Topic

# Nozzle

About: Nozzle is a(n) research topic. Over the lifetime, 158675 publication(s) have been published within this topic receiving 893026 citation(s). The topic is also known as: spout.

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TL;DR: In this article, the authors present a comprehensive survey emphasizing the engineering applications and empirical equations, presented for the prediction of heat and mass transfer coefficients within a large and technologically important range of variables.

Abstract: Publisher Summary Heating or cooling of large surface area products is often carried out in devices consisting of arrays of round or slot nozzles, through which air impinges vertically upon the product surface. This chapter presents a comprehensive survey emphasizing the engineering applications and empirical equations, presented for the prediction of heat and mass transfer coefficients within a large and technologically important range of variables. The local variations of the transfer coefficients are based on the experimental data for single round nozzles (SRN), arrays of round nozzles (ARN), single slot nozzles (SSN), and arrays of slot nozzles (ASN). The variation of local transfer coefficients is graphically represented. It also explores how to apply these equations in heat exchanger and dryer design as well as in optimization. The flow field of impinging flow is diagrammatically represented. External variables influencing heat and mass transfer in impinging flow depends on mass flow rate, kind and state of the gas and on the shape, size, and position of the nozzles relative to each other and to the solid surface. The design of high-performance arrays of nozzles is also discussed.

1,462 citations

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TL;DR: In this article, the authors derived a correlation for the Nusselt number of the form suggested by this evidence using a selection of the data and showed that this exponent should be a function of nozzle-to-plate spacing and of the radial displacement from the stagnation point.

Abstract: Experimental data for the rate of heat transfer from impinging turbulent jets with nozzle exit Reynolds numbers in the range of 5,000–124,000 have been collated and critically reviewed from the considerable body of literature available on the subject. The geometry considered is that of a single circular jet impinging orthogonally onto a plane surface for nozzle-to-plate distances from 1.2–16 nozzle diameters and over a flow region up to six nozzle diameters from the stagnation point. Existing correlations for local heat transfer coefficient express Nusselt number as a function of nozzle exit Reynolds number raised to a constant exponent. However, the available empirical data suggest that this exponent should be a function of nozzle-to-plate spacing and of the radial displacement from the stagnation point. A correlation for Nusselt number of the form suggested by this evidence has been derived using a selection of the data. The review also suggests that the Nusselt number is independent of nozzle-to-plate spacing up to a value of 12 nozzle diameters at radii greater than six nozzle diameters from the stagnation point. The results from a simple extrapolation for obtaining heat transfer coefficients in the wall jet region compare favourably with published data.

944 citations

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13 May 1994

TL;DR: In this paper, an ultrasonic oscillator drives a tool at a set frequency and an amplitude control runs the oscillator to set the vibration level, and a frequency regulator joins the amplitude and oscillator.

Abstract: An ultrasonic oscillator drives a tool at a set frequency. An amplitude control runs the oscillator to set the vibration level. A frequency regulator joins the amplitude and the oscillator. A control feedback loop, in the frequency regulator, keeps handpiece linear dynamics. An operational transconductance amplifier, in the oscillator, governs gain of the loop. A circuit connects to the control to retard the rate of current application over time to the amplifier. The circuit has switching to either retard the rate or reset for start up. The amplifier is a current output device with current directly proportional to the bias current and input voltage with bias as gain change for the loop. The circuit limits the bias to the amplifier to modify frequency response and output current. A capacitor delays application of the bias to the amplifier. Replaceable tools of various lengths or shapes positioned along an axis vibrate for surgery at the frequency and a wave length. Tools longer than one wavelength and of configurations tuned to oscillate around the frequency resonate as a function of their material, length and configuration. A flue surrounds the tool and has a hollow elongate semi rigid central body about an axis with a funnel, at one end thereof and a nozzle, at the other to direct annular irrigant/coolant flow therethrough. The funnel and nozzle are resilient. Reinforcing ridges, inside the nozzle, act to maintain concentricity between the flue and nozzle tip and channel irrigant thereabout.

785 citations

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TL;DR: A new valveless fluid pump has been designed and tested that consists of two fluid diffuser/nozzle elements on each side of a chamber volume with an oscillating diaphragm that creates a one-way fluid flow.

Abstract: A new valveless fluid pump has been designed and tested. The pump consists of two fluid diffuser/nozzle elements on each side of a chamber volume with an oscillating diaphragm. The vibrating diaphragm produces an oscillating chamber volume, which together with the two fluid-flow-rectifying diffuser/nozzle elements, creates a one-way fluid flow. A micropump prototype with a chamber diameter of 19 mm with conical diffuser/nozzle elements has been built and tested. The maximum liquid flow rate is 16 ml/min and the maximum pump pressure is 2 m H 2 O. The pump frequency is of the order of 100 Hz.

688 citations

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TL;DR: In this paper, the shape and charge density of a steady jet as it thins from a millimeter-scale nozzle is calculated and combined with the stability analysis to predict scaling laws for the jet behavior and to produce operating diagrams for when electrospinning occurs.

Abstract: Electrospinning is a process in which solid fibers are produced from a polymeric fluid stream (solution or melt) delivered through a millimeter-scale nozzle. This article uses the stability theory described in the previous article to develop a quantitative method for predicting when electrospinning occurs. First a method for calculating the shape and charge density of a steady jet as it thins from the nozzle is presented and is shown to capture quantitative features of the experiments. Then, this information is combined with the stability analysis to predict scaling laws for the jet behavior and to produce operating diagrams for when electrospinning occurs, both as a function of experimental parameters. Predictions for how the regime of electrospinning changes as a function of the fluid conductivity and viscosity are presented.

686 citations