Numerical simulation and experimental study for aerodynamic characteristics and powder transport behavior of novel nozzle

Zhang, Jian; Yang, Lin; Zhang, Wei; Qiu, Junbin; Xiao, Haibing; Liu, Yang

doi:10.1016/j.optlaseng.2019.105873

Cited by 34 publications

(4 citation statements)

References 22 publications

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“…The geometric characteristics of LDMD, which mainly include the width (W), height (H), and contact angle (θ) with the substrate, are shown in Figure 8a. The definitions of these geometric characteristics have been discussed in previous studies [36]. According to the simulation results of the spatial geometric coupling characteristics of the optical powder, the experimental conditions are as follows: keep the carrier gas flow rate constant at 4.0 L/min and change the powder feeding speed for LDMD (the black curve in Figure 8b), and keep the powder feeding speed constant at 4.0 g/min and change the carrier gas flow rate for LDMD (the red curve in Figure 8b).…”

Section: Geometric Characteristics Of Ldmd and The Actual Utilization...mentioning

confidence: 99%

Coupling Characteristics of Powder and Laser of Coaxial Cone Nozzle for Laser Direct Metal Deposition: Numerical Simulation and Experimental Study

Wang

Yang

et al. 2023

Materials

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Laser direct metal deposition (LDMD) enables not only the preparation of high-performance coatings on the surfaces of low-property materials but also the three-dimensional direct manufacturing and re-manufacturing of parts. In the LDMD process, the spatial coupling characteristics of the powder flow and the laser beam are the key factors affecting the forming quality of the cladding layer. Based on the gas–solid two-phase flow theory, a numerical model of coaxial powder feeding was established by CFD. The powder flow characteristics of the lower part of the nozzle, the powder particle motion trajectory, and the optical-powder spatial coupling morphology and law were studied, and the relationship between the powder flow morphology, laser beam, and powder utilization was explored. On this basis, the law between the optical-powder coupling characteristics and the geometric characteristics of the cladding layer is discussed in conjunction with LDMD experiments. The results show that the powder concentration scalar located in the focal plane of the laser beam can be used to visualize the optical-powder coupling morphology. When the powder feeding speed exceeds the loading capacity of the carrier gas flow, the powder concentration in the center of the spot and the powder utilization rate decrease. When the carrier gas flow rate is 4.0 L/min and the powder feeding rate is 4.0 g/min, the best utilization rate achieved is 81.4%. In addition, the H (height) of the cladding layer is more sensitive to changes in the powder concentration than the W (width). These findings provide new ideas for nozzle structure design and the optimization of LDMD parameters.

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Section: Geometric Characteristics Of Ldmd and The Actual Utilization...mentioning

confidence: 99%

Coupling Characteristics of Powder and Laser of Coaxial Cone Nozzle for Laser Direct Metal Deposition: Numerical Simulation and Experimental Study

Wang

Yang

et al. 2023

Materials

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“…The coating thickness at 2.0 m/min cladding speed is about 540 μm, while that at 8.0 m/min is about 360 μm. With weighting before and after coating of the rod [4,22,23], the powder using ratio at cladding speed of 2.0 m/min is around 75.9%, at cladding speed of 8.0 m/min is around 66.7%. It could be found that the sizes of heat affected zone (HAZ) decrease as the cladding speed increases.…”

Section: Laser Cladding Experimentalmentioning

confidence: 99%

Powder Flow Simulation of a Ring Type Coaxial Nozzle and Cladding Experiment in Laser Metal Deposition

Zhou

Yang

Wang

et al. 2022

Preprint

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A 3D whole size numerical model of a ring type coaxial nozzle was established to obtain particle space trajectory and convergence character. The realizable k-ε model was applied in the gas flow phase; the powder flow was coupled to the gas flow by Euler-Lagrange approach as a discrete phase model. Different powder material and particle size range were chosen to calculate the powder concentration distribution. The simulated powder stream morphology was in good agreement with the experimental results of high-speed camera observations. Simulating results show that the using of mean diameter \(\stackrel{-}{\text{d}}\) to replace Rossin–Rammler distribution of particle size could also get an accurate flowing characteristic results based on this model, this replacement could save a lot computational resource and shrinkage the computing time. The existing of coaxial shielding gas can impact the powder mass concentration spatial distribution, maximum value convergence height and spot size of the powder flow directly. For 316L with small particle size and Ni60A with large particle size, we found different change regularity and no linear relationship was found. So it was not suggest change the input volume of coaxial shielding gas without special needs. Combining with the laser cladding experiments of Ni60A, results show that the developed ring type coaxial nozzle could transport powder well and prepare excellent deposited layers, the conditional powder utilization ratio can up to 75.9%.

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“…Feng et al study showed that the cylindrical filling pipe blanking used by reducing the height of the blanking could effectively control the dust [21]. In addition, referring to the device principle and characteristics of powder pneumatic conveying, it not only reduces dust discharge and raw material waste, but is also convenient for conveying and is simple to operate [25,26]. Due to the limitation of pipeline space, dust particles cannot escape the external space.…”

Section: Equipment Principle and Operation Design Ideas And Schemesmentioning

confidence: 99%

A New Coking Coal Charging Method for 6 m Top-Charged Coke Oven: System Design and Experiment

Zhang

2020

Applied Sciences

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Coking with low moisture coal is an important link of energy conservation and coke quality improvement in the coking industry. Aiming at the problems of dust emission and bad accumulation in the coking chamber during coal charging, a new system of coking coal charged into 6 m top-charge coke oven was studied and designed, in which a cylinder with telescopic and high temperature resistance was used to fill the coking chamber with a dense phase continuous flow. The coal transport characteristics, dust emission, and accumulation characteristics were studied through the actual operation of the equipment. The results found that the matching of spiral feeding speed and cylinder lifting speed had an important influence on the transport characteristics, when moisture was 5%, and the control dense phase transport conditions were—cylinder lifting speed of 0.02 m/s and spiral feeding speed control range of [0.31 m/s, 0.50 m/s]. The new device was found to reduce dust emission by 90% per square meter, compared to the traditional. The influence of controllable factors on the accumulation characteristics of coal was studied, and the essential conditions for optimal repose angle and bulk density were obtained through an orthogonal test, the prediction model of accumulation characteristics was established.

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Numerical simulation and experimental study for aerodynamic characteristics and powder transport behavior of novel nozzle

Cited by 34 publications

References 22 publications

Coupling Characteristics of Powder and Laser of Coaxial Cone Nozzle for Laser Direct Metal Deposition: Numerical Simulation and Experimental Study

Coupling Characteristics of Powder and Laser of Coaxial Cone Nozzle for Laser Direct Metal Deposition: Numerical Simulation and Experimental Study

Powder Flow Simulation of a Ring Type Coaxial Nozzle and Cladding Experiment in Laser Metal Deposition

A New Coking Coal Charging Method for 6 m Top-Charged Coke Oven: System Design and Experiment

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