Length Of Liquid Column Research Articles

Gas-driven triboelectric nanogenerator for mechanical energy harvesting and displacement monitoring

Gas as an energy carrier has been widely studied, ranging from small bubble motions to steam strike turbines. Despite the remarkable results, fewer studies have investigated the gas-driven liquid column movement commonly used in hydraulic systems, oil extraction, and other fields. Herein, we proposed a gas-driven triboelectric nanogenerator (GD-TENG) with liquid column motion for mechanical energy harvesting and displacement monitoring. When the gas drives a single liquid column to move inside a polytetrafluoroethylene (PTFE) tube, the solid-liquid interface of the GD-TENG can achieve efficient sliding friction and generate an open-circuit voltage of 15.9 V. Meanwhile, the influence of some critical parameters such as liquid column length, PTFE tube wall thickness and liquid column motion speed on the output performance of the GD-TENG were systematically investigated. Furthermore, the GD-TENG can successfully harvest mechanical energy to power microelectronic devices. A sensing system was designed based on the GD-TENG device for displacement monitoring of moving objects. This work provides a new research path in the field of mechanical energy harvesting and self-powered displacement monitoring.

Maximizing friction by liquid flow clogging in confinement

In the nanoscale regime, flow behaviors for liquids show qualitative deviations from bulk expectations. In this work, we reveal by molecular dynamics simulations that plug flow down to nanoscale induces molecular friction that leads to a new flow structure due to the molecular clogging of the encaged liquid. This plug-like nanoscale liquid flow shows several features differ from the macroscopic plug flow and Poiseuille flow: It leads to enhanced liquid/solid friction, producing a friction of several order of magnitude larger than that of Couette flow; the friction enhancement is sensitively dependent of the liquid column length and the wettability of the solid substrates; it leads to the local compaction of liquid molecules that may induce solidification phenomenon for a long liquid column.Graphical abstract

An innovative approach for bias correction of a passive controlled offshore structure using experimental non-contact measurements

Abstract The discrepancy between the theoretical and experimental results is defined as one of the main reasons for updating the analytical models of the structures based on experimental data sets. Although various updating methods have been proposed in the literature, the capability of the approaches on controlled systems is yet to be investigated. In this paper, a numerical model updating method is proposed considering both parametric and structural uncertainties on a passive controlled complex structural system. The method is applied on a three-dimensional offshore jacket platform model including an attached Tuned Liquid Column Gas Damper (TLCGD) damping system. The effect of the damper parameters on updating the numerical model is investigated for the first time using a Laser Doppler Vibrometer (LDV) as a non-contact measuring system. The maximum decrement is occurred using a sine function which seems to be because of the sinusoidal nature of the experimental data. According to the results, the discrepancy between the numerical and experimental data can be decreased by 75 percent utilizing non-contact measurements and discrepancy functions. The results also indicate that by calibrating the gas pressure and the total liquid column length of the TLCGD damping system, as the most important parameters of the damper, the discrepancy is decreased almost 66 percent. The proposed method of updating the FE model for the controlled systems is beneficial for the old sophisticated controlled practical systems that increasing their life time span is essential.

Electrical-analogy network model of a modified two-phase thermofluidic oscillator with regenerator for low-grade heat recovery

An electrical-analogy network model including a regenerator model based on wet thermoacoustic principle is proposed to predict the resonant frequency and the onset temperature difference of a modified two-phase thermofluidic oscillator, which is similar to a non-inertive-feedback thermofluidic engine reported in the literature. Besides, a screen-stacked regenerator is introduced to reduce the irreversible loss induced by heat transfer and a gas reservoir is inserted to tune the acoustic field. An electrical capacitance that accounts for the compressibility caused by thermal-relaxation effect and an electrical resistance that accounts for the heat loss due to viscous dissipation are included in the regenerator model, with all other components modeled based on lumped principle. The electrical-analogy network model can well predict the onset temperature difference in both trend and magnitude, with which the deviations from experimental results are only 0.8–5.8% for the present model, while they are 68.5–72.0% for the previous linear temperature profile heat exchanger model. In addition, the calculated and experimental resonant frequencies are also in reasonable agreement, since the present model overestimates the measured resonant frequencies by 1.5–12.5%, while the previous model overestimates by 5.2–16.5%. The effects of the liquid column length inside the load tube, the gas reservoir volume and the working fluid on the resonant frequency and the onset temperature difference are investigated. The results from this work can help to better understand and then optimize a two-phase thermofluidic oscillator.

Numerical Demonstration of In-Tube Liquid-Column Migration Driven by Photoisomerization.

Droplet manipulation by light-induced isomerization was numerically demonstrated and investigated regarding the driving mechanism. Such a non-invasive manipulation of a droplet in a microchannel can be realized, for example, by the use of watery solution of photoresponsive surfactant that exhibits the isomerization. Due to variable fluid properties between the cis and trans isomers, one-side light irradiation on a liquid column in a tube would lead to some kind of imbalance between the two ends of the liquid column and then drive droplet migration. The present numerical simulations of air–liquid two-phase flow and its scalar transport of the isomer, considering the variable static contact angle, agreed quantitatively with the experimental results in terms of the migration speed. This fact supports the contention that the droplet migration is more likely to be driven by an imbalance in the wettability, or the contact angle. The migration speed was found to be less dependent on the liquid-column length, but proportional to the tube diameter.

Experimental studies of water hammer in propellant feed system of reaction control system

Water hammer pressure transient produces large dynamic forces which can damage the pipes and other assemblies in the feed line of a reaction control system (RCS). It has led to the failure of pressure transducers monitoring the manifold pressure in the feed line of RCS. Therefore, water hammer studies have been carried out to understand its effect in feed line. Feedline system has been simplified to develop a mathematical model and experiments have been carried out at extensive levels. The mathematical model was developed considering pipe of uniform c/s and moving liquid-gas interface. The experimental studies have been done using water as working medium instead of actual propellant. The studies showed that rate of pressurization have a very critical role on the water hammer amplitude. Sensitivity studies have been also carried out to study the effect of density, friction and initial liquid column length on water hammer amplitude.

Experiments and Modeling of Air-Powered Needle-Free Liquid Injectors

Liquid jet injectors are biomedical devices used for drug delivery without the use of hypodermic needles. These devices generate a high-speed small-diameter liquid jet of sufficient pressure to penetrate the skin and deliver an appropriate amount of medication. In this study, a detailed investigation on needle-free liquid injection systems powered by compressed air is carried out. Experiments are conducted using a custom-built experimental prototype which makes it possible to vary a number of parameters. The experimental results are used to validate a fluid mechanics model for air-powered needle-free injectors. The modifies a forcing term that relates the air pressure used to drive the injection to the stagnation pressures of the jet exiting the injector. The results are analyzed to determine which parameters among driver pressure, nozzle diameter, liquid column length, and frictional losses most significantly impact the peak and average stagnation pressures of the jet exiting the air-powered needle-free liquid injector.

Acid-sensitive pH sensor using electrolysis and a microfluidic channel for read-out amplification

We demonstrated an acid-sensitive pH sensor based on a novel and simple sensing mechanism. Electrolysis bubbles and a microfluidic channel are used for read-out amplification. The amount of hydrogen bubbles generated through electrolysis varies with the pH levels of a buffer solution. The change in volume with respect to pH levels is measured electrically through sensing electrodes. To maximize the change of the pushed liquid column length for a given bubble volume, a microfluidic channel with small cross-sectional area was fabricated and integrated onto the sensing components. For a stronger acid, the change in current increased with increasing liquid column length and higher liquid conductivity. The interplay of these two effects enhanced sensor output, increasing sensitivity at lower pH levels in our sensor.

A design procedure of two-way liquid dampers for attenuation of wind-induced responses of tall buildings

A new design procedure of a two-way liquid damper which reduces wind-induced responses of a tall building is presented as a quick guide for structural engineers. The two-way liquid damper combines the (1) Tuned Liquid Column Damper (TLCD) in which liquid moves through a U-shape tube and the (2) Tuned Sloshing Damper (TSD) in which liquid sloshes within a container, respectively for two orthogonal directions. Dimensions of the damper, such as horizontal liquid column length and the thickness of the TLCD, the width of the TSD, and liquid height are determined given the condition of tuning the natural frequencies of liquid motion in the damper to those of the building. The design procedure is a trial and error process of satisfying geometrical constraints (i.e., maximum space where the damper is installed) and varying controlled response factors (i.e., performance of vibration attenuation). A design example of the damper is illustrated in the paper for its installation at a 64-story reinforced-concrete residential building.

The Tunable Optofluidics Waveguide Design Based on the Novel Dual Side-Coupled Cavities Plasmonic Structure

We present a tunable wavelength filter in plasmonic metaldielectricmetal (MIM) side-coupled-cavity waveguide with optofluidics pump system proposed to realize tunable mechanism. The peak wavelength can shift by manipulating the length of liquid column and the effective refractive index. The finite difference time domain method is used in the numerically simulated experiment and the resonant wavelengths from 1000 to around 1800nm had been analyzed. The results reveal that the resonant wavelengths are proportional to the liquid volume length and refractive index of liquid in the cavity. This waveguide filter can be used in integrated optical circuits.

Visual detection of lead(ii) using a simple device based on P(NIPAM-co-B18C6Am) hydrogel

A simple and portable device equipped with poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-B18C6Am)) hydrogel is developed for visual detection of Pb2+ ions. The device consisted of a compartment for incorporating the hydrogel, a flow channel and an indicating liquid chamber with colored solution, and a dense and elastic polyethylene (PE) membrane to separate the hydrogel and the colored solution. The device works like a mercury thermometer, in which the P(NIPAM-co-B18C6Am) hydrogel and the PE membrane act as the Pb2+ sensor and actuator and the colored liquid column in the flow channel acts as the indicator. The volume of P(NIPAM-co-B18C6Am) hydrogel changes in response to Pb2+ concentration at a certain temperature due to the formation of B18C6Am/Pb2+ host–guest complexes, and the volume change of the hydrogel causes elastic deformation of the PE diaphragm, which pushes out the colored solution from the liquid chamber into the flow channel to form a liquid column. Therefore, the Pb2+ concentration can be detected quantitatively by simply and easily measuring of the liquid column length. The device shows excellent sensitivity towards Pb2+ ions. The detection performances of the proposed devices are satisfactorily stable and repeatable. This simple and portable device enables visual detection of Pb2+ concentration without the help of electrical amplification or spectroscopic measurements.

Design, construction, and performance of a real-time holographic refractometry prototype for liquid analysis

The development and the performance of a portable holographic refractometer prototype for liquid measurement employing multimode diode lasers with emission centered at 662 nm as light sources is reported. Due to the multiwavelength character of the holographic recording, a synthetic wavelength was generated, and the diffracted wave intensity was thus modulated as a function of the optical path difference between the reference and the object beams. The transparent test cell containing the liquid was placed at the reference-beam arm of the optical setup, while the contour interferogram generated on the holographic image of a flat object was used for fringe counting. A change ΔL on the liquid column length is proportional to the Δp running fringes on the object image, and from this relation the refractive index of the test liquid was obtained. The holograms were recorded on a photorefractive Bi(12)TiO(20) crystal whether using a single multimode diode laser or by combining two diode lasers. In the latter configuration the synthetic wavelength can be varied in order to enhance the measurement sensitivity and∕or to allow the analysis of turbid liquids. The size of the whole prototype is 54 × 22 × 14 cm(3). The refractive indexes of ethanol∕water mixtures with different concentrations were measured, as well as the NaCl concentrations in aqueous solutions were determined upon comparison with an empirical curve. In both cases the results were compared with the ones obtained through an Abbe refractometer.

Spray characteristics of the rotating fuel injection system of a micro-jet engine

In micro-turbojet engines with less than 350 kW power, it is not easy to find a suitable fuel injector with good spray quality. However, the rotating fuel injection system can potentially provide high atomization quality without the high-pressure fuel pump through the centrifugal forces of the engine shaft. With this motivation, a very small rotating fuel injector with 40 mm diameter is designed for the micro-turbo jet engine. It is directly linked to a high-speed rotational spindle capable of a speed up to 100,000 rpm. The droplet size, velocity, and spray distribution from the PDPA (Phase Doppler Particle Analyzer) system are measured. The spray is also visualized by a high-speed camera. The test results show that the length of liquid column from injection orifice is controlled by the rotational speeds and that SMD (Sauter Mean Diameter) is decreased with increasing rotational speeds. At a rotational speed of 73.3 m/s (35,000 rpm), SMD is lower than 60 μm at the entirety of the measuring space in the case of Type 2 (injection orifice diameter of 1.5 mm) and Type 3 (injection orifice diameter of 2.2 mm). Therefore, conceptually, it is possible to apply this small rotating fuel injection system to the micro-turbojet engine combustor.

Wind-induced vibration control of long span cable-stayed bridges using multiple pressurized tuned liquid column dampers

This paper explores the possibility of using multiple pressurized tuned liquid column damper (MPTLCD) to reduce wind-induced vibration of long span cable-stayed bridges. By implementing a static pressure inside two sealed air chambers at two ends of a traditional tuned liquid column damper (TLCD), a pressurized tuned liquid column damper (PTLCD) is formed and its natural frequency can be adjusted by not only the length of its liquid column but also the pressure inside its two air chambers. This special feature of PTLCD in frequency tuning greatly facilitates its application to long span cable-stayed bridges for mitigating wind-induced multi-modes of vibration. To further enhance the robustness and effectiveness of PTLCD for vibration control, MPTLCDs are explored in this study. The finite element model of MPTLCD is developed and incorporated into the finite element model of a long span cable-stayed bridge for predicting the buffeting response of the coupled MPTLCD–bridge system in the time domain. The performance of MPTLCD for suppressing combined lateral and torsional vibration of a real long span cable stayed bridge is numerically assessed. The investigations show that the MPTLCD not only provides great flexibility for selecting liquid column length but also significantly reduces the lateral and torsional displacement responses of the long span bridge under wind excitation.

Buffeting response control of a long span cable-stayed bridge during construction using semi-active tuned liquid column dampers

The frequency of a traditional tuned liquid column damper (TLCD) depends solely on the length of liquid column, which imposes certain restrictions on its application to long span cable-stayed bridges during construction. The configuration of a cable-stayed bridge varies from different construction stages and so do its natural frequencies. It is thus difficult to apply TLCD with a fixed configuration to the bridge during construction or it is not economical to design a series of TLCD with different liquid lengths to suit for various construction stages. Semi-active tuned liquid column damper (SATLCD) with adaptive frequency tuning capacity is studied in this paper for buffeting response control of a long span cable-stayed bridge during construction. The frequency of SATLCD can be adjusted by active control of air pressures inside the air chamber at the two ends of the container. The performance of SATLCD for suppressing combined lateral and torsional vibration of a real long span cable-stayed bridge during construction stage is numerically investigated using a finite element-based approach. The finite element model of SATLCD is also developed and incorporated into the finite element model of the bridge for predicting buffeting response of the coupled SATLCD-bridge system in the time domain. The investigations show that with a fixed container configuration, the SATLCD with adaptive frequency tuning can effectively reduce buffeting response of the bridge during various construction stages.

Tuned liquid column dampers with adaptive tuning capacity for structural vibration control

The natural frequencies of a long span bridge vary during its construction and it is thus difficult to apply traditional tuned liquid column dampers (TLCD) with a fixed configuration to reduce bridge vibration. The restriction of TLCD imposed by frequency tuning requirement also make it difficult to be applied to structure with either very low or high natural frequency. A semi-active tuned liquid column damper (SATLCD), whose natural frequency can be altered by active control of liquid column pressure, is studied in this paper. The principle of SATLCD with adaptive tuning capacity is first introduced. The analytical models are then developed for lateral vibration of a structure with SATLCD and torsional vibration of a structure with SATLCD, respectively, under either harmonic or white noise excitation. The non-linear damping property of SATLCD is linearized by an equivalent linearization technique. Extensive parametric studies are finally carried out in the frequency domain to find the beneficial parameters by which the maximum vibration reduction can be achieved. The key parameters investigated include the distance from the centre line of SATLCD to the rotational axis of a structure, the ratio of horizontal length to the total length of liquid column, head loss coefficient, and frequency offset ratio. The investigations demonstrate that SATLCD can provide a greater flexibility for its application in practice and achieve a high degree of vibration reduction. The sensitivity of SATLCD to the frequency offset between the damper and structure can be improved by adapting its frequency precisely to the measured structural frequency.

Multiple tuned liquid column dampers for reducing coupled lateral and torsional vibration of structures

This paper presents a theoretical investigation on the performance of multiple tuned liquid column dampers (MTLCD) for mitigating the coupled lateral and torsional vibration of a long span bridge which can be modelled as a two degrees-of-freedom structure. The cross section of the bridge has a vertical axis of symmetry but with the vertical offset between the elastic centre and the mass centre of the bridge. The external dynamic force and moment are applied at the elastic centre of the bridge. The proposed MTLCD consists of two sets of liquid column dampers with one tuned to the lateral frequency of the bridge and the other tuned to the torsional frequency of the bridge. The equations of motion for the coupled lateral and torsional vibration of the bridge with MTLCD are first presented. The nonlinear damping property of MTLCD is linearized using the equivalent linearisation technique. Extensive parametric studies are then carried out in the frequency domain to find beneficial parameters of the MTLCD for achieving maximum reduction of coupled lateral and torsional vibration of the bridge. The parameters investigated herein include water mass distribution between the two dampers, distance from the centre line of the MTLCD to the rotational axis of the bridge, ratio of horizontal length to total length of liquid column, head loss coefficient, and frequency tuning ratio. The performance of the MTLCD in reducing buffeting response of the bridge due to turbulent wind is finally investigated. This study shows that the performance of MTLCD in reducing the lateral and torsional displacements of the bridge depends on the head-loss coefficient and the frequency-tuning ratio significantly. It is also demonstrated that the aeroelastic effects due to the interaction between turbulent wind and bridge motion is a crucial factor affecting the performance of MTLCD in reducing buffeting responses of the bridge.

New type of glucose sensor based on enzymatic conversion of gel volume into liquid column length.

A way to convert the volume change of a biochemo-mechanical gel into the change in liquid column length was developed. Our trial sensor device consisted of a small compartment for incorporating the gel, a flow channel with a filled dye solution, and a poly(dimethylsiloxane) (PDMS) diaphragm by which the gel and the dye solution were separated. A lightly cross-linked N-isopropylacrylamide (NIPAAm)/acrylic acid (AA) copolymer gel with immobilized glucose oxidase was used as a sensing element. It was found that a change in the gel volume caused by the immobilized enzyme reaction was accurately converted into a change of the column length (Deltal) with the help of the PDMS diaphragm. By use of a cylindrical gel (diameter approximately 2 and thickness approximately 1 mm), the time curve of Deltal varied depending upon glucose concentration over a range of 0.2-50 mM; in particular, it is of importance that semilogarithmic plots of Deltal (in mm) against glucose concentration (in mM) can be used as a calibration curve. For glucose solutions of mM order, 1 min was enough to determine the concentrations, whereas 10 min was required for concentrations of microM order. When the measurement time was limited within 10 min, the lower detection limit was 200 microM. The response was affected by buffering capacity of the samples, but this was controllable through reduction of the sample volume. These results indicate that the present way can be used for the determination of glucose concentration.

Multiple‐tuned liquid column dampers for torsional vibration control of structures: theoretical investigation

AbstractThis paper presents a theoretical investigation on the performance of multiple‐tuned liquid column dampers (MTLCD) for reducing torsional vibration of structures in comparison with single‐tuned liquid column dampers (STLCD). The analytical model is first developed for torsional vibration of a structure with an MTLCD under either harmonic excitation or white noise excitation. The experimental results are then used to verify the analytical model for coupled MTLCD‐structure systems under harmonic excitation. The performance of an MTLCD and its beneficial parameters for achieving the maximum torsional response reduction to white noise excitation are finally investigated through an extensive parametric study in terms of the distance from the centre line of the MTLCD to the rotational axis of the structure, the ratio of the horizontal length to the total length of liquid column, frequency bandwidth, head‐loss coefficient, the number of TLCD units in an MTLCD, frequency‐turning ratio and the spectral level of excitation moment. The results show that there is an optimal head‐loss coefficient and an optimal frequency bandwidth for an MTLCD to achieve the maximum torsional response reduction. It is also demonstrated that the sensitivity of an optimized MTLCD to the frequency‐tuning ratio is less than that of an optimized STLCD, and it can be further improved by increasing the bandwidth but at the cost of less torsional vibration reduction. Copyright © 2002 John Wiley & Sons, Ltd.

2204 噴射液体に粒子を混入した場合の模擬ディーゼルノズル噴孔内キャビテーションと微粒化

Water with or without tracer particles was ejected to still atmospheric air from sharp edge type 2-dimensional nozzle in order to clarify the effects of the particles on cavitating flow of nozzle hole and liquid jet atomization. Characteristics of liquid jet atomization were evaluated by means of the electrical resistance method to measure the breakup length of the liquid column. The needle type electric probes, were mounted in the nozzle hole, was used to detect the local and temporal data of cavitating bubbles. The breakup length of liquid column is hardly affected by tracer particles, while cavitating bubbles in the nozzle hole are influenced.