Kinematic Viscosity Of Liquid Research Articles

ORIFICE WALL CAVITATION AND SINGLE STRING CAVITATION IN FUEL INJECTORS

It has been pointed out that cavitation inside a fuel injector plays an important role in the fuel spray characteristics, which affects the thermal efficiency and exhaust gas emissions. Recently, it was pointed out that when needle lift is low, not only orifice wall cavitation but also single string cav-itation may occur in the mini-sac and valve-covered orifice (VCO) nozzles, which increases largely the spray cone angle. However, the mechanism and condition of the appearance of single string cav-itation have not been clarified yet. In this study we carry out high-speed visualization of orifice wall cavitation and single string cavitation in various transparent injectors with a single orifice and a simple rectangular sac, whose gap <i>Z</i>, sac width <i>W</i>, orifice diameter <i>D</i>, liquid kinematic viscosity ν, and mean liquid velocity <i>V</i> in the orifice are varied, to investigate the governing dimensionless parameters and to examine whether we can quantitatively predict the formation criteria of single string cavitation or not. Moreover, particle image velocimetry (PIV) analysis is conducted to measure the velocity distribution, to clarify the flow structure, and to quantify the circulation in the sac. As a result, we conclude that regardless of the shape and size of the fuel injectors, the length of cavitation in an orifice can be predicted by using the modified cavitation number σ<sub>c</sub>. The appearance of single string cavitation and circulation in the sac are possible to be predicted quantitatively by using a dimensionless Re<sub>1</sub> proposed in this study, which is the ratio among the inertial and viscous forces.

Computing the viscous effect in early-time drop impact dynamics

The impact of a liquid drop on a solid surface involves many intertwined physical effects, and is influenced by drop velocity, surface tension, ambient pressure and liquid viscosity, among others. Experiments by Kolinski et al. (Phys. Rev. Lett., vol. 112, no. 13, 2014b, p. 134501) show that the liquid–air interface begins to deviate away from the solid surface even before contact. They found that the lift-off of the interface starts at a critical time that scales with the square root of the kinematic viscosity of the liquid. To understand this, we study the approach of a liquid drop towards a solid surface in the presence of an intervening gas layer. We take a numerical approach to solve the Navier–Stokes equations for the liquid, coupled to the compressible lubrication equations for the gas, in two dimensions. With this approach, we recover the experimentally captured early time effect of liquid viscosity on the drop impact, but our results show that lift-off time and liquid kinematic viscosity have a more complex dependence than the square-root scaling relationship. We also predict the effect of interfacial tension at the liquid–gas interface on the drop impact, showing that it mediates the lift-off behaviour.

Experimental investigation of saturated liquid kinematic viscosity and surface tension of two isomeric refrigerants trans-1,1,1,4,4,4-hexafluoro-butene (R1336mzz(E)) and cis-1,1,1,4,4,4-hexafluoro-butene (R1336mzz(Z)) by surface light scattering

In the present work, the liquid kinematic viscosity and surface tension of two low-GWP (Global Warming Potential) refrigerants as potential working fluids in heat pump, refrigeration, and organic Rankine cycles were investigated under saturation conditions by surface light scattering in the temperature range from (303.15 K to Tc). With the experimental data, a van der Waals type equation, and a polynomial equation with an additional term were proposed to correlate the surface tension and viscosity data, respectively.

Optimization of Tuned Liquid Damper Including Different Liquids for Lateral Displacement Control of Single and Multi-Story Structures

This study focuses on tuned liquid dampers (TLDs) using liquids with different characteristics optimized with the adaptive harmony search algorithm (AHS). TLDs utilize the characteristic features of the liquid to absorb the dynamic forces entering the structure and benefit from the sloshing movement and the spring stiffness created by the liquid mass. TLDs have been optimized to investigate the effect of liquid characteristics on the control by analyzing various liquids. For optimization, the memory consideration ratio (HMCR) and fret width (FW) values were adapted from the classical harmony search (HS) algorithm parameters. The TLDs were used on three types of structure models, such as single-story, 10, and 40 stories. The contribution of the liquid characteristics to the damping performance was investigated by optimizing the minimum displacement under seismic excitation. According to the results, it was understood that the liquid density and kinematic viscosity do not affect single-story structures alone. However, two characteristic features should be evaluated together. As the structure mass increases, the viscosity and density become more prominent.

The history of creation and modernization of the state primary standards of units of dynamic, kinematic viscosity of liquid and density

The history of creation and modernization of the state primary standards of units of dynamic, kinematic viscosity of liquid and density

Saturated liquid kinematic viscosity, surface tension and thermal diffusivity of two low-GWP refrigerants 3,3,3-trifluoropropene (R1243zf) and trans-1-chloro-3,3,3-trifluoro-1-propene (R1233zd(E)) by light scattering method

To facilitate the application of low-GWP refrigerants in the refrigeration and heat pump systems, it is highly necessary to obtain their thermophysical properties including the liquid surface tension, viscosity and thermal diffusivity. In the present study, these thermophysical properties of two low-GWP refrigerants 3,3,3-trifluoropropene (R1243zf) and trans-1-chloro-3,3,3-trifluoro-1-propene (R1233zd(E)) were investigated by using the light scattering method under saturation conditions. With the experimental data, a van der Waals type equation for surface tension and polynomial equation with an additional term to capture the trend close to the critical point for viscosity and thermal diffusivity were proposed for the future applications.

Thermophysical Properties of the Binary Mixtures of Iso-octane with Methyl Hexanoate, n-Decane with Methyl Decanoate and Methyl Octanoate: Experimental Investigation and Molecular Dynamic Simulation

For the description of the physical properties of complex fuel, fuel surrogates and their thermophysical properties are crucial to be proposed and determined. The thermophysical properties of fuel are in connection with the design and optimization of injection system in engine, and furtherly influence the performance as well as the emissions of the engine. In this study, we investigated the liquid kinematic viscosity and surface tension of the proposed binary fuel surrogates containing iso-octane with methyl hexanoate between (303.15 and 408.15) K, n-decane with methyl decanoate and methyl octanoate between (313.15 and 423.15) K at the three-mole fraction (0.2500, 0.5000, and 0.7500) close to saturation conditions, respectively, by surface light scattering method. A U-tube densimeter was utilized to determine their liquid density from (293.15 to 433.15) K. Additionally, the GROMOS force field which has been validated for similar systems in our previous study was also applied to simulate the thermophysical properties of the proposed mixtures over the same temperature range. The results show good agreement between the experimental data and the simulation, which provides more demonstration of the acceptance of the GROMOS force field for simulating the alkanes and fatty acid methyl and ethyl esters.

Experimental investigation and molecular dynamic simulation of thermophysical properties of biodiesel surrogates: The binary mixtures of n-hexadecane with ethyl hexanoate and ethyl heptanoate

The thermophysical properties of biodiesel surrogates are of great importance for the development of the new and clean fuel substitutes or additives. Experimental investigation and molecular dynamic simulation of the related thermophysical properties such as the liquid density, kinematic viscosity and surface tension over a sufficient wide temperature range will facilitate the corresponding researches of selecting the proper fuel surrogates and designing the spray system of the internal combustion engine. Therefore, the present study investigated liquid surface tension and kinematic viscosity of the proposed physical biodiesel surrogates of n-hexadecane with ethyl hexanoate and ethyl heptanoate by the surface light scattering method at three mole fractions (0.25, 0.50 and 0.75) over the temperature range from (353.15 to 433.15) K. Additionally, the liquid density was also determined by a U-tube densimeter in the temperature range between (293.15 and 433.15) K. Meanwhile, three force fields including OPLS-AA, GROMOS and AMBER were selected and validated with n-hexadecane and ethyl heptanoate in a wide temperature range and the GROMOS force field was demonstrated to be the best one for the description of the three thermophysical properties of the two fluids. A further molecular dynamic simulation with GROMOS force field was applied to the proposed binary surrogates of n-hexadecane with ethyl hexanoate and ethyl heptanoate, and the results for the three properties agreed well with their experimental values over the entire temperature range.

Simulation study on liquid percolation in diffusion layer of in-vitro diagnostic chips

In-vitro diagnostic chips were used to achieve point-of-care testing for its advantages including rapidity, convenience, and accuracy. Diffusion layer in multi-layer structure of in-vitro diagnostic chips integrate multiple functions, including even dispersion of the liquid and high reflectivity. However, few studies of liquid percolation in the diffusion layer have been reported. In this paper, Lattice Boltzmann Method was used to simulate the process of liquid percolation in diffusion layer of in-vitro diagnostic chips. Effects of microsphere material, microsphere diameter, and liquid type (serum or water) on percolation were investigated. The results showed that all the 3 factors had increasing degree of influence on liquid percolation in diffusion layer. Based on these simulations, it was found that a particle diameter of 4 ∼ 6 μm, liquid kinematic viscosity of 0.89 × 10−6∼1.37 × 10−6 m2/s, and microsphere contact angle of 30.5 ∼ 40.5° were conducive to controlling the percolation process in chip diffusion layer. Thus, Lattice Boltzmann Method can be nominated to explore the percolation laws in diffusion layer of in-vitro diagnostic chips. Further simulation studies should provide the basic data required for the development of multi-layer in-vitro diagnostic chips, which helps chip designers to select appropriate materials and particle diameter.

Experimental investigation and correlations of thermophysical properties for bio-aviation kerosene surrogate containing n-decane with ethyl decanoate and ethyl dodecanoate

Physical fuel surrogate is always necessary to be proposed to match physical properties such as liquid density, viscosity and surface tension of the real bio-aviation kerosene for the characteristics of their spray performance. Thus, it is crucial to determine the related thermophysical properties over a wide temperature range for a further development of the fuel spray system. Therefore, binary surrogates of n-decane with ethyl decanoate and ethyl dodecanoate were proposed and their thermophysical properties were investigated in the present work. The liquid density was obtained using a U-tube densimeter in the temperature range between (293.15 and 433.15) K. The liquid kinematic viscosity and surface tension were investigated simultaneously by surface light scattering (SLS) method in the temperature range from (313 to 423) K. Additionally, the refractive index was measured by a refractometer in the temperature range from (278.15 to 358.15) K. Furthermore, correlations for these properties were developed as the function of mole fraction and temperature. The relative deviations of experimental liquid density, kinematic viscosity, surface tension and refractive index from those calculated according to the correlations were within the range of ±0.2%, ±2%, ±1% and ±0.08%, respectively.

Empirical correlation for spray half cone angle in plain-jet airblast atomizers

Plain-jet airblast atomizers are widely used in industrial applications. The literature contains numerous papers on Sauter mean diameter, however, there is no estimation method available for spray cone angle, SCA, which derivation is the primary goal of this study. Four distinct, practical model liquids were analyzed: distilled water, diesel oil, light heating oil, and crude rapeseed oil. The atomizing pressure and liquid preheating temperature were varied in the range of 0.3–2.4 bar and 25–85 °C, respectively. This latter parameter enabled a wide and continuous liquid kinematic viscosity investigation range of 0.33–44.2 mm2/s. The resulting sprays were imaged at various shutter speeds for proper edge detection. An adaptive thresholding algorithm was developed in Matlab software environment to calculate SCA. The methodology is discussed in detail to facilitate the re-implementation of this technique since there is no generally accepted method for SCA measurement. SCA inversely varied with liquid density and followed a power law with the air-to-liquid mass flow ratio; however, the derived expression also performed well by replacing air-to-liquid mass flow ratio by either Mach number or momentum flux ratio. A simple empirical equation was derived, which allows the estimation of SCA of airblast atomization in a wide parameter range within a 3.5% deviation. The measured results were evaluated in the light of high-speed camera images in the vicinity of the nozzle; it was found that increased liquid jet breakup length decreases SCA while intense ligament formation increases it.

Thermal transport characteristics of AC electrokinetic flow in a micro-annulus

Alternating current electroosmotic flow and associated heat transfer under constant surface heat flux conditions are numerically examined in a micro-annular channel. The channel surfaces are arbitrarily heated and/or cooled, while the resultant heating is normally transferred downstream by the advection mechanism. An important feature of time-periodic electrokinetic flow is that there is not any preferential axial direction. If the excitation frequency is sufficiently small and/or the liquid kinematic viscosity is sufficiently large, momentum diffuses far into the bulk fluid and thus the advection mechanism is intensified. The reverse is true for relatively large frequency and small kinematic viscosity values. Mean Nusselt number fluctuates over a period of time; its time-averaged magnitude is dependent on the electrokinetic diameter and the dimensionless frequency. This quantity approaches a specific value regardless of the thermal scale and the wall heat flux ratios. The system may attain optimal effectiveness for particular magnitudes of the frequency and electrokinetic diameter. An interesting case may exist in the cooling mode where the axial variation of the mean fluid temperature vanishes temporarily while the state of constant surface temperature is instantly satisfied; at the particular points in time, the advection mechanism does not contribute to the development of the liquid temperature field.

Comparative visualized investigation of impact-driven high-speed liquid jets injected in submerged water and in ambient air

This paper is a comparative study on the characteristics of high-speed liquid jets injected in surrounding water and air using shadowgraph technique. One of the main objectives is to investigate the effects of liquid’s physical properties, used to generate the high-speed liquid jets, on jet generation’s characteristics. Moreover, comparative investigations on effects of those liquid jets after injected in water and air are reported. The high-speed liquid jets were generated by the impact of a projectile launched by a horizontal single-stage power gun. The impact-driven high-speed liquid jets were visualized by shadowgraph technique and images were recorded by a high-speed digital video camera. The process of impact-driven high-speed liquid jet injection in air and water, oblique shock waves, jet-induced shock waves, shock waves propagation, the bubble behavior, bubble collapse-induced rebound shock waves and bubble cloud regeneration were clearly observed. It was found that different properties of liquid (surface tension and kinematic viscosity) affect the jet maximum velocity and shape of the jet. Bubble behaviors were only found for the jet injected in water. From the shadowgraph images, it is found that the maximum average jet velocity, expansion and contraction velocities of bubble in axial direction increase when the value of the multiplied result of surface tension by kinematic viscosity increases. Therefore, surface tension and kinematic viscosity are the significant physical properties that affect characteristics of high-speed liquid jets.

Chezy’s resistance coefficient in a horseshoe-shaped tunnel

The calculation of Chezy’s resistance coefficient (CRC) is typically not provided a priori in a design problem, and its value is often selected subjectively from the literature in most open channels and conduits for the uniform flow. The evaluation of this coefficient is crucial to channel design and for computing its normal depth. The primary purpose of this research study is to revisit the mathematical formulation for the resistance coefficient. A general explicit relation of the resistance coefficient in turbulent flow is set with different geometric profiles of conduits and channels, mainly the horseshoe-shaped tunnel using the rough model method (RMM). CRC is firmly based on the internal walls' absolute roughness of the channel, the liquid kinematic viscosity, the longitudinal slope, the discharge and the filling rate. Additionally, a simplified method is proposed to determine CRC with a restricted number of variables such as the kinematic viscosity, the absolute roughness, the slope of the conduit, and the discharge. Based on studying the variation of CRC as a function of the filling rate, another explicit expression is provided to compute this coefficient efficiently when its maximum value is reached. To demonstrate how Chezy’s resistance coefficient can be calculated in a horseshoe-shaped tunnel, some examples of calculations are proposed.

Liquid surface tension, kinematic viscosity, density and refractive index of the binary mixtures of n-hexadecane with methyl butyrate and methyl decanoate close to saturation conditions

To facilitate the application of clean alternative fuels or fuel additives in compression ignition engines and a better understanding of the characteristics of their combustion and emission, physical biofuel surrogates are necessary to be proposed in computation and the knowledge of their thermophysical properties, such as liquid density, surface tension and viscosity, are also crucial for the design and optimization of the fuel injection system. Therefore, the surface light scattering (SLS) method was adopted for the simultaneous determination of the liquid surface tension and kinematic viscosity of the binary mixtures containing n-hexadecane, methyl butyrate and methyl decanoate in the temperature range between (353.15 and 423.15) K in the present work. Additionally, a U-tube densimeter and refractometer were used to obtain the liquid density and refractive index of the binary mixtures in the temperature range from (293.15–423.15) K and (293.15–358.15) K, respectively. Correlations for all thermophysical properties against temperature and mole fraction were also proposed. The relative deviations of liquid density, refractive index, kinematic viscosity as well as surface tension data from those calculated by the proposed equations were within ±0.3%, ±0.20%, ±2% and ±1%, respectively for the binary systems.

Experimental Investigation of the Thermophysical Properties of the Bio-Aviation Fuel Surrogates: Binary and Ternary Mixtures of n-Dodecane, Methyl Butyrate, and Methyl Decanoate

For the investigation of injection characteristics of fuels in the internal combustion engines or turbines, thermophysical properties like liquid kinematic viscosity, surface tension, density, and refractive index are crucial and necessary. In this work, the liquid kinematic viscosity and surface tension were measured by surface light scattering (SLS) for the binary and ternary mixtures of n-dodecane with methyl butyrate and methyl decanoate, respectively, in the temperature ranges from (308.15 to 413.15) K for the mixtures and (298.15 to 423.15) K for methyl butyrate. Additionally, the liquid density was determined by a U-tube densimeter from (293.15 to 423.15) K, and refractive index was measured from (278.15 and 358.15) K. Furthermore, the experimental data of surface tension and kinematic viscosity for the mixtures were correlated with two proposed equations against the temperatures and mole fractions. The density and refractive index data were correlated by polynomial functions. This work provides essential data and correlation models for the crucial thermophysical properties of the binary model fuels for the bio-aviation kerosene in connection with the investigation of the fuel injection and combustion system.

Experiment and correlation of the thermophysical properties for binary and ternary liquid mixtures of three fatty acid ethyl esters and n-dodecane

In present study, surface light scattering (SLS) was used for the simultaneous determination of liquid surface tension and kinematic viscosity of the binary and ternary mixtures of three fatty acid ethyl esters (FAEEs) and n-dodecane. The SLS apparatus was firstly checked with n-dodecane and a good agreement between our data and those from literatures could be found. By utilizing this apparatus, both properties were investigated in the temperature ranges between (308 and 413) K. Additionally, the liquid density and refractive index were determined by a densimeter between (293 and 423) K and a refractometer from (278 to 358) K, respectively. The thermophysical property data obtained in this study were correlated as polynomial equations of temperature and mole fraction of the pure components. This work provided the crucial thermophysical properties and the corresponding models in connection with the application in the design and optimization of the injection system of internal combustion engine (ICE).

Thermophysical properties of fatty acid methyl and ethyl esters

In present study, surface light scattering (SLS) was used for the simultaneous determination of liquid surface tension and kinematic viscosity of twelve fatty acid esters, including six methyl esters (FAMEs) and six ethyl esters (FAEEs). The SLS apparatus was firstly checked with a reference fluid n-dodecane, and a good agreement of our data from SLS with those from literatures could be found. By utilizing this apparatus, both properties were investigated in the temperature ranges between (298 and 448) K for all substances with an exception of methyl myristate and ethyl myristate covering the temperatures between (323 and 448) K due to their high melting points. Additionally, the liquid density and refractive index were determined by an Anton Paar U-tube densimeter between (293 and 453) K and a refractometer from (278 to 358) K, respectively. The surface tension and viscosity data obtained from the SLS experiment were fitted to the van der Waals type and the reciprocal temperature-dependent polynomial equations, respectively. The quadric and linear functions were adopted to correlate the density and refractive index data, respectively. This work improves the data situation for these fatty acid esters especially at elevated temperatures and provides necessary data and models for the crucial thermophysical properties in connection with the design and optimization of the injection system of an internal combustion engine (ICE).

An Alternative High-Density Ratio Pseudo-potential Lattice Boltzmann Model with Surface Tension Adjustment Capability

In this paper, an alternative model is presented to simultaneously achieve thermodynamic consistency, leading to high-density ratios, and surface tension adjustment capability based on the pseudo-potential lattice Boltzmann model (LBM). These features are achieved by adding two relatively simple terms, each with an adjustable coefficient, selected from the Taylor expansion of the original interaction force, one for achieving and maintaining thermodynamic consistency, and the other for adjusting the surface tension independent of the density ratio. The model also takes advantage of being independent of using SRT, MRT, 2D or 3D lattice models. The capability of the model is evaluated and verified by performing several static and dynamic benchmark test cases. First, the coexistence densities extracted for a flat interface from the model are compared with those of the Maxwell equal area rule in a wide temperature range. Results show that the thermodynamic consistency is well achieved and the coexistence densities are independent of the surface tension strength as well. Next, the well-known Laplace law for a droplet is evaluated and satisfied with the model. In addition, a wide range of surface tension values is achievable at a fixed temperature by adjusting the surface tension adjustment coefficient. After that, the ellipsoidal droplet oscillation is simulated with a good agreement between the analytical and numerical results for the oscillation period. The spurious velocities around the droplet are then evaluated and shown to be reasonable, and comparatively low even at a relatively high-density ratio around of 2400. It was found that the magnitude of these velocities can be further reduced, especially at high-density ratios, by reducing the liquid to gas dynamic viscosity ratio or equivalently increasing the gas to liquid kinematic viscosity ratio. Next, the stability, and the fascinating phenomenon of symmetric bifurcation of a rotating planar droplet are simulated and formation of two- and four-lobed shapes along with rigid rotation is presented depending on the value of the surface tension. Finally, the droplet impact on a liquid film is simulated at a relatively high-density ratio around of 720, and Reynolds number of 1440. However, the upper limit of physical parameters for simulating this phenomenon is found to be a density ratio of 720 and Re and We numbers of 6600 and 275, respectively. Effects of the surface tension strength are shown as well. The crown spread radius from the model agrees well with the analytical solution reported in the literature.

Moving Particle Semi-implicit (MPS) Utilization in Analyzing the Stratification Behavior of Immiscible Liquid

The reactor core accident, especially the reactor core melt-down, is one of the most important things to be considered in analyzing the reactor safety factor. In melted reactor core case, one of the interesting phenomena which can be examined is the process of stratification of a metallic liquid component of the melted reactor core. In this study, it is observed the stratification process of immiscible liquid through simulation and validation with experiment. One method that can be utilized to model the liquid stratification is the MPS (Moving Particle Semi-Implicit) method. The stratification experiments were conducted using water and several kinds of oils. From the gained results, it can be seen that the obtained results of the simulation are in good agreement with the experiment results. In addition, from the simulation and experimental results, it can be seen that the density of liquid significantly affects the stratification process. The kinematic viscosity of liquid also affects the rate of liquid penetration in achieving stratification conditions. Therefore, the MPS method used in this simulation has a good enough capability to simulate the liquid stratification phenomena, which can be implemented in conditions of the melted reactor core prototype.