Atomization Characteristics of Effervescent Atomizer With Two-Aerator Tube

An experimental study was conducted to investigate the atomization characteristics of spray from the effervescent atomizer, which has two-aerator tube. The atomization characteristics were examined through the influence of ALR (Air-to-Liquid Ratio) and the changes of atomizer geometry (nozzle orifice diameter, diffusion angle, mixing chamber volume). PDPA (Phase Doppler Particle Analyzer) was used to evaluate the SMD (Sauter Mean Diameter) and droplet velocity. During the experiments, the mass flow rate of liquid was kept constant at 2.8g/s and the mass flow rate of atomizing air was changed from 0.2 to 0.6g/s. Experimental results showed that SMD is not a linear function of ALR. While SMD is very sensitive to the changes of ALR, the changes of atomizer geometry have little effect on droplet mean diameter. As the effervescent atomizer with two-aerator tube is insensitive to the changes of atomizer geometry, it is expected that the effervescent atomizer with two-aerator tube is capable of requirements of many applications, without the drawbacks of atomization characteristics.

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Predicted performance of a two-phase underwater ramjet with a Laval nozzle

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/1475090218795585 ◽

2018 ◽

Vol 233 (3) ◽

pp. 937-948

Author(s):

Jiarui Zhang ◽

Zhixun Xia ◽

Liya Huang ◽

Likun Ma

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Laval Nozzle ◽

Fluid Model ◽

Bubbly Flow ◽

Engine Performance ◽

Orifice Diameter ◽

Two Phase ◽

Convergent Nozzle

To predict engine performance and further instruct the integral engine design, a more reasonable and accurate numerical model of the two-phase underwater ramjet was introduced in this article by considering the bubble formation process. Two-fluid model was used to examine the bubbly flow in the nozzle and its mathematical model was solved by a fourth-order Runge–Kutta method. Subsequently, the influences of vessel velocity, gas mass flow rate, navigational depth, and orifice diameter of the bubble injector on the performance of the engine were discussed. Results show that, compared with convergent nozzle, Laval nozzle is proved to improve the thrust of the engine, especially at relatively high velocity and gas mass flow rate. With the other conditions fixed, there is an optimum vessel velocity for the ramjet, in which maximum thrust is generated. And a smaller orifice diameter always promotes the engine performance, while this promotion is negligible when the orifice diameter is smaller than 1 mm. Besides, increasing backpressure will cause serious performance drop, which means that the the two-phase underwater ramjet is only efficient for shallow depths.

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Flow Characteristic of Hydraulic Headbox Based on Complementary Pulp Distribution

The Open Mechanical Engineering Journal ◽

10.2174/1874155x01509010733 ◽

2015 ◽

Vol 9 (1) ◽

pp. 733-738

Author(s):

Liu Wei ◽

Ji Xiaohui

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Flow Characteristic ◽

Fluid Dynamic ◽

Maximum Deviation ◽

Improve Performance ◽

Central Section ◽

Mixing Chamber ◽

Two Sides

In order to study the effect of complementary pulp distribution, computational fluid dynamic (CFD) was used to research on flow characteristic of hydraulic headbox based on complementary pulp distribution. Mass flow rate out of mixing chamber and velocity distribution at slice of headbox were experimented. The results show that because of simplified design, there was a little gradient of velocity and pressure which caused non uniform distribution of mass flow rate out of branch pipes. Distribution of mass flow rate was ascended from inlet of header to outlet and the deviation was - 2.33% and 1.82%. There was intense interference between the jets of branch pipes in mixing chamber and the jets could be sufficiently and complementarily mixed in rows and ranks. But the interference in the jets caused the accumulation of the jets in the central section of mixing chamber and mass flow rate out of mixing chamber in the center was higher than the two sides, and the maximum deviation was 0.538%. Distribution of velocity of pulp stock at slice of headbox was very gentle and curve of distribution presented only slight fluctuation. The maximum deviation of velocity was only 0.175%. From the results of the experiment, the test values of mass flow rate out of mixing chamber were inosculated with the calculated values and tested values of velocity at the slice of headbox were in accordance with the calculated values. The results of experiment explained that the method of complementary pulp distribution was reasonable and could obviously improve performance of pulp distribution of hydraulic headbox.

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Evaluation of Mass Flow Rate Distribution in Diesel Fuel Spray by L2F

ASME 2011 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2011-60093 ◽

2011 ◽

Cited By ~ 1

Author(s):

Keisuke Komada ◽

Noritsune Kawaharada ◽

Daisaku Sakaguchi ◽

Hironobu Ueki ◽

Masahiro Ishida

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Diesel Fuel ◽

Nozzle Exit ◽

Evaluation Method ◽

Fuel Spray ◽

Orifice Diameter ◽

Dense Region ◽

Fuel Mass

A laser 2-focus velocimeter (L2F) has been applied for measurements of velocity and size of droplets of diesel spray and an evaluation method of mass flow rate has been proposed. The L2F has a micro-scale probe which consists of two foci. The distance between two foci is 17μm. The data acquisition rate of the L2F has been increased to 15MHz in order to capture every droplet which appears in the measurement volume. The diesel fuel spray injected intermittently into the atmosphere was investigated. The orifice diameter of the injector nozzle was 0.113mm. The injection pressure was set at 40MPa by using a common rail system. Measurements were conducted on ten planes 5 to 25mm downstream from the nozzle exit. It was clearly shown that the velocity of droplet was the highest at the spray center. The size of droplet at the spray center decreased downstream within 15mm from the nozzle exit. The mass flow rate near the spray center was found to be larger than that in the spray periphery region. It was confirmed that the fuel mass per injection evaluated by the proposed method based on the L2F measurement was near to the injected mass in a plane further than 15mm from the nozzle exit. However, fuel mass was underestimated in a plane closer to the nozzle exit. The probability density of infinitesimal distance between surfaces of adjacent droplets increased remarkably near the spray center 5 and 12mm downstream from the nozzle exit. As infinitesimal distance can be thought as an indicator of a highly dense region, it is understood that underestimation of fuel mass near the nozzle exit is due to the highly dense region. The diameter of the region, where the highly dense region was observed, was estimated as an order of 0.2mm in a plane 5mm downstream from the nozzle.

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The Effect of Sauter Mean Diameter Fluctuations on the Heat Release Rate in a Lean-Burn Aero-Engine Combustor

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2019-90321 ◽

2019 ◽

Cited By ~ 1

Author(s):

Nicholas C. W. Treleaven ◽

Andrew Garmory ◽

Gary J. Page

Keyword(s):

Heat Release ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Heat Release Rate ◽

Release Rate ◽

Sauter Mean Diameter ◽

Lean Burn ◽

Thermoacoustic Instability ◽

Mean Diameter

Abstract It has been shown that the fluctuations of pressure caused by a thermoacoustic instability can affect the mass flow rate of air and atomisation of the liquid fuel inside a gas turbine. Tests with premixed flames have confirmed that the fluctuations of the mass flow rate of air can affect the heat release rate through purely aerodynamic phenomenon but little work has been done to test the sensitivity of the heat release rate to changes in the fuel atomisation process. In this study, a lean-burn combustor geometry is supplied with a fuel spray fluctuation of SMD (Sauter mean diameter) of 20% with respect to the mean value and the heat release rate predicted using Large Eddy Simulation (LES) with combustion predicted using a presumed probability density function (PPDF), flamelet generated manifolds (FGM) method. Previous work has shown that at atmospheric conditions the SMD may fluctuate by up to 16% percent and at low frequencies may be reasonably well predicted by using a correlation based on the instantaneous velocity and mass flow rate of air close to the air-blast atomiser. Analysis of the flow fields highlights a complicated spray, flame and wall interaction as being responsible for this observed fluctuation of heat release rate. The heat release rate predicted by the LES shows a 20% fluctuation which implies that even small fluctuations of SMD will significantly contribute to thermoacoustic instabilities.

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