Fluid Piston Research Articles

A comprehensive optimal design method for magnetorheological dampers utilized in DMU power package

The diesel multiple unit (DMU) has been widely used in high-speed railway service due to its flexibility and economy. Considering the broadband and complex vibration generated by DMU power package, the advanced semi-active suspension with magnetorheological (MR) dampers is introduced to promote anti-vibration performance. In this work, a comprehensive optimal design approach for MR damper used in DMU power package is proposed. Quasi-static modeling process is conducted to obtain MR damper's low-frequency outputs, while its high-frequency damping forces are calculated by physical modeling considering the fluid compressibility and piston assembly inertia. Then the objective functions and optimization variables are determined. Based on response surface and linear correlation analysis, the influence of the optimal variables on the objective functions is discussed. Using reference-point based nondominated sorting approach (NSGA-III), the evolutionary many-objective optimization is conducted. In addition, magnetic design is incorporated into the optimal process to ensure the magnetic flux density in the effective working area. Finally, an optimized MR damper prototype is manufactured and tested. By comparing the experimental damping force with calculated results in both low-frequency and high-frequency ranges, the effectiveness of the presented optimal method for MR dampers is validated.

Development and experimental investigation of a novel solar-powered cooling system

The development of novel and improvement of existing technologies for utilising solar thermal energy for cooling purposes traditionally attracts increased attention in both industry and academia. This work presents the development of a novel cooling system with a simple design and direct utilisation of solar thermal energy. The cooling system combines a liquid piston engine and cooling machine and is driven by an evacuated tube solar collector. A prototype of such the system was designed, built and tested in laboratory conditions using a solar radiation simulator. Variations in pressures, temperatures, and the fluid piston oscillation amplitudes in the system during its operation were recorded, and the indicated power of the engine and cooling capacity of the system were determined for a range of operation and design parameters. For the heat input range of 700–900 W and the constant temperature of the cooling water equal to 26.0 °C, the engine indicated power and cooling capacity of the system varied in the range of 70.0–88.0 and 51.0–61.0 W. The corresponding indicated efficiency of the engine and cooling system were in the range of 10.0–9.7 and 7.2–6.7%. The temperature in the cooling chamber was registered in the range of 20.0–18.2 °C at an ambient temperature of 24.0 °C. The COP of the cooling machine decreased from 0.71 to 0.69. The system performance improved in tests with a constant heat input (700 W) and reducing cooling water temperature. For cooling water temperature reduction from 26.0 to 18.0 °C, the engine indicated power and cooling capacity of the system varied in the range of 70.0–111.9 and 51.0–72.0 W. The corresponding indicated efficiency of the engine and cooling system were in the range of 10.0–16.0 and 7.2–10.3%. The COP of the cooling machine decreased from 0.71 to 0.64. The temperature in the cooling chamber was registered in the range of 20.0–14.4 °C at an ambient temperature of 24.0 °C. Experimental results obtained using the system's initial design demonstrate that the engine has efficiency comparable to low-temperature steam and Organic Rankine Cycle turbines. The Coefficient of Performance of the system is similar to that of single-stage absorption chillers.

Вплив повздовжньо-динамічних навантажень на міцність гальмової важільної передачі візка вагона, обладнаного новим концептом упряжного пристрою

Досліджено повздовжню навантаженість вантажного поїзда, обладнаного новими концептами упряжного пристрою. Встановлено, що використання концепту упряжного пристрою дозволяє знизити повздовжню навантаженість поїзда майже на 30% у порівнянні з типовою схемою взаємодії локомотива з вагонами. Проведено розрахунок на міцність гальмової важільної передачі вантажного вагона, обладнаного новим концептом упряжного пристрою. При цьому максимальні еквівалентні напруження в елементах гальмової важільної передачі нижчі майже на 35% у порівнянні з типовою схемою Проведені дослідження сприятимуть створенню інноваційних конструкцій рухомого складу з покращеними техніко-економічними та динамічними показниками.

Fatty acid profile of pecan nut oils obtained from pressurized n-butane and cold pressing compared with commercial oils.

This short note compares the chemical profile of pecan nut oil samples obtained from pressurized n-butane and cold pressing with two commercial oils. The conventional cold pressing technique yielded 58.9wt%, while pressurized n-butane yielded from 53 to 65wt%, being the highest yield at 55°C, and pressure of 40bar. The n-butane behaves nearly like a piston fluid within the experimental conditions used. The results showed that the extraction variables had a slight influence on the fatty acid composition of the samples. Extraction with n-butane thus showed to be a promising alternative technique to conventional extraction methods, as very mild operating conditions and eco-friendly solvent can be used to provide good results without any residues in the final product.

Design and construction of a two-phase fluid piston engine based on the structure of fluidyne

Engines that extract energy from low-grade heat sources, e.g., from other processes, have received considerable attention recently. The use of Fluidyne, which is a liquid piston Stirling engine, is quite popular. Herein, we explore the use of liquid-to-vapor phase change in a Fluidyne. This provides two considerable differentiators; (1) exploitation of very low temperature difference ΔT≈30 K, and (2) relatively low temperature ΔT≈330 K heat sources, for producing mechanical work, and thus electrical energy. The influence of three operating parameters, i.e., input heat flux, working fluid, and filling ratio, on the performance of the engine was characterized. Their optimum values, which yield the best efficiency of the engine, were determined. Increasing the input heat flux led to enhanced energy production. The highest performance was achieved when Acetone was used as the working fluid, attributed to Acetone's lower evaporation temperature, viscosity, and enthalpy of evaporation. A filling ratio of 18% resulted in the highest performance. The efficiency of the engine was compared to Carnot efficiency.

A novel small dynamic solar thermal desalination plant with a fluid piston converter

An innovative small dynamic water desalination plant was developed and tested under laboratory conditions. The system is a combination of a heat pipe evacuated tube solar collector, conventional condenser and novel fluid piston converter. Saline water is boiled and turned into vapour in the manifold of the solar collector. A small fraction of the solar energy supplied to the plant is used to drive the fluid piston converter. Oscillations of the fluid piston periodically change the volume and pressure in the plant. For the duration of approximately half of the periodic cycle the pressure in the plant drops below the atmospheric level causing flash boiling of saline water in the manifold of the solar collector. Generated vapour is turned into fresh water in the condenser which is surrounded by a cooling jacket with saline water. The flash boiling effect improves the fresh water production capacity of the plant. Additionally, the fluid piston converter drives a pump which provides lifting of saline water from a well and pumps this through the cooling jacket of the condenser to a saline water storage tank. This tank replenishes saline water in the manifold of the solar collector. Experimental investigations demonstrated the saline water self-circulation capability of the plant and increase in the fresh water production compared to the static mode of operation. Experimental data was also used to calibrate the mathematical model of the plant. Comparison of theoretical and experimental information demonstrates that the model accurately predicts the performance of the plant. The proposed novel system with greater fresh water production capacity has a simple design and is easy to manufacture using low cost materials and therefore can be mass deployed for small scale saline water pumping and desalination across different regions with the relatively high solar radiation and shortage in the drinking water supply.

Controlled cargo handling with piston fluid for pressurized liquid CO2 carrier

Abstract This study proposed a concept of the cargo handling system to load the pressurized liquid CO2 into the CO2 carrier and to offload the cargo out of the carrier with the piston fluid in a controlled way. The carrier was designed to transport a large amount of the captured CO2 in liquid phase. The cargo containment system consisted of pressure vessels to withstand the elevated pressure condition. Employment of the piston fluid enabled the pressurized liquid CO2 to enter and leave the cargo vessels without phase change or evaporation of the cargo. An increased loading and offloading rate seemed to cause generation of emulsion droplets in the interface of the piston liquid and the cargo. The droplets were separated into the cargo and the piston liquid by a conventional separator. Fresh water was considered excellent piston liquid since it was easily available and immiscible with the liquid CO2. As the cargo temperature decreased, CO2 gas was found to serve as the piston gas.

Research of Surface Roughness of Fluid Piston Rod Based on the Abrasive Belt Grinding

The method of abrasive belt finishing slender piston rod was proposed in this paper, which based on low surface roughness weaknesses of low rigidity slender piston rod in the grinding process. And the ralation between the surface roughness and the grinding parameters was analyzed by the experiment research. The research result has a reasonably guidance for the actual manufacturing process.

Features of deformation of poroelastic media with low structural strength

Many natural and technological processes are associated with deformation and fracture of saturated or being saturated poroelastic media. Among such processes one can mention fluid soaking through a dam, fluid inflow to the cracks of hydraulic fracture, polishing using porous materials and special fluids, flow in catalytic pellets. All these processes are accompanied by deformation and fracture of a matrix with fluid flow. The effects at the interface porous body–fluid are essential for the processes. The specific features of deformation of poroelastic media with low structural strength are considered in this paper. The compressibility of the matrix skeleton is larger as compared to the compressibility of the saturating fluid in such media. It is shown that the oozing of the fluid at the surface of the poroelastic medium occurs in the consolidated flow regime under the action of `fluid piston' like loads if the structural strength of the medium is low. This result is obtained for both plane (deformation of a layer or halfinfinite medium) and centrally symmetric (deformation of a sphere) problems.

An experimental model investigation of the opening of a collapsed untethered pulmonary airway.

We developed an essentially two-dimensional planar benchtop model of an untethered collapsed airway to investigate the influence of fluid properties (viscosity, mu and surface tension, gamma) and the structural characteristics (effective diameter, D, longitudinal tension, T, and fluid film thickness, H) on airway reopening. This simplified model was used to quantify the relationship between wall deformation and meniscus curvature during reopening. We measured the pressure (P) required to move the meniscus at a constant velocity (U), and found the dimensionless post-startup pressure (PD/gamma) increased monotonically with the capillary number (Ca = microU/gamma). Startup pressures depend on the fluid viscosity and piston acceleration, and may significantly increase reopening pressures. Consistently stable steady-state pressures existed when Ca > 0.5. D was the most dominant structural characteristics, which caused an increase in the post-startup pressure (P) for a decrease in D. An increase in H caused a slight decrease in the reopening pressure, but a spatial variation in H resulted in only a transient increase in pressure. T did not significantly affect the reopening pressure. From our planar two-dimensional experiments an effective yield pressure of 3.69 gamma/D was extrapolated from the steady-state pressures. Based on these results, we predicted airway pressures and reopening times for axisymmetrically collapsed airways under various disease states. These predictions indicate that increasing surface tension (as occurs in Respiratory Distress Syndrome) increases the yield pressure necessary to reopen the airways, and increasing viscosity (as in cystic fibrosis) increases the time to reopen once the yield pressure has been exceeded.

Fluoroalkylene ether silicate/Viton GLT blends: An approach toward improved low temperature flexibility

AbstractLow molecular weight fluoroalkylene ether silicate (FES) polymers demonstrating glass transition temperatures of −82°C to −91°C were obtained from the condensation polymerization of fluoroether bisdimethyl carbinols and bis(dimethylamino)methyl vinyl and dimethyl silane derivatives. Peroxide cure reactivity through the pendant vinyl moieties was demonstrated. In an effort to improve the low temperature flexibility of a peroxide curable fluorocarbon elastomer (Viton GLT from Du‐Pont), blends were prepared using the FES material as an additive cocuring plasticizer. Temperature retraction tests demonstrated an optimum 5°C (9°F) improvement in low temperature flexibility. The optimum blend formulation employed FES polymers with vinyl cure site concentrations ranging from 2.35 to 2.70 mol %. The optimum blend formulation maintained the strength and low compression set properties of the Viton GLT standard. These properties reflect sufficient cocuring between the FES and Viton GLT components to provide physical properties adequate for o‐ring seal application. o‐Ring seal evaluations in Freon E6.5 fluid (rod and piston seal tests) demonstrated some seal enhancement and comparable durability to standard Viton GLT o‐rings.

Optical Fabrication of a Large Lightweight Mirror of Unusual Shape

A large, ultralightweight Cer-Vit mirror of oblong shape has been optically polished to a surface irregularity of 0.060 rms, where = 0.633 urn. Although its major dimension is 193 cm, its finished weight is only 97 kg. The nonconventional fabrication methods required by its light weight, unusual aperture shape, relatively steep curvature, and excep tionally large diameter-to-thickness ratio are described. A 64-point fluid piston mount employed to support the mirror both for optical fabrication and for interferometric test ing is also described. Techniques specially developed to produce both the mirror blank and the final optical surface demonstrate significant advances in the manufacture of large, very lightweight glassy mirrors of high optical quality.

M. Cailletet's Pump for Condensing Gas

AT page 308 of your last number you mention a pump invented by M. Cailletet for condensing gases, in which he uses mercury as a fluid piston, in order to fill every interstice of the pump barrel, and so expel the last atom of gas; of course, in this case, he would use an ordinary plunger pump, with both the inlet and outlet valves at the top, and the proper quantity of mercury in the barrel, so as to fill it completely in the downstroke of the plunger or piston.