scholarly journals Alternative Geometric Arrangements of the Nozzle Outlet Orifice for Liquid Micro-Jet Focusing in Gas Dynamic Virtual Nozzles

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1572
Author(s):  
Božidar Šarler ◽  
Rizwan Zahoor ◽  
Saša Bajt
Keyword(s):  
Moving Boundary ◽  
Nozzle Geometry ◽  
Nozzle Outlet ◽  
Two Phase ◽  
Nozzle Orifice ◽  
Gas Dynamic ◽  
Liquid Phases ◽  
Constant Diameter ◽  
Geometric Arrangements ◽  
Outlet Orifice

Liquid micro-jets are crucial for sample delivery of protein crystals and other macromolecular samples in serial femtosecond crystallography. When combined with MHz repetition rate sources, such as the European X-ray free-electron laser (EuXFEL) facility, it is important that the diffraction patterns are collected before the samples are damaged. This requires extremely thin and very fast jets. In this paper we first explore numerically the influence of different nozzle orifice designs on jet parameters and finally compare our simulations with the experimental data obtained for one particular design. A gas dynamic virtual nozzle (GDVN) model, based on a mixture formulation of Newtonian, compressible, two-phase flow, is numerically solved with the finite volume method and volume of fluid approach to deal with the moving boundary between the gas and liquid phases. The goal is to maximize the jet velocity and its length while minimizing the jet thickness. The design studies incorporate differently shaped nozzle orifices, including an elongated orifice with a constant diameter and an orifice with a diverging angle. These are extensions of the nozzle geometry we investigated in our previous studies. Based on these simulations it is concluded that the extension of the constant diameter channel makes a negligible contribution to the jet’s length and its velocity. A change in the angle of the nozzle outlet orifice, however, has a significant effect on jet parameters. We find these kinds of simulation extremely useful for testing and optimizing novel nozzle designs.

Behaviour of air injection nozzles in dissolved air flotation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 25-35 ◽  
Author(s):  
E. M. Rykaart ◽  
J. Haarhoff
Keyword(s):  
Bubble Coalescence ◽  
Second Phase ◽  
Initial Growth ◽  
Two Phase ◽  
Dissolved Air Flotation ◽  
Nozzle Orifice ◽  
Pressure Release ◽  
Air Volume ◽  
Air Flotation ◽  
Dissolved Air

A simple two-phase conceptual model is postulated to explain the initial growth of microbubbles after pressure release in dissolved air flotation. During the first phase bubbles merely expand from existing nucleation centres as air precipitates from solution, without bubble coalescence. This phase ends when all excess air is transferred to the gas phase. During the second phase, the total air volume remains the same, but bubbles continue to grow due to bubble coalescence. This model is used to explain the results from experiments where three different nozzle variations were tested, namely a nozzle with an impinging surface immediately outside the nozzle orifice, a nozzle with a bend in the nozzle channel, and a nozzle with a tapering outlet immediately outside the nozzle orifice. From these experiments, it is inferred that the first phase of bubble growth is completed at approximately 1.7 ms after the start of pressure release.

scholarly journals Variation principle in calculating the flow of a two-phase mixture in the pipes of the cooling systems in high-rise buildings

2018 ◽  
Vol 33 ◽  
pp. 02063 ◽  
Author(s):  
Andrey Aksenov ◽  
Anna Malysheva
Keyword(s):  
Channel Cross Section ◽  
Variation Principle ◽  
Two Phase ◽  
Liquid Phases ◽  
Rate Of Increase ◽  
Annular Layer ◽  
Gas Liquid Flow ◽  
The Stability ◽  
Air Conditioning Systems ◽  
Physical Laws

The analytical solution of one of the urgent problems of modern hydromechanics and heat engineering about the distribution of gas and liquid phases along the channel cross-section, the thickness of the annular layer and their connection with the mass content of the gas phase in the gas-liquid flow is given in the paper.The analytical method is based on the fundamental laws of theoretical mechanics and thermophysics on the minimum of energy dissipation and the minimum rate of increase in the system entropy, which determine the stability of stationary states and processes. Obtained dependencies disclose the physical laws of the motion of two-phase media and can be used in hydraulic calculations during the design and operation of refrigeration and air conditioning systems.

On the Coherent Length of Fluid Nozzles in Grinding

2009 ◽  
Vol 404 ◽  
pp. 61-67 ◽  
Author(s):  
Michael N. Morgan ◽  
V. Baines-Jones
Keyword(s):  
Contact Zone ◽  
Fluid Velocity ◽  
Measured Data ◽  
Nozzle Geometry ◽  
Nozzle Orifice ◽  
Fluid Supply ◽  
Wide Range ◽  
Adequate Coverage ◽  
Nozzle Flows ◽  
Insight Into

The delivery of grinding fluid to the contact zone is generally achieved via a nozzle. The nozzle geometry influences the fluid velocity and flow pattern on exit from the nozzle orifice. It is important to the efficiency of the process and to the performance of the operation that the fluid is delivered in a manner that ensures the desired jet velocity has adequate coverage of the contact zone. Often, assumptions about adequate coverage are based on visual inspections of the jet coherence. This paper provides new insight into the internal nozzle flows and the coherent length of a wide range of nozzle designs. The work presents a new analytical model to predict coherent length which is shown to correlate well with measured data from experiment. Recommendations are given to guide a user to optimal design of nozzles to ensure adequate fluid supply to the contact zone.

Predicting Compositional Two-Phase Flow Behavior in Pipelines

1986 ◽  
Vol 108 (3) ◽  
pp. 207-210 ◽  
Author(s):  
H. Furukawa ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Mass Transfer ◽  
Computational Algorithm ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Phase Flow ◽  
Temperature Profiles ◽  
Balance Equations ◽  
Two Phase ◽  
Liquid Phases ◽  
Retrograde Condensation

A computational algorithm for predicting pressure and temperature profiles for compositional two-phase flow in pipelines has been developed. The algorithm is based on the coupling of the momentum and energy balance equations and the phase behavior of the flowing fluids. Mass transfer between the gas and the liquid phases is treated rigorously through flash calculations, making the algorithm capable of handling retrograde condensation. Temperatures can be predicted by applying the enthalpy balance equation iteratively. However, it was found that the explicit Coutler and Bardon analytical solution for the temperature profile yields nearly identical results for horizontal and near horizontal flow.

Experimental Characterization of Oil-Refrigerant Two-Phase Flow

2000 ◽  
Author(s):  
V. T. Lacerda ◽  
A. T. Prata ◽  
F. Fagotti
Keyword(s):  
Flow Visualization ◽  
Two Phase Flow ◽  
Working Fluid ◽  
Phase Flow ◽  
Oil Viscosity ◽  
Two Phase ◽  
Mixture Flow ◽  
Horizontal Tubes ◽  
Constant Diameter ◽  
Oil Flow

Abstract Several phenomena occurring inside refrigerating systems depend on the interaction between the refrigeration oil and the refrigerant working fluid. Regarding the refrigeration cycle, good miscibility of oil and refrigerant assure easy return of circulating oil to the compressor through the reduction of the oil viscosity. Inside the compressor the lubricant is mainly used for leakage sealing, cooling of hot elements and lubrication of sliding parts. In the compressor bearing systems the presence of refrigerant dissolved in the oil greatly influences the performance and reliability of the compressor due to the outgassing experienced by sudden changes in temperature and pressure resulting in a two-phase mixture with density and viscosity strongly affecting the lubricant characteristics. A general understanding of the oil-refrigerant mixture flow is crucial in developing lubrication models to be used in analysis and simulation of fluid mechanics problems inside the compressor. In the present investigation the refrigeration oil flow with refrigerant outgassing is explored experimentally. A mixture of oil saturated with refrigerant is forced to flow in two straight horizontal tubes of constant diameter. One tube is used for flow visualization and the other is instrumented for pressure and temperature measurements. At the tubes inlet liquid state prevails and as flow proceeds the pressure drop reduces the gas solubility in the oil and outgassing occurs. Initially small bubbles are observed and eventually the bubble population reaches a stage where foaming flow is observed. The flow visualization allowed identification of the two-phase flow regimes experienced by the mixture. Pressure and temperature distributions are measured along the flow and from that mixture quality and void fraction were estimated.

Analytical Modeling of Outward Solidification With Convective Boundary in Cylindrical Coordinates

2020 ◽  
Author(s):  
Minghan Xu ◽  
Saad Akhtar ◽  
Ahmad F. Zueter ◽  
Mahmoud A. Alzoubi ◽  
Agus P. Sasmito
Keyword(s):  
Moving Boundary ◽  
Two Phase ◽  
Convective Boundary ◽  
Interface Motion ◽  
Stefan Number ◽  
Melting Phenomenon ◽  
Approximate Analytical Solutions ◽  
Highly Nonlinear ◽  
Solid Liquid Interface ◽  
Solid Liquid

Abstract Solidification consists of three stages at macroscale: subcooling, freezing and cooling. Classical two-phase Stefan problems describe freezing (or melting) phenomenon initially not at the fusion temperature. Since these problems only define subcooling and freezing stages, an extension to characterize the cooling stage is required to complete solidification. However, the moving boundary in solid-liquid interface is highly nonlinear, and thus exact solution is restricted to certain domains and boundary conditions. It is therefore vital to develop approximate analytical solutions based on physically tangible assumptions, like a small Stefan number. This paper proposes an asymptotic solution for a Stefan-like problem subject to a convective boundary for outward solidification in a hollow cylinder. By assuming a small Stefan number, three temporal regimes and four spatial layers are considered in the asymptotic analysis. The results are compared with numerical method. Further, effects of Biot numbers are also investigated regarding interface motion and temperature profile.

THE EFFECTS OF NOZZLE NUMBER AND OUTLET GEOMETRY ON GRINDING PROCESS WITH MINIMUM QUANTITY COOLING (MQC) BY NANOFLUID

2021 ◽  
pp. 2150058
Author(s):  
HOOMAN ABIYARI ◽  
MOHAMMAD MAHDI ABOOTORABI
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Transfer Functions ◽  
Cutting Temperature ◽  
Nozzle Geometry ◽  
Grinding Process ◽  
Nozzle Outlet ◽  
Outlet Cross Section ◽  
Minimum Quantity ◽  
High Heat Transfer

Machining with minimum quantity lubrication (MQL) or minimum quantity cooling (MQC) as a subset of green machining is a process in which small volume fluid of high lubrication and cooling properties alongside high pressure air is used in the material removal process. The heat generated in the grinding process has a great impact upon the workpiece quality. Serving lubrication and heat transfer functions, cutting fluids have an essential role in reducing the temperature and thus improving the process of grinding. In this research, nanofluid made of graphene nanoparticles in water-based fluid as a cutting fluid of high heat transfer is utilized to investigate the effects of nozzle number and nozzle geometry of the MQC system on the cutting temperature and surface roughness of the workpiece. The effect of geometry and number of nozzles on grinding with MQC has not been studied so far. The study findings show that the nozzle outlet cross-section of rectangular, compared to circular, decreases the surface roughness and temperature by 30% and 36%, respectively. Moreover, compared to the single nozzle, the use of three nozzles results in a decrease of 19% and 31.7% in the surface roughness and temperature. Under the same machining conditions, the MQC method by 0.15[Formula: see text]wt.% nanofluid of graphene in water using a rectangular nozzle outlet of 1.2[Formula: see text]mm width makes surface roughness and temperature reduced by 67.2% and 48.3% compared to the dry condition, whereas decreased by 13.4% and 8.8% compared to the wet method, respectively.

Multiphase Reactions and Reactors

2001 ◽  
Author(s):  
L. K. Doraiswamy
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
Complete Classification ◽  
Catalytic Reactions ◽  
Two Phase ◽  
Multiphase Reactions ◽  
Liquid Phases ◽  
Three Phase ◽  
Solid Form

The first three chapters of this part dealt with two-phase reactions. Although catalysts are not generally present in these systems, they can be used in dissolved form in the liquid phase. This, however, does not increase the number of phases. On the other hand, there are innumerable instances of gas-liquid reactions in which the catalyst is present in solid form. A popular example of this is the slurry reactor so extensively employed in reactions such as hydrogenation and oxidation. There are also situations where the solid is a reactant or where a phasetransfer catalyst is immobilized on a solid support that gives rise to a third phase. A broad classification of three-phase reactions and reactors is presented in Table 17.1 (not all of which are considered here). This is not a complete classification, but it includes most of the important (and potentially important) types of reactions and reactors. The thrust of this chapter is on reactions and reactors involving a gas phase, a liquid phase, and a solid phase which can be either a catalyst (but not a phasetransfer catalyst) or a reactant, with greater emphasis on the former. The book by Ramachandran and Chaudhari (1983) on three-phase catalytic reactions is particularly valuable. Other books and reviews include those of Shah (1979), Chaudhari and Ramachandran (1980), Villermaux (1981), Shah et al. (1982), Hofmann (1983), Crine and L’Homme (1983), Doraiswamy and Sharma (1984), Tarmy et al. (1984), Shah and Deckwer (1985), Chaudhari and Shah (1986), Kohler (1986), Chaudhari et al. (1986), Hanika and Stanek (1986), Joshi et al. (1988), Concordia (1990), Mills et al. (1992), Beenackers and Van Swaaij (1993), and Mills and Chaudhari (1997). Doraiswamy and Sharma (1984) also present a discussion of gas-liquid-solid noncatalytic reactions in which the solid is a reactant. In Chapter 7 we saw how Langmuir-Hinshelwood-Hougen-Watson (LHHW) models are normally used to describe the kinetics of gas-solid (catalytic) or liquid-solid (catalytic) reactions, and in Chapters 14 to 16 we saw how mass transfer between gas and liquid phases can significantly alter the rates and regimes of these two-phase reactions.

Study on Influence of Nozzle Structure on Flow in Diesel Nozzle Orifice

2012 ◽  
Vol 246-247 ◽  
pp. 127-130
Author(s):  
Bing Li ◽  
Xue Song Hu ◽  
Xiao Feng Cao ◽  
Gui Qi Jia ◽  
Fang Xi Xie ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Internal Flow ◽  
Key Factors ◽  
Complex Flow ◽  
Two Phase ◽  
Nozzle Orifice ◽  
Fuel Flow ◽  
Flow Features ◽  
Diesel Nozzle ◽  
Nozzle Hole

The fuel flow characteristics in diesel nozzle orifice are key factors to the atomization of fuel near the nozzle orifice. In the paper, two-phase flow model is used to simulate the complex flow features in nozzle orifice, and to study the influences of the relative position of nozzles orifice axis and nozzle axis, and inclination angle of nozzle hole on the internal flow feature.

Compositional Simulation of Two-Phase Flows for Pipeline Depressurization

SPE Journal ◽  
2017 ◽  
Vol 22 (04) ◽  
pp. 1242-1253 ◽  
Author(s):  
Luigi Raimondi
Keyword(s):  
Numerical Solution ◽  
Mass Balance ◽  
Stokes Equations ◽  
Dynamic Pressure ◽  
Gas Production ◽  
Fluid Composition ◽  
Two Phase ◽  
Compositional Approach ◽  
Liquid Phases ◽  
System Pressure

Summary The simulation of multiphase flow, considered in the case of coexisting vapor and liquid phases, is an important topic in engineering for the design of oil-and-gas production and transportation facilities. This paper presents the development of a compositional approach for the dynamic calculation of multiphase flows in pipelines. This approach can be defined as “full compositional,” because the vapor and liquid phases are described by taking into account the chemical composition, presenting points of interest from both the theoretical and the practical points of view. Physical properties required are calculated at each integration timestep with the actual phase compositions instead of relying on property tables previously generated from a single constant fluid composition. With this approach, in the numerical solution of the conservative two-phase-flow equations, the congruency between the dynamic pressure, calculated by solving the Navier-Stokes equations at constant temperature, and the thermodynamic pressure of the system becomes a critical constraint. In the numerical solution, the overall mass balance defined by means of the vapor- and liquid-phase densities is verified with respect to the mass balance of each chemical component involved, and the system pressure obtained from the solution of the momentum equations is always compared with the thermodynamic value defined by mass balance. Of the numerous test cases created for model validation, three of them (focused on fast depressurizations) are presented and discussed. Similar examples are not available in the literature as solutions of the current “state-of-the-art” commercial pipeline simulators.

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