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Showing papers on "Nozzle published in 2021"


DOI
20 Oct 2021
TL;DR: Inkjet printing is the most widespread technological application of microfluidics and is characterized by its high drop productivity, small volumes, and extreme reproducibility as mentioned in this paper, however, it is not suitable for large volumes.
Abstract: Inkjet printing is the most widespread technological application of microfluidics. It is characterized by its high drop productivity, small volumes, and extreme reproducibility. This review gives a...

142 citations


Journal ArticleDOI
TL;DR: In this article, a computational method is applied to examine the impacts of coaxial hybrid air and fuel jets on fuel mixing at the supersonic cross-flow of Mach = 4.

67 citations


Journal ArticleDOI
TL;DR: In this article, the performance and emission characteristics of a dual-fuel diesel/Honge Oil Methyl Ester (HOME)-PG operated CI engine has been studied and the injector nozzles with 4, 5, and 6 holes (diameter of 02, 025, and 03 mm) were analyzed.
Abstract: The improvement in performance has been observed by changing the injector nozzle's geometry of the dual-fuel liquid–gas engine The combined effect of injector parameters and producer gas (PG) derived from the redgram stalk on the performance and emission characteristics of a dual-fuel diesel/Honge Oil Methyl Ester (HOME)-PG operated CI engine has been studied The injector nozzles with 4, 5, and 6 holes (diameter of 02, 025, and 03 mm) were analyzed Diesel-PG operation with 4 holes, 025 mm diameter nozzle and HOME-PG operation with 6 holes, 025 mm diameter nozzle resulted in better performance and lower emissions Diesel-PG operation has 45% higher BTE (brake thermal efficiency) with a 4 hole nozzle and 07% higher for a 025 mm diameter 6 holes nozzle than HOME-PG operation The HOME-PG operation results showed that the with an injection opening pressure of 240 bar, 6-hole nozzle, and a diameter of 025 mm have an improved BTE of 58% with emission levels 15–30% lower than those of other geometries

64 citations


Journal ArticleDOI
TL;DR: In this article, a ground-based experimental investigation of the gas-atomized spray cooling using various micro-structured surfaces and a flat surface is provided and discussed, and a cooling correlation of gas-atomic spray cooling upon micro-structure surfaces is provided with a relative error within ±9%.

47 citations


Journal ArticleDOI
TL;DR: In this article, the effect of the inlet steam superheat degree in steam condensing flow through the International Wet Steam Experimental Project (IWSEP) nozzle was investigated experimentally and numerically.

46 citations


Journal ArticleDOI
Xuewen Cao1, Dan Guo1, Wenjuan Sun1, Pan Zhang1, Gaoya Ding1, Jiang Bian1 
TL;DR: In this paper, a cleaner approach for removing CO2 and H2S from highly acid natural gas by supersonic separation technology was proposed, and the effects of nozzle structure, swirl angle of static vanes and inlet parameters on the refrigeration performance of the nozzle and the separation characteristics of the swirl device were systematically investigated.

43 citations


Journal ArticleDOI
TL;DR: In this paper, a fluid-structure coupling numerical model of an oil-jet lubricated cylindrical roller bearing (CRB) in a high power gearbox is developed, in which the volume of fluid (VOF) method and slip mesh model are used.

43 citations


Journal ArticleDOI
TL;DR: In this article, X-ray micro-tomography (µCT) scans are performed on the raw filament, in-nozzle melted filament, extruded printing bead and on-bed printing bead to trace the through-process evolution of fibres and voids for the specific nozzle used therein.
Abstract: This paper for the first time presents experimental results for fibre flow and void formation during 3D printing of short fibre reinforced thermoplastic composites by fused filament fabrication (FFF). Short carbon fibre T300 reinforced nylon-6 composite is selected as the printing material. X-ray micro-tomography (µCT) scans are performed on the raw filament, in-nozzle melted filament, extruded printing bead and on-bed printing bead to trace the through-process evolution of fibres and voids for the specific nozzle used therein. Qualitative visualisation of voids fraction and fibre orientation, length and fraction, as well as quantitative analysis are carried out using image processing techniques. The results show that the orientation and volume fraction of fibres vary with different internal geometry of the nozzle and fibre misalignment occurs in the on-bed printing bead because the relative motion between the nozzle and the print bed disturbs the flow field. Also the fibre length decreases slightly during the printing process due to the collision between fibre and nozzle wall when the melted materials pass the nozzle. For the void volume fraction, most voids are generated when the melted filament is extruded from the nozzle, and porosity decreases in the on-bed printing bead. The reported experimental data of through-process evolution of fibre flow and void formation can also be used for benchmarking and/or validating computational models for 3D printing of short fibre reinforced polymer composites.

40 citations


Journal ArticleDOI
TL;DR: In this paper, a multiscale method was proposed to investigate the atomization characteristics of the pressure-swirl nozzle for dust reduction, which distinguishes between internal flow field, primary atomization and secondary atomization.

39 citations


Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the performance of two types of radiofrequency (RF) antennas for two different configurations of rf antennas in terms of power transfer efficiency and imparted thrust.
Abstract: Development of a magnetic nozzle radiofrequency (rf) plasma thruster has been one of challenging topics in space electric propulsion technologies. The thruster typically consists of an rf plasma source and a magnetic nozzle, where the plasma produced inside the source is transported along the magnetic field and expands in the magnetic nozzle. An imparted thrust is significantly affected by the rf power coupling for the plasma production, the plasma transport, the plasma loss to the wall, and the plasma acceleration process in the magnetic nozzle. The rf power transfer efficiency and the imparted thrust are assessed for two types of rf antennas exciting azimuthal mode number of $$m=+1$$ and $$m=0$$ , where propellant argon gas is introduced from the upstream of the thruster source tube. The rf power transfer efficiency and the density measured at the radial center for the $$m=+1$$ mode antenna are higher than those for the $$m=0$$ mode antenna, while a larger thrust is obtained for the $$m=0$$ mode antenna. Two-dimensional plume characterization suggests that the lowered performance for the $$m=+1$$ mode case is due to the plasma production at the radial center, where contribution on a thrust exerted to the magnetic nozzle is weak due to the absence of the radial magnetic field. Subsequently, the configuration is modified so as to introduce the propellant gas near the thruster exit for the $$m=0$$ mode configuration and the thruster efficiency approaching twenty percent is successfully obtained, being highest to date in the kW-class magnetic nozzle rf plasma thrusters.

37 citations


Journal ArticleDOI
TL;DR: In this article, the relationship between pre-chamber jet and main chamber ignition in the prechamber combustion (PCC) of an optical engine, fueled with methane and equipped with two rows of orifices was studied.

Journal ArticleDOI
TL;DR: In this paper, an instrument for initial expansion energy of released gas (IEERG) measurement was developed and compared with previous setups, the new one which is equipped with three convergent nozzles and quick release mechanism gets improved in data acquisition and gas sealing and releasing performance.
Abstract: Coal and gas outburst is a violent disaster driven by released energy from gas desorption. The initial expansion energy of released gas (IEERG) is a new method to predict coal and gas outburst. In this paper, an instrument for IEERG measurement was developed. Compared with previous setups, the new one which is equipped with three convergent nozzles and quick-release mechanism gets improved in data acquisition and gas sealing and releasing performance. To comprehensively know the effect of gas pressure, particle size, and nozzle area on IEERG, a series of experiments were carried out with this new setup. The variable control test results indicated that the gas pressure-IEERG curves remain the linear trend and the particle size-IEERG curves maintain the negative exponential trend for nozzle areas at 1.13, 2.26, and 3.39 mm2, respectively. The increase in nozzle area leads to deceases in value of IEERG and absolute value of slope of fitting curves in each test. In addition, the orthogonal experiment showed that the influence of gas pressure, nozzle area, and particle size on IEERG decreases in turn. Only gas pressure had a marked impact on IEERG. This work offers great importance in improving the accuracy of prediction of coal and gas outburst.

Journal ArticleDOI
TL;DR: The nozzle diameter was found to be the most significant parameter affecting the bending and compression performance of the printed PEEK samples, followed by printing speed and nozzle temperature, and different parameter combinations have been found to obtain optimal mechanical properties.
Abstract: Design of experiments was employed to investigate the combinations of 3D-printing parameters for Polyether ether ketone (PEEK) with a fused filament fabrication (FFF) process and to quantitatively evaluate the quality of 3D printed parts. This research was conducted using a newly developed FFF 3D printer and PEEK filament. Standard PEEK parts were 3D printed for bending and compression tests. Based on the Box-Behnken design, a three factors based experiment was designed using the Response Surface Methodology (RSM). Nozzle diameter, nozzle temperature and printing speed were involved. The density and dimensional accuracy of these printed parts were evaluated, and the bending and compression tests were conducted. The nozzle diameter was found to be the most significant parameter affecting the bending and compression performance of the printed PEEK samples, followed by printing speed and nozzle temperature. The highest accuracy in sample width was obtained with a 0.6 mm nozzle while the most accurate diameter was obtained with a 0.4 mm nozzle. A combination of a 0.4 mm nozzle diameter, 430 °C nozzle temperature and printing speed of 5 mm/s was beneficial to get the densest samples and therefore the highest bending strength; a reduction of internal defects was achieved with a 0.2 mm nozzle, a higher nozzle temperature of 440 °C and slower printing speed leading to better bending modulus. The best compression properties were achieved with a 0.6 mm nozzle, with relatively low influence of the other parameters. Different parameter combinations have been found to obtain optimal mechanical properties. Optimized parameters for better dimension accuracy of small additively manufactured PEEK parts were also achieved depending on the shape of the specimens.

Journal ArticleDOI
TL;DR: In this article, the characteristics of acoustic tones near the nozzle of jets were investigated for Mach numbers between, and they were found to be very similar to the ones reported in this paper.
Abstract: The characteristics of acoustic tones near the nozzle of jets are investigated for Mach numbers between .

Journal ArticleDOI
TL;DR: In this paper, the authors used the microjets in the form of an orifice of a 1-mm diameter to inject the air in the base flows and located at base area of 90° intervals as a control mechanism.
Abstract: In high-speed fluid dynamics, the control of base pressure finds many engineering applications such as automobile industry and defense applications. Several studies have been reported on passive control using devices like cavities, ribs, aerospikes, etc. in the last three decades. Therefore, the present research focuses on active control uses the microjets in the form of an orifice of a 1 mm diameter to inject the air in the base flows and located at base area of 90° intervals as a control mechanism. Since the air is drawn from the main settling chamber, the NPR will be the same as the respective NPRs used for tests. Experiments were conducted in the presence and absence of the microjets for area ratio 3.24 and L/D ratios from 10 to 1 at Mach numbers 1.87, 2.2, and 2.58. The parameters were optimized using the design of experiments (DOE) approach. Three parameters have been selected for the flow and the DOE. An L9 orthogonal array, multiple linear regression, and confirmation tests were performed to analyze the experimental results. The developed models are statistically suitable and accomplished in producing reasonable predictions for both cases. Besides, a computational fluid dynamics method has been utilized and validated by the experimental results. The k–Ɛ turbulent model is used to analyze the simulation results. According to the present results, it is evident that for a given parameter, an L/D ratio is the most significant impacting to a maximum increment or decrement of a base pressure.

Journal ArticleDOI
01 Jan 2021-Fuel
TL;DR: In this article, a simulation study was conducted to investigate influences of asymmetric structural characteristics on interior nozzle flow in a multi-hole marine low-speed diesel injector, and the simulation results illustrate that both mass flow rates and flow discharge coefficients of two holes on both sides are larger than those of two hole in the middle with increasing hole entrance corner radius (R), hole diameter (D), and hole length.

Journal ArticleDOI
15 Dec 2021-Energy
TL;DR: In this paper, the influence of a primary nozzle on steam ejector performance considering phase change processes is analyzed and validated in detail against experimental data of supersonic nozzles and steam ejectors available in the literature.

Journal ArticleDOI
Yang Liu1, Xuewen Cao1, Jian Yang1, Yuxuan Li1, Jiang Bian1 
TL;DR: In this article, a mathematical model of methane-water vapor condensation was established to study the energy separation and condensation characteristics of wet natural gas in the nozzle, and the results showed that the shock wave/boundary layer interaction leads to an energy separation phenomenon.

Journal ArticleDOI
TL;DR: In this paper, a variable-geometry nozzle is proposed to improve the surface finish quality in 3DCP using a developed variable geometry nozzle that can directly control the extrudate geometry during the printing process at every layer.
Abstract: The 3D Concrete Printing technology (3DCP) has developed fast in the past few years. Compared to conventional construction method, the 3DCP technology offers an advantage in speed and cost. However, the surface of a structure from 3DCP technology requires post-finishing processes as the direct outcome suffers from low quality surface finish problem, such as jagged surface and staircase effect. This study aims to improve the surface finish quality in 3DCP using a developed novel variable-geometry nozzle that can directly control the extrudate geometry during the printing process at every layer. The nozzle assembly features an adjustable nozzle outlet geometry that can be controlled along the process. The mechanism requires a slicing algorithm to determine the extrudate geometry at every layer based on the designated printed structure. The corresponding algorithm was also developed and will be presented in this paper. Subsequently, the functionality of the proposed method was validated with a case study of manufacturing a structure with curved outer-surface geometry (an arch).

Journal ArticleDOI
01 Apr 2021-Fuel
TL;DR: In this article, an experimental activity was carried out by means of a constant volume vessel test bench with optical accesses to compare the spray evolution and sizing with and without duct adoption, over a wide range of vessel thermodynamic conditions and injection pressures.

Journal ArticleDOI
TL;DR: In this paper, the authors explored the mechanisms that contribute to nozzle clogging in fiber-filled polymer inks with extrusion-based additive manufacturing processes, which limits the quantity of fibers that can be added to the matrix, part fidelity, and geometric accuracy of the printing process.
Abstract: Nozzle clogging frequently occurs while printing fiber-filled polymer inks with extrusion-based additive manufacturing processes, which limits the quantity of fibers that can be added to the matrix, part fidelity, and geometric accuracy of the printing process. Both in situ X-ray radiography and ex situ X-ray computed tomography were used to explore the mechanisms that contribute to nozzle clogging. Three inks were considered, with fiber volume fractions ranging from 1% to 5.75%, and nominal fiber lengths from 150 to 470 µm. These results showed that the specific mechanisms that produced the clog depended substantially on the fiber volume fraction, fiber length and nozzle geometry. Specific clogging mechanisms included the log-jam pileup of misoriented fibers near the nozzle tip, the lodging of a fiber entanglement in the nozzle tip, and the accumulation of misoriented fibers at step-like reductions in the nozzle profile. Suggestions to reduce the prevalence of nozzle clogging are presented.

Journal ArticleDOI
TL;DR: In this paper, a review of the materials and machine parameters associated with FDM printing and highlights the effect of the mechanical and thermal properties of the material on the durability and strength of the printed objects.

Journal ArticleDOI
04 May 2021
TL;DR: A novel 3D bioprinting method based on the principle of acoustic droplet ejection (ADE) that minimizes critical shear stress and holds promise for cell-preserving creation of complex and individualized cell-laden 3D hydrogel structures.
Abstract: Bioprinting allows the manufacture of complex cell-laden hydrogel constructs that can mature into tissue replacements in subsequent cell culture processes. The nozzles used in currently available bioprinters limit the print resolution and at dimensions below 100 µm clogging is expected. Most critically, the reduction of nozzle diameter also increases shear stress during printing. At critical shear stress, mechanical damage to printed cells triggers cell death. To overcome these limitations, a novel 3D bioprinting method based on the principle of acoustic droplet ejection (ADE) is introduced here. The absence of a nozzle in this method minimizes critical shear stress. A numerical simulation reveals that maximum shear stress during the ADE process is 2.7 times lower than with a Ø150 µm microvalve nozzle. Printing of cell clusters contained in droplets at the millimeter length scale, as well as in droplets the size of a single cell, is feasible. The precise 3D build-up of cell-laden structures is demonstrated and evidence is provided that there are no negative effects on stem cell morphology, proliferation, or differentiation capacities. This multiscale acoustic bioprinting technique thus holds promise for cell-preserving creation of complex and individualized cell-laden 3D hydrogel structures.

Journal ArticleDOI
TL;DR: In this article, a thermal management strategy for electronic chips based on a combination of a flat-plate heat pipe (FPHP) and spray cooling was designed to improve the heat dissipation performance of the condensation section of the heat pipes.

Journal ArticleDOI
TL;DR: In this article, the effects of the nozzle inclined angle and diameter as well as the heat release rate on the characteristics of syngas jet flame were investigated. And the model can be used to estimate the horizontal extension length of the syngga jet flame for nozzles with different diameters and inclined angles.

Journal ArticleDOI
Wang Zhi1, Guangming Zhang1, Huang Hui1, Lei Qian1, Xiaoling Liu1, Hongbo Lan1 
TL;DR: In this article, a self-induced electric-field-driven jet printing was proposed to overcome the mandatory requirement of nozzle conductivity in the conventional electrohydrodynamic (EHD) jet printing.
Abstract: To overcome the mandatory requirement of nozzle conductivity in the conventional electrohydrodynamic (EHD) jet printing, this paper proposed a self-induced electric-field-driven jet printing for fa...

Journal ArticleDOI
15 Mar 2021-Fuel
TL;DR: In this article, the influence of different fuel injection strategies on flame propagation and combustion characteristics in a glow plug assisted direct-injection natural gas engine was investigated using the KIVA-3V code with added improved emissions models.

Journal ArticleDOI
09 Nov 2021-Fuel
TL;DR: In this article, a negative pressure jet dust-removal water curtain based on the NPP principle was developed to address coal mine air pollution problem, and the air suction volume of the dust hood was as high as 13.74m3/min, and proportion of the spray field with a cross-section concentration at the water curtain of more than 104 mg/m3 accounted for 92.4%.

Journal ArticleDOI
TL;DR: In this article, the authors proposed and compared two methods, which are based on existing TO techniques that enable control of minimum and maximum member size, and of minimum cavity size, for large-scale additive manufacturing.
Abstract: Additive Manufacturing (AM) processes intended for large scale components deposit large volumes of material to shorten process duration. This reduces the resolution of the AM process, which is typically defined by the size of the deposition nozzle. If the resolution limitation is not considered when designing for Large-Scale Additive Manufacturing (LSAM), difficulties can arise in the manufacturing process, which may require the adaptation of the deposition parameters. This work incorporates the nozzle size constraint into Topology Optimization (TO) in order to generate optimized designs suitable to the process resolution. This article proposes and compares two methods, which are based on existing TO techniques that enable control of minimum and maximum member size, and of minimum cavity size. The first method requires the minimum and maximum member size to be equal to the deposition nozzle size, thus design features of uniform width are obtained in the optimized design. The second method defines the size of the solid members sufficiently small for the resulting structure to resemble a structural skeleton, which can be interpreted as the deposition path. Through filtering and projection techniques, the thin structures are thickened according to the chosen nozzle size. Thus, a topology tailored to the size of the deposition nozzle is obtained along with a deposition proposal. The methods are demonstrated and assessed using 2D and 3D benchmark problems.

Journal ArticleDOI
TL;DR: In this paper, a semianalytical numerical method is proposed for rapid and assumption-less calculations of the magnetic field because of a thick coil with rectangular cross section, and the method is extended for the proposal of a three-coil setup, where divergence angle of magnetic field lines is readily controlled in-flight to provide the flexibility to modify the output magnetic thrust and the nozzle's efficiency.
Abstract: Magnetic nozzles with their contactless feature have opened new grounds for long-distance space travels. For quicker mission completions along with improving system reliability, it becomes necessary to design robust systems that exhibit the ability to confine thrust. A semianalytical numerical method is proposed for rapid and assumption-less calculations of the magnetic field because of a thick coil with rectangular cross section. The method is extended for the proposal of a three-coil setup, where divergence angle of the magnetic field lines is readily controlled in-flight to provide the flexibility to modify the output magnetic thrust and the nozzle’s efficiency.