Comparative study of flow characteristics within asymmetric multi hole VCO and SAC nozzles

Moro, Adams; Zhou, Qun; Xue, Fuying

doi:10.1016/j.enconman.2016.11.048

Cited by 15 publications

(8 citation statements)

References 28 publications

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“…Since there are two types of dust sampling precatchers used, there are two corresponding methods for calculating dust density. 26,27 ffi Calculation of dust density when using a full dust pre-catch…”

Section: Calculation Of Dust Densitymentioning

confidence: 99%

Design and optimization of inner-rotation nozzle in negative pressure duster

Zhai

Ren

Wei

2019

Advances in Mechanical Engineering

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This article proposes a design and experimental method of a new inner-rotation nozzle. First, the design model of the inner-rotation nozzle was established based on Abramovich’s maximum flow principle and high-pressure water jet crushing theory. Considering the specific conditions of the negative pressure duster, the reference values of nozzle structure parameters are calculated. The simulation is conducted for studying the relationship between the nozzle’s structure parameters and its performance including water flow velocity at nozzle outlet, atomization effects, and so on. By orthogonal experiment, the reasonable nozzle structure parameters were obtained by analyzing the speed of flow, the amount of air, and so on. Then, a series of nozzles were machined with different size shells and cores. In order to select out the optimum matching of nozzle cores and shells, an experimental system is established. Considering the installation location, wind speed, liquid–gas ratio, and other factors, the optimum matching of the shell core was chosen. At the same time, the application test of the negative pressure duster was carried out on the fully mechanized mining face. The research results show that the removal rate of pulverized coal has a higher improvement, and provides a theoretical basis for the design of negative pressure duster.

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Section: Calculation Of Dust Densitymentioning

confidence: 99%

Design and optimization of inner-rotation nozzle in negative pressure duster

Zhai

Ren

Wei

2019

Advances in Mechanical Engineering

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“…In the current scheme, such a concept is applied locally, by means of the separate multi-phase nozzle flow simulation ( Figure 5, left). For each "j" face of the nozzle orifice, the rate dR j /dt is calculated from the two-phase nozzle flow simulation; the atomization length scale L A,j is equal to the turbulent length scale L T,j as reported in Equation (8). The turbulent length-scale L T,j and the atomization time scale τ A,j are determined locally for each j face.…”

Section: Core Injection Approach Under Nozzle Flow Local Informationmentioning

confidence: 99%

“…Significant efforts have been devoted at comparing sac and VCO nozzles, focusing the attention on the internal nozzle flow, on the rate of injection and on the spray behavior [6][7][8]. Besides some advantages, the major drawback of the VCO layout is represented by the irregularities of the spray that occur at low needle lift; these abnormalities assume relevance because they are related to the Appl formation of particulate matter [1].…”

Section: Introductionmentioning

confidence: 99%

On the Link between Diesel Spray Asymmetry and Off-Axis Needle Displacement

et al. 2017

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Abstract:Cutting edge experiments and thorough investigations have pointed out that radial components affect the needle lift of diesel nozzles. So far, the effects of such needle "off-axis" have been investigated within the nozzle and immediately downstream from the hole outlet. Here, the focus has been extended to the spray ambient, far outside a multi-hole VCO (Valve Covered Orifice) nozzle. A reference off-axis configuration of the needle has been defined and used to investigate its effects on the spray, in terms of hole-to-hole differences. Indeed, the spray alterations due to the needle position have been addressed for those factors, such as the velocity-coefficient C V and the area-coefficient C A , able to describe the nozzle flow behavior under needle off-axis. The investigation has been based on 3D-CFD (three-dimensional computational fluid dynamics) campaigns. The modeling of diesel nozzle flow has been interfaced to the Eulerian-Eulerian near-nozzle spray simulation, initializing the break-up model on the basis of the transient flow conditions at each hole outlet section. The dense spray simulation has been on-line coupled to the Eulerian-Lagrangian modeling of the dilute spray region. Quantitative results on each fuel spray have been provided (in terms of penetration and Sauter Mean Diameter). The range of variability within the spray characteristics are expected to vary has been found and reported, providing reference information for lumped parameter models and other related investigations.

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“…Under the same injection conditions, fuel flow inside the orifices of VCO nozzle is more prone to cavitate, and in cavitation conditions, the orifices of VCO nozzle have higher effective injection velocity due to the smaller effective flow area. 29,30 The orifices of mini-sac nozzle have a higher discharge rate both in cavitation and non-cavitation conditions. 27,30 Internal flow in VCO nozzle is more sensitive to needle movement and orifice inclination angle than that in the mini-sac nozzle.…”

mentioning

confidence: 99%

“…29,30 The orifices of mini-sac nozzle have a higher discharge rate both in cavitation and non-cavitation conditions. 27,30 Internal flow in VCO nozzle is more sensitive to needle movement and orifice inclination angle than that in the mini-sac nozzle. 29,30 For asymmetric multi-hole injector, the non-uniformity of flow parameters among the orifices of VCO nozzle is much higher than that for minisac nozzle, especially at small needle lifts on account of the formation of vortex flow in the annular zone between two adjacent orifices.…”

mentioning

confidence: 99%