivery) over a wide range of input speeds (700–6000 rpm). These conditions, along with a combination of a highly dynamic flow demand and dynamically changing pressure compensation setting, result in pump instabilities and loss of controllability. Previously, high leakage flow rates were introduced into the cam displacement control volume in an attempt to stabilize the pump with limited improvements. A high fidelity simulation model of the VDVP displacement chambers and cam displacement control volume pressure development was created in MATLAB/Simulink to accurately predict pump flow rates and cam dynamics in order to investigate these instabilities and methods for increasing the controllability of the VDVP. Additionally, the model provides a platform to assess the system sensitivity to changes in fluid/air mixture ratio, vane spacing, bias spring rate, and pump outlet pressure. A modified pump that was instrumented to measure the pressure gradients within each displacement chamber at the transitions between the suction and delivery ports under realistic operating conditions is presented. The modified pump was also instrumented with a linear variable displacement transducer (LVDT) to directly measure cam position during pump operation on an experimental test bed incorporating actual control valves found in an automatic transmission.

scholarly journals Flow Rate Dependence of Ventilation

1987 ◽  
Vol 14 (1) ◽  
pp. 11-19
Author(s):  
DE Mathis
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Continuous Flow ◽  
Quantitative Model ◽  
Rate Dependence ◽  
Experimental Measurements ◽  
Flow Rates ◽  
Flow Dependence ◽  
Wide Range ◽  
Flow Pressure

AbstractA quantitative model describing the effects of puffing conditions on the level of filter ventilation was developed and evaluated. The development of the model was based on a quadratic flow-pressure drop relationship which was validated with experimental measurements for numerous plug wraps, tipping papers, and combinations of the two. This relationship was used to derive an equation describing the level of filter ventilation as a function of the flow rate of air exiting the filter. This equation was shown to accurately predict the measured ventilations of six brands of commercial cigarettes over a range of continuous flow rates. The instantaneous ventilation values predicted by the equation were utilized to model ventilation during a puff by integrating the equation with respect to flow rate over the duration of the puff. This method for predicting the effects of specific puffing conditions on ventilation was demonstrated for sinusoidally shaped puffs spanning a wide range of volume and duration. Finally, the effects on the flow dependence of ventilation of different combinations of plug wrap and tipping papers were described qualitatively based on experimental measurements of paper flow-pressure drop linearity.

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