Nozzle Design Research Articles

Versatile Patterning of Liquid Metal via Multiphase 3D Printing.

This paper presents a scalable and straightforward technique for the immediate patterning of liquid metal/polymer composites via multiphase 3D printing. Capitalizing on the polymer's capacity to confine liquid metal (LM) into diverse patterns. The interplay between distinctive fluidic properties of liquid metal and its self-passivating oxide layer within an oxidative environment ensures a resilient interface with the polymer matrix. This study introduces an inventive approach for achieving versatile patterns in eutectic gallium indium (EGaIn), a gallium alloy. The efficacy of pattern formation hinges on nozzle's design and internal geometry, which govern multiphase interaction. The interplay between EGaIn and polymer within the nozzle channels, regulated by variables such as traverse speed and material flow pressure, leads to periodic patterns. These patterns, when encapsulated within a dielectric polymer polyvinyl alcohol (PVA), exhibit an augmented inherent capacitance in capacitor assemblies. This discovery not only unveils the potential for cost-effective and highly sensitive capacitive pressure sensors but also underscores prospective applications of these novel patterns in precise motion detection, including heart rate monitoring, and comprehensive analysis of gait profiles. The amalgamation of advanced materials and intricate patterning techniques presents a transformative prospect in the domains of wearable sensing and comprehensive human motion analysis.

Multi-objective optimization and performance improvement of CD nozzle design parameters for cold spray coating process using RSM, ANN and GA

This study presents the multi-objective optimization of the convergent-divergent (CD) nozzle for the cold spray (CS) process and investigates the impact of five key nozzle design parameters. A 2D axisymmetric baseline nozzle was optimized through face central composite design (FCCD), computational fluid dynamics (CFD) simulations, response surface methodology (RSM), artificial neural networks (ANN), and genetic algorithms (GA). The nozzle performance in the CS process advances the manufacturing technologies by significantly optimizing the four response variables. Comparative analysis shows that RSM models (R² = 0.9893) were more accurate on average than ANN models (R² = 0.9848), although ANN provided a deeper understanding of complex interactions with an overall correlation coefficient of 0.99191. Sensitivity analysis suggested that increasing convergent length (Lc) increases particle velocity (PV) before it stabilizes while particle temperature (PT) decreases due to cooling effects. Divergent length (Ld) increases PV to an optimal range, but reduces PT, indicating energy loss. Smaller injector inner diameter (Did) enhances PV but reduces PT. Injector length (Li) increases PV to a certain limit, beyond which benefits stabilizes, and also increases surface pressure (SP). Expanding the exit diameter (De) increases PV, drops PT and heat flux (HF), and reduces SP, indicating decreased flow resistance. Optimization with RSM coupled with numerical simulation (RSM-DF) improved PV, PT, HF, and SP by 9.1 %, 4.4 %, 17.9 %, and 27.6 % respectively. Further optimization with a 5–6–4 ANN and GA (NSGA-II) improved PV by 5 %, PT by 5.4 %, HF by 15.7 %, and reduced SP by 20.9 %. Integrating CFD, RSM, ANN, and GA provides an effective approach for optimizing CD nozzle parameters.

Converging rainbow trapping silencers for broadband sound dissipation in a low-speed ducted flow

Rainbow trapping filters (RTFs) have been so far investigated to achieve broadband unit sound absorption in closed-end duct terminations. However, opened RTFs have been scarcely explored to realize broadband low-frequency dissipation of sound waves while being traversed by a low speed flow. To bridge the gap, we propose a RTF composed of coiled cavities whose inner radius follows a flow-compliant converging profile, referred to as a converging coiled CCRTF silencer. An effective medium approach and the transfer matrix method (TMM) showed the ability of such devices to produce slow sound, impedance matching and minute sound reflection and transmission over a wide bandwidth, confirmed by finite element simulations and scattering matrix measurements without flow. A causal analysis revealed that a large density of wall resonators enhances the silencer performance while its bandwidth is driven by the coiling factor, convergent contraction ratio and cavities axial growth. Particle swarm optimization of these parameters led to a sub-wavelength CCRTF silencer with near-unit dissipation over 3.5 octaves from 200 Hz upwards. Extended TMM and aeroacoustic measurements showed resilience of the CCRTF performance under upstream or downstream propagation conditions for outlet Mach numbers below 0.16, thereby opening up applications like the design of silent convergent nozzles.

Numerical investigation on the dependence of air consumption on injector parameters of the vortex spinning system for producing viscose yarns

Reducing air consumption has become the direction of improvement for vortex spinning technology which is most suitable for producing fasciated viscose yarns at high speed. In this article, computational fluid dynamics (CFD) models are established to study the effects of some injector parameters of the nozzle on the air consumption and yarn properties of vortex spinning for producing viscose yarns. Based on the model, the airflow pattern, including the static pressure and velocity characteristics as well as the mechanical energy distribution of the airflow in the nozzle are analyzed, while the air consumption and fiber motional characteristics during the yarn formation process are predicted. The experimental measurements of the air flow rate and yarn tenacity are also conducted to verify the numerical results. The results show that the air consumption increases monotonically as the diameter of injectors (d) increases from 0.4 to 0.6 mm, while it decreases as the radial distance from the injector axis to the nozzle axis ( R ¯ ) varies from 0 to 1. The yarn tenacity first increases as d increases from 0.4 to 0.5 mm, and then exhibits a decreasing trend as d further increases from 0.5 to 0.6 mm. Moreover, the yarn tenacity generally exhibits insignificant differences as R ¯ increases from 0 to 0.5, while it decreases more obviously as R ¯ increases from 0.5 to 1. This work can provide a reference for the design of the energy-efficient nozzle of vortex spinning for producing viscose yarns.

Investigation of Spray Characteristics for Detonability: A Study on Liquid Fuel Injector and Nozzle Design

Detonation engines are gaining prominence as next-generation propulsion systems that can significantly enhance the efficiency of existing engines. This study focuses on developing an injector utilizing liquid fuel and a gas oxidizer for application in detonation engines. In order to better understand the spray characteristics suitable for the pulse detonation engine (PDE) system, an injector was fabricated by varying the Venturi nozzle exit diameter ratio and the geometric features of the fuel injection hole. Analysis of high-speed camera images revealed that the Venturi nozzle exit diameter ratio plays a crucial role in determining the characteristics of air-assist or air-blast atomization. Under the conditions of an exit diameter ratio of Re/Ri = 1.0, the formation of a liquid film at the exit was observed, and it was identified that the film’s length is influenced by the geometric characteristics of the fuel injection hole. The effect of the fuel injection hole and Venturi nozzle exit diameter ratio on SMD was analyzed by using droplet diameter measurement. The derived empirical correlation indicates that the atomization mechanism varies depending on the Venturi nozzle exit diameter ratio, and it also affects the distribution of SMD. The characteristics of the proposed injector, its influence on SMD, and its velocity, provide essential groundwork and data for the design of detonation engines employing liquid fuel.

Effects of the nozzle structure and fluidized gas composition on the gas-particle two-phase jet characteristic in a powder fuel scramjet

The interaction between nozzle design and fluidization gas composition significantly influences the dynamics within a powder fuel scramjet's combustion chamber. To investigate this relationship, an experimental study utilized high-speed shadow imaging technology to explore the macroscopic aspects of powder fuel injection. The investigation examined various convergence angles, nozzle throat lengths, and fluidized gas compositions. Key findings include: During jet development, powder fuel initially concentrates near the axis, with non-convergence angle nozzles exhibiting longer concentrated distribution periods than convergence angle conditions. Decreasing nozzle convergence angles lead to increased penetration distance, frontal velocity, and radial diffusion distance during the initial stages of jet development. Additionally, stable jet shapes show larger divergence angles as nozzle convergence angle decreases, with the largest divergence angle observed at α=60°. In the initial 0–7 ms of jet development, the powder fuel jet demonstrates greater penetration distance and frontal velocity under certain conditions. Moreover, penetration distance and frontal velocity increase with throat length from 7 to 20 ms, accompanied by changes in divergence angles. Specifically, at a throat length (l) of 2 mm, the near-field divergence angle measures 46.50°, and the far-field divergence angle is 22.25°. Conversely, at l=8mm, the near-field divergence angle is 33.49°, and the far-field divergence angle is 23.21°. The fluidization gas composition minimally affects jet penetration distance and frontal velocity during the initial 0–3 ms. However, due to hydrogen's low density, hydrogen/powder fuel jets exhibit shorter distances and velocities compared to nitrogen/powder fuel jets. Hydrogen fluidization also results in larger divergence angles, particularly in the near field. These findings underscore the importance of nozzle design and fluidization gas composition in optimizing scramjet performance and efficiency.

Prediction of gas-solid nozzle performance based on CFD and response surface methodology

In this work, structural parameters and performance prediction of fan nozzles for powder spraying are investigated. Computational Fluid Dynamics (CFD) was used to simulate the working process of the grooved fan nozzle. A Box-Behnken experimental model was developed to analyze the effects of the structural parameters on the nozzle air flow stability and working performance, taking the nozzle structural parameter contraction angle (α), the ratio of outlet to inlet diameter (d/D), the ratio of outlet diameter to length (L2/d), and the half angle of the “V”– shaped groove (β). The air flow stability and working performance of nozzle were evaluated through coefficient of variation (Cv) and standard deviation (SD). Using multiple regression analysis, the prediction model of Cv and SD on the structural parameters is established. It was obtained that: with the increase of the diameter and length of the nozzle outlet, the spray angle of the nozzle decreases. As the “V”– shaped groove angle increases, the powder spray angle decreases. The effects of structural parameters on Cv are d/D, α, β, and L2/d in ascending order, and on SD are d/D, α, β, and L2/d in ascending order. In addition, the influence of the interaction of each structural parameter on Cv and SD was obtained. This study can provide a reference for the design and structural optimization of fan nozzles for powder spraying.

Additive manufacturing of scalable jet impingement and radial taper enhancements for improved flow boiling performance

Additive manufacturing (AM) offers a unique route to improve flow boiling heat transfer by enabling the fabrication of complex fluidic devices. In this study, two types of advanced jet impingement designs were additively manufactured and tested in subcooled flow boiling of DI water with 20 °C of subcooling. The first design was an in-line extended nozzle jet impingement manifold with nozzles off angle to the flow direction that extend towards the heated surface in order to decrease pressure drop and reduce viscous dissipation. The influence of jet velocity was explored and the optimal 3 nozzle design achieved a critical heat flux (CHF) of 191 W/cm2 and heat transfer coefficient (HTC) of 42.1 kW/m2K at a pressure drop of 3.4 kPa. This represents a 78% increase in CHF and 64% increase in HTC compared to open flow conditions. Following this, a second more complex design was created combining jet impingement, tapered flow paths, radial flow, and intricate fluidic routing to further improve heat transfer. This complex design would be extremely difficult to manufacture without additive techniques and resulted in a CHF of 375 W/cm2 and HTC of 74.2 W/m2K at a pressure drop of 3.5 kPa at a flow rate of 300 mL/min. This represented a 250% and 189% increase in CHF and HTC respectively over open channel flow conditions at a low pressure drop. These designs are easily scalable, and represent a new class of “on surface” flow boiling jet impingement enhancement techniques enabled through the use of additive manufacturing of polymeric materials.

Thermo-structural analysis of a dump nozzle for conducting hot liquid sodium

Liquid sodium is found to be an essential element in nuclear reactors for transferring enormous amount of heat between source and sink. Conducting hot liquid sodium through metal pipes is witnessed to be challenging owing to the huge thermomechanical stress involved during the process. The present research work aims at designing a dump nozzle for the safe transfer of hot liquid sodium (at 923 K) to a storage tank through SS316LN pipe. Numerically simulated results showed the development of huge thermal stress at the weld junction formed between pipes and storage tank, which is primarily due to the sudden increase in temperature. The newly proposed dump nozzle with reducer/baffle (connecting pipe with storage tank) is witnessed in reducing the sudden increase in temperature and henceforth, minimized the stress intensity of the weldment by 70 %. The fatigue-creep interaction diagrams are plotted for the weld and the reducer; the results showed that the induced stress values for the parts are well below the safety envelops for the given boundary conditions of liquid sodium flow velocity and temperature. The proposed dump nozzle design is hence validated for the safe handling of transferring liquid sodium to storage tank.

Increased outlet design of flat-fan nozzle improves octocopter unmanned aerial vehicle sprayer's efficiency

Increased interest in unmanned aerial vehicle (UAV) sprayers leads to identifying the factors affecting their efficiency. This study aimed to check and introduce a factor that has not been considered so far – the outlet design of a flat-fan nozzle. In a field experiment, spray drift potential and chemical weed control efficacy (sulfosulfuron against spontaneous barley) from an octocopter UAV sprayer was evaluated as a two-factor randomized complete block design including nozzle type (standard, anti-drift, and air induction) and nozzle outlet design (single, twin, and triplet-orifice). When averaged over nozzle outlet design, 22.9, 31.0, and 39.6% in-swath spray deposition and 66.0, 73.6, and 93.5% spontaneous barley control were obtained for standard, anti-drift, and air induction nozzles, respectively. Also, a similar trend from out-swath spray coverage was observed up to 8 m. In the standard, anti-drift, and air induction nozzles, an outlet design change from single-to triplet-orifice changed in-swath spray coverage by −30.8, +16.4, and +39.4% and herbicide efficacy by −27.1, +27.7, and +19.3%, respectively. The results showed that the outlet design of flat-fan nozzles had a significant interaction effect with the nozzle type. It was suitable with the anti-drift and air induction nozzles but unsuitable with the standard nozzle.

Computational Fluid Dynamics (CFD) Analysis of Bioprinting.

Regenerative medicine has evolved with the rise of tissue engineering due to advancements in healthcare and technology. In recent years, bioprinting has been an upcoming approach to traditional tissue engineering practices, through the fabrication of functional tissue by its layer-by-layer deposition process. This overcomes challenges such as irregular cell distribution and limited cell density, and it can potentially address organ shortages, increasing transplant options. Bioprinting fully functional organs is a long stretch but the advancement is rapidly growing due to its precision and compatibility with complex geometries. Computational Fluid Dynamics (CFD), a carestone of computer-aided engineering, has been instrumental in assisting bioprinting research and development by cutting costs and saving time. CFD optimizes bioprinting by testing parameters such as shear stress, diffusivity, and cell viability, reducing repetitive experiments and aiding in material selection and bioprinter nozzle design. This review discusses the current application of CFD in bioprinting and its potential to enhance the technology that can contribute to the evolution of regenerative medicine.

Numerical investigation of dynamic characteristics of dual throat nozzle and bypass dual throat nozzle in thrust vectoring starting process

The Bypass Dual Throat Nozzle (BDTN) is a novel fluidic Thrust Vectoring (TV) nozzle, it switches to TV state by opening the valve in the bypass. To greatly manipulate the BDTN, the dynamic characteristics in the TV starting process should be analyzed. This paper conducts numerical simulations to grasp the variation processes of performances and the flow field evolution of BDTN and Dual Throat Nozzle (DTN). The dynamic responses of TV starting in typical DTN models are investigated at first. Then, the TV starting processes of BDTN in different Nozzle Pressure Ratio (NPR) conditions are simulated, and the valve opening durations (T) are also considered. Before the expected TV direction is achieved in the DTN, the jet is deflected to the opposite direction at the beginning of the dynamic process, which is called the reverse TV phenomenon. However, this phenomenon disappears in the BDTN. The larger injection width of DTN intensifies unsteady oscillations, and the reverse TV phenomenon is strengthened. In the BDTN, T determines the delay degree of performance variations compared to the static results, which is called hysteresis effect. At NPR = 10, the hysteresis affects the final stable performance of BDTN. This study analyses the dynamic characteristics in DTN and BDTN, laying a foundation for further design of nozzles and control strategies.

Influence of thermochemical non-equilibrium effects on non-uniform entrance scramjet nozzle

The high Mach number scramjet nozzle flow has prominent non-uniform characteristics and high-temperature non-equilibrium effects. Thus, the thermochemical non-equilibrium gas model was developed for simulating flows in the non-uniform and uniform entrance of a Mach 10 hydrocarbon fuel scramjet nozzle. The results show that the non-uniform entrance has a higher non-uniform degree in the flow-field compared to the uniform entrance. Additionally, the expansion degree inside the nozzle is greater and the thermal non-equilibrium effects downstream of the nozzle exit are stronger. The non-uniform entrance condition has a more intense chemical reaction near the nozzle exit but has less impact on the flow parameters. For the nozzle performance, under the influence of the non-uniform entrance, the greater gas expansion degree inside the nozzle results in a lower pressure acting on the upper wall, and then the nozzle thrust decreases by 1.68%. Hence, the structural design and performance optimization of the high Mach number scramjet nozzle must consider entrance non-uniform characteristics and thermochemical non-equilibrium effects.

In vitro evaluation of intersubject variability in pediatric intranasal drug delivery using nasal spray suspension products

Evaluation of the regional intranasal delivery of locally acting drugs in children is challenging. Anatomical nasal airway replicas potentially can provide a robust pre-clinical tool to test the performance of devices and formulations. However, there is often a challenge in identifying the nasal geometries that can reasonably be indicative of in vivo regional mass distribution of administered drug. This in vitro study was designed to investigate the regional intranasal drug delivery in 20 children, 2–11 years old (50% 2–6 years old and 50% female), using two commercially available suspension nasal spray products with different nozzle designs, plume characteristics, and active pharmaceutical ingredients. High-resolution computed tomography scans of the sinonasal region of pediatric human subjects with healthy nasal airways, reviewed and scored by a head and neck surgeon, were used to develop 20 three-dimensional (3D) replicas of the nasal airways. The 3D replicas were segmented into the two regions: anterior and posterior to the internal nasal valve (INV). They were then rapid prototyped in high clarity rigid plastic (Accura ClearVue). Each side of the septum of the 20 subjects was examined separately, resulting in 40 singular nasal cavities. A nozzle-specific spray tip holder was designed for each case to ensure consistent administration (insertion length, sagittal angle, and coronal angle) in all replicates. The wide range of posterior drug delivery observed in the forty geometries indicated significant intersubject variability in pediatric intranasal drug delivery. Three nasal geometries representing low, medium, and high levels of drug delivery to the target region, posterior to the INV, were chosen from the 40 nasal cavities. Our vision is that these three nasal geometries can potentially be beneficial in determining whether performance differences between test and reference nasal spray products are present that may affect their bioequivalence in children. They also may be useful when applied in parallel with similar adult nasal geometries, previously developed following a similar procedure, to provide additional insights into pediatric nasal drug delivery with innovator products in children in lieu of extending clinical studies to include pediatric subjects.

Impacts of flash boiling plume interactions on atomization evaluated using two-dimensional optical slit nozzles

Flash boiling atomization is a promising approach for liquid fuel energy conversion purposes, especially for alternative fuels and zero-carbon fuels. However, the fundamental mechanisms of flash boiling atomization is quite different from typical sub-cooled atomization both in the primary breakup mechanisms and plume interference principles. This work aims to investigate the spray plume interaction impacts under flash boiling injection schemes. To reduce the complexity in handling the dense spray regime for practical spray injectors, two-dimensional slit nozzles created by quartz blocks and thin channels are employed. Divergent, straight, and converge nozzles are designed and examined to evaluate the impact of nozzle design under the same thermodynamic conditions. Nozzles with a 2D expansion cavity are also tested to further reduce the optical depth in the observation direction. Various optical diagnostics methods including backlit measurement, phase Doppler interferometry, and the optical flow method are used to investigate different characteristics of the resultant superheat flows from different perspective. The experimental investigations reveal the interference mechanism of the two-plume nozzle with the increment of fuel temperature, as well as its impacts on atomization efficiency from the perspective of droplet sizes.

Optimizing the design of a supersonic Planar Dual Bell Nozzle (PDBN)

Dual bell nozzles present a promising solution for maximizing propulsion efficiency at high altitudes, while also mitigating dangerous side loads at lower altitudes. Such nozzles are comprised of two distinct contours, with the first optimized for low altitude operation, and the second tailored for high altitude conditions. These contours are interconnected at an inflexion point. The present study focuses on optimizing the contour design of a planar dual bell nozzle. Leveraging the commercial ANSYS-Fluent software, we conducted an investigation into the influence of the inflection angle on the transition between the two operating modes, examined the flow behavior inside the nozzle, and assessed the impact of the inflection angle on the thrust coefficient.

Hydraulic Drilling Nozzle Design and Research

Hydraulic Drilling Nozzle Design and Research

JUSTIFICATION OF NOZZLE PARAMETERS OF JET-TYPE WASHING MACHINES FOR CLEANING AGRICULTURAL MACHINES AND UNITS

Agricultural machinery and equipment are exposed to significant contamination by various types of pollutants, some of which can be easily removed, while others require the use of special cleaning agents and machines. To remove these contaminants, a pressurized water jet is used, the biggest disadvantage of such devices is the significant water consumption, so the issue of intensifying the cleaning process of agricultural machinery using a limited amount of water is an important scientific task. Cleaning of agricultural machinery and units from contaminants is a complex technological operation, therefore, there is a need to develop and justify the parameters and operating modes of a high-tech washing device that would ensure high-quality removal of all types of contaminants with high efficiency, minimal water consumption and minimal labor costs. The analysis of cleaning technologies showed that water jet cleaning is the most promising for removing dirt from the surface of agricultural machines and units, the technology allows to increase the level of mechanical impact by using additional energy, which can be the energy of a rotating jet. The study examines the efficiency of cleaning washing plants from various contaminants. The main focus is on studying the impact of nozzle design on the quality and productivity of the washing process. Nozzles determine the shape of water jets and their velocity, determining the cleaning efficiency. The dagger and fan nozzles, their advantages and disadvantages are considered. Nozzle parameters such as orifice diameter, spray angle, and number of fan jets are investigated. It is shown that properly selected nozzle parameters play an important role in achieving the optimal cleaning effect and water saving. Factors such as flow coefficient, drag coefficient, and velocity coefficient that affect the performance and energy of the jet are outlined.

A compact 3D printed magnetically stirred tank reactor cascade coupled with a free impinging jet for continuous production of colloidal nanoparticles

Most colloidal nanoparticle production processes involve more than one step, such as particle nucleation, growth and stabilisation, that often take place at different time scales. Flow chemistry offers an attractive platform for nanoparticle synthesis, as it can provide excellent control of conditions for each individual step. In this work, a free impinging jet reactor (FIJR), known for its rapid mixing capability and fouling-proof operation, is followed by a cascade of 5 miniaturised (3 ml) continuous stirred tank reactors (mCSTR) that provides longer residence time and efficient temperature control for subsequent synthesis steps, while still being resistant to clogging due to active mixing. The small (0.1 mm) diameter nozzle design allowed the FIJR to provide excellent mixing even at relatively low flowrates (2 ml/min/jet). The mCSTR cascade was arranged in a vertical configuration (one tank on top of another), offering a compact design that is simple to use and requiring only one magnetic stirrer. It provided near-ideal macromixing with limited dead volumes and interconnections, as reflected by a residence time distribution comparable with the theoretical one for a CSTR cascade. Most parts of the reactor system were 3D printed with features that facilitated the assembly. The proposed FIJR design overcomes the accuracy limitations of 3D printing by combining it with micromilling to achieve one of the smallest FIJR reported and by allowing for rotation of the nozzles to easily resolve issues with jet alignment. The reactor system was employed for the synthesis of colloidal (∼10 nm size) silver nanoparticles via NaBH4 reduction of AgNO3, in a 0.06 g/day scale for 50 min continuous operation and (∼6 nm core size) iron oxide nanoparticles via co-precipitation of Fe3+/Fe2+, producing colloidally stable nanoparticles in a 16.1 g/day scale for over 2 h continuous operation.

Impact of open‐air processing on atmospheric pressure plasma deposition of poly(ethylene oxide) coatings for antifouling applications

AbstractAtmospheric pressure plasma deposition (APPD) of poly(ethylene oxide) (PEO)‐like antifouling coatings provides an attractive way to reduce biofouling for reliable biosensor operation. Cold atmospheric pressure plasma jets are designed to operate in open air. This paper demonstrates the impact of open‐air processing on the composition and properties of PEO‐like coatings by APPD with vinyl ether precursors. The open‐air environment inhibits polymerization as indicated by low deposition rates, oxygen incorporation in the coatings, and instability of the coatings in water. The composition and stability of the coatings improve by appropriate nozzle design and by deposition in an environment with lower air content. The resulting PEO‐like coatings are stable and antifouling for an antibody solution and inhibit adhesion of human fibroblast cells.