Nozzle Part Research Articles

Automatic detection of hidden defects and qualification of additively manufactured parts using X-ray computed tomography and computer vision

Additive manufacturing (AM) has the unique capability to produce parts with complex three-dimensional structures with features that are internal to the part and hidden from view. Such internal features are difficult to inspect and may have defects that affect the function of a part. X-ray computed tomography (CT) is one of the only methods for nondestructive inspection (NDI) of the interior of AM parts. This paper explores how machine learning (ML) methods can be used to analyze CT scans of AM parts to automatically identify the presence of defects in geometric features. We designed a nozzle part with internal three-dimensional (3D) channels and introduced five different synthetic defects whose presence could affect the nozzle performance. A resin-based AM process fabricated 155 nozzle parts that included both defect-free parts and parts with synthetic defects. CT scans were collected for each part and processed into 68,510 image cross sections. The extracted images were used to train an ML model based on the ResNet34 architecture. The model can automatically identify and classify defects in individual CT slice images with over 98% accuracy. High model accuracy is possible with training on as few as 30 parts. The research demonstrates the potential of ML methods to automatically identify hidden defects and qualify AM parts using X-ray CT scans.

Structure analysis of double comb about jet spinning machine based on CFD

PurposeAs a new type of spinning machine, the jet spinning machine absorbs the carding system of the rotating cup spinning series and the nozzle part of the jet spinning. This paper aims to intends to introduce the double carding structure currently studied by the rotating cup spinning into the jet spinning machine, and analyze the influence of the nozzle characteristic number on the flow field in the double carding structure to verify the advantages of the double carding structure.Design/methodology/approachThe simulation is used to evaluate the performance of single/double split jet spinning and nozzle feature number, verify the technical advantages of double split jet spinning and evaluate the influence of nozzle feature number on flow field. The influence of the nozzle characteristic number on the flow pattern in the four models is compared. The advantages and disadvantages of a conventional single comb and a double comb with a bypass channel on the longer side of the transport channel as an additional air supply channel are also evaluated.FindingsAt present, the double comb technology of rotary cup spinning is being studied at home and abroad to improve the spinning quality and improve the difficult problem of mixed yarn with large difference in processing fiber properties. At present, the jet spinning machine combines the advantages of rotary cup spinning and jet spinning, absorbing the comb system of rotary cup spinning series and the nozzle part of jet spinning. Therefore, it is found that the introduction of the double-split structure into the wool jet spinning has research value to improve the spinning quality.Originality/valueThe purpose of this paper is to refer to the previous research on the double comb structure in rotary spinning, and to apply the double comb structure in the new jet spinning machine to improve the spinning quality. The simulation is used to evaluate the performance of single/double split jet spinning and nozzle feature number, verify the technical advantages of double split jet spinning and evaluate the influence of nozzle feature number on flow field.

Hydroabrasive wear of jet pump nozzles

The measurements of hydroabrasive wear of the jet pumps nozzles, used on dredges operating on transferring pulp, are carried out. The measurement result is compared with the result of modelling the flow in the pump suction chamber near the nozzles. The modelling is carried out using the Fluent program complex as a part of the Ansys program; the pure water is being modelled in the suction pipe. This assumption is made taking into account that pulp contains approximately 10 percent by volume of sand, therefore the trajectories of sand particles movement coincide with the streamlines of water. The results of modeling have shown, that the angle of attack on the surface of nozzle nose part nearest to the pulpline outlet is close to zero, whereas the angles of attack on the surface of the nozzle nose part furthest from the pipeline outlet differ considerably from the zero and range from 20 to 50 degrees, that is the values at which the hydroabrasive wear increases severalfold compared to the angles close to zero. The results of modelling are confirmed by the examination of the worn nozzles. It is turned out that the nose part of the nozzles wears out along a circle unevenly, the part furthest from the pipeline outlet wears at higher rate, that leads to the bevel of the plane of the nozzle nose opening, the bevel angle reaches 20–25 degrees. The microhardness values of the nose part of the worn nozzle are also in agreement with the results of modelling. The measurements have shown, that the microhardness of the nose part of the worn nozzle is uneven along a circle, and the microhardness of the most worn side of the nozzle nose is least. This fact indicates that the different zones of the surface of the nozzle nose part differ from each other by the rigidity of stress state scheme in hydroabrasive attack. It can be used later in choosing the regime of laboratory tests on hydroabrasive wear.

Comprehensive microstructural and mechanical characterization of transient liquid phase bonded austenitic stainless steel by Ni–Cr–Si–B amorphous interlayer

In this research, along with the joining of the gas turbine fuel nozzle part from austenitic stainless steel 316L alloy with BNi-2 interlayer by the transient liquid phase bonding process, microstructure test, shear strength and tensile strength tests have been placed. Bonding at a temperature of 1080 °C and a holding time of 45 min has led to the completion of isothermal solidification in the bonding zone. Microstructural and phase investigations showed that austenitic stainless steel 316L undergoes phase transformation after exposure to temperature conditions and the δ ferrite phase is formed as separate areas due to the diffusion of the solid state of ferrite-forming elements, and the grains of the base metal are 32 μm have reached 43 μm, which has caused a decrease in the shear strength of the base metal from 362 MPa to 347 MPa. Despite the completion of isothermal solidification in the joint centerline due to the boron diffusion of the solid state into the base metal and achieving the maximum shear strength of the joint (402 MPa), two generations of boride deposits have been formed. The first-generation borides based on nickel-iron-chromium-molybdenum are formed during heating up to the bonding temperature, and the second-generation boride deposits are based on iron-chromium-molybdenum, which were deposited in situ during the isothermal solidification stage. The microhardness test confirms the uniform distribution of hardness in each of the bonding zones, which feedback was determined in the tensile strength test. The tensile strength of the bonded sample was 485 MPa, which is approximately 82 % of stainless steel 316L. In both shear and tensile tests, the presence of small dimples indicates the ductile failure of the joint samples in base metal.

Orthogonal analysis method for multi – Objective optimization of CO2 nozzle thermodynamic performance

In this study, the structural parameters of the converging diverging (CD) nozzle in a subcritical or supercritical CO2 cycle system were optimized by L16 (44) orthogonal design. The established model was used to analyse the effect of divergence length Ld, divergence angle θ, convergence angle α and throat diameter Dth on the nozzle thermodynamic performance, and further optimization of CD nozzle structural parameters was carried out using comprehensive evaluation coefficients and comprehensive scores. The results indicate that Ld is the primary factor, and while the effects of θ and Dth were inconsistent in different application scenarios, attention should be paid to the size parameters of the nozzle divergence part during design. For CD nozzles with supercritical inlet pressure, there is a linear relationship between Ld and exergy destruction, while for subcritical CD nozzles, the effect of Ld is reduced. For a CD nozzle used in subcritical or transcritical cycles, the outlet exergy and exergy efficiency of the modified nozzle could be increased by 16.4% and 16.2%. For supercritical nozzles used in the Brayton cycle, the optimized exergy destruction was relatively reduced by 37%. The mass flow rate of the nozzle before and after optimization was reduced, with a maximum decrease of 22.7%, which is beneficial for improving the entrainment ratio of the ejector. In addition, it was found that considering this in the modelling process would lead to conservative optimization results. These research results could provide a reference for the design of the CO2 nozzle or motive nozzle of ejector.

Development of Concrete Extrusion Nozzle for Producing Free-Form Concrete Panels and Extrusion Test

FCP (Free-form Concrete Panel) is used to easily realize the huge and complex curved surfaces of free-form buildings, and research on FCP manufacturing technology is being conducted. However, as the concrete was extruded manually into the manufactured mold, the precision of the FCP was lowered and errors occurred. Therefore, this study developed concrete extrusion equipment that includes a nozzle part, an open/close part, and a control part, according to the required performance derived from previous research analysis. The mixing ratio of concrete was selected at an appropriate value of W/C 38% and extruded uniformly with a width of 60 mm and a thickness of 22 mm. Depending on the opening/closing function, it was possible to open and close at the desired position. The concrete extrusion nozzle for FCP production is the basic equipment, and miniaturization and automation of the nozzle are required in the future. This is expected to contribute to the development of new free-form construction technology and equipment.

Experimental tests of submersible vane pumps

The technical task of creating new designs of submersible vane pumps is to maintain stable operating parameters and increase the productivity of the pumping station with periodic regeneration and sediment removal. The pumping well station contains an outer chamber and an inner chamber, in which a pumping unit is installed, and pipelines are connected to the lower and upper pools. In the structure under study, the upper parts of the outer and inner chambers are equipped with a sealed head, and the lower part of the outer chamber is equipped with a stopper. The side surface of the inner chamber is made of elastically deformable material. An elastic pipeline with an ejector at its end with curvilinear helical grooves on the inner surface of the nozzle part of the ejector is connected to the pipeline connected to the tailpipe, and water level meters are installed in the outer chamber. The technique of balance testing of new designs of submersible vane pumps was applied because the existing technology is insufficient for correct balance tests. Research methods involve the design of the impeller, which is rigidly mounted on the shaft. The methodology has been adjusted to apply to multistage pumps with different types of impellers. In the energy balance of this pump, the power losses due to friction in the individual axial support of the impeller are additionally determined. Experimental work was carried out, resulting in measurements of the hydrodynamic moment acting on the guide vane grate. Experimental work was carried out on a vertical stand with new pump impellers ETsV-10-120-40 and with a service life of 1 year. Parametric tests made it possible to determine the change in the external parameters of the pump depending on changes in its operating conditions and network characteristics.

New technological solutions for restoring the inner surface of hydraulic cylinders

Relevance. Agricultural machines widely use hydraulic cylinders for various auxiliary and working movements. Operation in harsh field conditions leads to the failure of the hydraulic cylinder mirror and, as a result, to the loss of force on the cylinder rod. The development of technological solutions for the restoration of the inner surface as a more appropriate solution in repair production is relevant.Methods. Studies of the heat flow using the “Fluke Ti32” thermal imager and ofthe influence of gas-dynamic spraying (GDS) modes on the adhesive and cohesive strength when using a new design of the nozzle part of the GDS equipment were carried out.Results. The suitability of usage of new nozzle design for GDS in order to restore the inner surface of the hydraulic cylinder body has been established. The elongated and curved nozzle for installations of the “Dimet” type practically does not change the temperature regime of spraying. The adhesive and cohesive strength of the coatings obtained with the new nozzle design is sufficient to operate under conditions characteristic of the inner surface of the hydraulic cylinder body.

Determination of optimum production parameters for 3D printers based on nozzle diameter

PurposeThe purpose of this paper is to determine the optimum nozzle diameter for parts production with polylactic acid using a three-dimensional printer. The additive manufacturing method used was fused filament fabrication.Design/methodology/approachDesigners and researchers have focused on the effects of these parameters on part strength. Additionally, production time is one of the disadvantages of this manufacturing method that researchers are trying to overcome. The production parameters that stand out at this point are nozzle diameter and layer thickness.FindingsAs a result of the study, it was determined that the increased nozzle diameter led to increased part strength. At the same time, layer thickness had the most significant effect on surface quality. The increased nozzle diameter and part density led to decreased production time. It was concluded that larger nozzle diameter and lower layer thickness should be used for parts with superior properties.Research limitations/implicationsThe experimental printing parameters used in the study were nozzle diameter (0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 mm), layer thickness (0.1, 0.2 and 0.3 mm) and printing orientation (0°, 45° and 90°). The effects of printing parameters on part strength, dimensional accuracy, surface quality and part density were analyzed experimentally.Originality/valueThe effects of several printing parameters have been examined in the literature. However, the effect of different nozzle diameters has been ignored. There are limited experimental studies that examine the effect of nozzle diameter on mechanical properties, surface roughness, dimensional quality and production time. In this regard, the results obtained from various nozzle diameters used in this study will significantly contribute to the literature.

Computational and experimental study of the influence of the shape of nozzle supersonic part on the flow structure in the gas-dynamic flow path of a model high-altitude test facility

Computational and experimental study of the influence of the shape of nozzle supersonic part on the flow structure in the gas-dynamic flow path of a model high-altitude test facility

Effects of nozzle divergent part on waterjet erosion characteristics for jet-type cloud cavitation

Effects of nozzle divergent part on waterjet erosion characteristics for jet-type cloud cavitation

Design and Analysis of Combustion Chamber for HAN Based Mono Propulsion System Thruster for Spacecraft Application

This paper presents a preliminary dimensional study of combustion chamber using Hydroxyl Ammonium Nitrate (HAN) propellants for spacecraft application. The combustion chamber consists of two parts namely thrust chamber and Convergent-Divergent (C-D) nozzle. The design for combustion chamber is very much important because the chemical energy in the propellant released within this closed volume i.e., thrust chamber and gets expanded through the C-D nozzle part. So the chamber must be designed to provide a necessary space for the propellants to react and release maximum available energy and also it should prevent the loss of energy in the form of heat. The C-D nozzle should be optimally designed to allow the maximum conversion of enthalpy into kinetic energy. So, the thrust chamber and C-D nozzle are designed in an optimum size for releasing the heat to convert maximum available heat energy from the combustion of HAN propellant into exhaust velocity for HAN based monopropellant thruster. In this work the combustion chamber i.e. thrust chamber and C-D nozzle are designed at 16 bar pressure to generate a thrust of 11 N. CFD analysis is done to show the pressure and temperature variation in the combustion chamber modeled for 11 N thrust and chamber pressure of 16 bar for spacecraft application. From the analysis result it is found that monopropellant engine with the propellant combination of HAN+ Methanol+ Ammonium Nitrate + Water is suitable for design of Attitude & Orbit Control System (AOCS) thrusters.

Influence of inlet vorticity and aspect ratio on axis-switching and mixing characteristics of heated rectangular jets

To investigate interactive characteristics between the inlet condition and axis-switching phenomenon, heated rectangular jets are numerically investigated for seven aspect ratios (AR = 1.0 − 6.0) with three jet temperatures of 300, 500, and 1000 K. The corresponding Reynolds number is 11,400 – 21,000. To examine the relative importance of ωθ and ωx on axis-switching, seven inlets are obtained by an inflow generator. For the flows of nozzle part, various geometry-driven and turbulence-driven vortices are observed. It is shown that the rotational directions of turbulence-driven vortices have the rotational direction hindering the axis-switching flow. By using the crossover location of the jet half-widths and the mixing length, the axis-switching condition depending on AR and jet temperature is explained. The crossover location is changed to the ωx-variation, which is approximately eight times as sensitive as the ωθ-variation. Based on the results of AR and temperature changes, the strong influence on axis-switching flow and mixing is confirmed for the ωx-change. Also, the heat transfer effect on mixing enhancement becomes strong for the weak axis-switching condition. As AR increases, the mixing performance decreases, but mixing enhancement of the axis-switching flow is confirmed for AR ≤ 4. Finally, to explain the ωx-variation related to the axis-switching mechanism, the ωx transport equations are analyzed by three terms of the Prandtl's first kind and the baroclinic torque. The roles of the vortex stretching and baroclinic torque terms are analyzed for the positive effect of the ωx-variation on the axis-switching phenomenon.

Investigation of Solid Propellant Rocket Motor Nozzle via CFD Simulation

The current work predicts the combustion characteristics of a solid rocket motor especially the flow in the nozzle part. The simulation work is done using computational fluids dynamic (CFD) software. The volume mesh was built in one quarter of the nozzle to reduce time for calculation. The same nozzle is also created with different mesh sizes for grid dependency check. All the rocket parameter is obtained from the theoretical design of rocket motor based on basic nozzle design. The simulation result in CFD is compared to the theoretical calculations and it shows that the modelling of rocket nozzle results shows good agreement with the theoretical ones. Parametric study on the nozzle was conducted. The results show that the best nozzle configuration for the current design is when the throat length is set to 1mm.

Investigation on hydrodynamic and formation of nano particle by RESS process: The numerical study

The particle formation by supercritical technology is an active research field. Rapid expansion of supercritical fluid (RESS) is a promising new technology for particle formation using supercritical fluids. In this study, numerical modeling of particle formation of TBTPP (5, 10, 15, 20-tetrakis (3, 5-bis (trifluoromethyl) phenyl) porphyrin) through RESS process is investigated. The RESS process contains two pre-expansion (nozzle part) and expansion vessel (supersonic free jet) parts. In the first section, mass, momentum and energy balances in addition to extended generalized Bender equation of state (egB-EoS) as accurate equation of state is used to calculate temperature, pressure, density and velocity of supercritical carbon dioxide (SC-CO2) based on mathematical modeling and computational fluid dynamics (CFD) simulation methods. Both models include friction in the nozzle and heat exchange in the expansion vessel and in the nozzle region. Using calculated pressure and temperature, the solubility of TBTPP in the supercritical CO2 is predicted by Peng-Robinson EoS with Kwak-Mansoori mixing rule and the results are compared with experimental data and a semi-empirical correlation. Supersaturation, homogenous nucleation and critical radius of TBTPP based on classical nucleation theory are calculated. The effect of pre-expansion temperature on supersaturation, nucleation and critical radius parameters is also studied. The results of hydrodynamic and particle formation modeling present the same trend as reported in the literature.

Determination of Axial Electric Field Distribution in Blown Arcs With Differential Method

DC switchgear using gas circuit breakers (CBs) in parallel to a LC-resonant path is used for decades already. This “passive oscillation” topology relies on negative damping of the oscillating current made possible by the fact that the voltage drop over the CB decreases with increasing current. This concept is cheap and reliable since it does not require any active components besides the mechanical breaker. However, the achievable breaking times and maximum interruptable current amplitude highly depend on the u(i) characteristic of the axially blown arc inside the breaker. Improvements to the breaking chamber could move the maximal breakable current to higher values and reduce the time to current zero. Analyzing which parameters influence the arc voltage is crucial for this optimization. Knowing which axial segments contribute how much to the total arc voltage enables a deeper understanding and possibilities to improve performance. Direct measurements of voltages inside the nozzle of a CB are not feasible; therefore, an indirect method was developed. The contact positions in a model CB were varied systematically, and by evaluating the u(i) curves of 13 different configurations, the voltage drop of eight segments of 2 cm length was calculated. It is shown that most of the voltage drops over the converging nozzle part, where gas density and acceleration is high. These segments also exhibit beneficial behavior with du/di being negative. The method was validated by comparing the extracted results with suitable direct measurements.

Research on the Acoustic-Structure Coupling Characteristics of a Piezoelectric Micro-Jet Used for Lubricating

The injection performance of the piezoelectric micro-jet is mainly determined by the acoustic characteristics created in the cavity by the vibration of the piezoelectric vibrator. As sensors are difficult to be placed into the cavity of the piezoelectric micro-jet, the inside acoustic characteristics are hard to be tested by experiments. Thus, an acoustic-structure coupling model is given, and simulation analyses are carried out in this paper to study a piezoelectric micro-jet used for lubricating. The suitable working frequency for getting better lubricating performance is obtained by the frequency response characteristics analyses. The driving mechanism is revealed by comparing with the injection results. The influences of excitations on the acoustic pressure at the nozzle part are analyzed, and the methods for adjusting the working performance are obtained. The acoustic structure coupling model and results are verified by comparing with the experiment results.

消・脱臭剤のノズル噴霧による臭気除去効果に関する基礎的研究 （その8）一流体ノズルを用いた下向き噴霧流性状の解析手法

消・脱臭剤のノズル噴霧による臭気除去効果に関する基礎的研究 （その8）一流体ノズルを用いた下向き噴霧流性状の解析手法

消・脱臭剤のノズル噴霧による臭気除去効果に関する基礎的研究 （その15）一流体ノズルからの弱酸性次亜塩素酸水溶液のミスト噴霧による消臭効果

消・脱臭剤のノズル噴霧による臭気除去効果に関する基礎的研究 （その15）一流体ノズルからの弱酸性次亜塩素酸水溶液のミスト噴霧による消臭効果

Design of a test facility for probe calibration

A possibility to easily calibrate probes for flow field measurements is always welcome. From this reason, a design of a test facility for probe calibration was made. The probes will be calibrated in a free jet of known properties, which is created by an exchangeable nozzle to cover a wide range of Mach numbers up to Mach 2. The most important is to create a homogeneous flow across the test section. This is accomplished by a precise design of the nozzles carried out by numerical tools. The convergent nozzle part is common for all subsonic flow regimes while the divergent part (forming a de Laval nozzle) is suited for a specific supersonic Mach number. These parts are designed using the method of characteristics. Numerical simulations performed by a CFD code show a feasibility and quality of the proposed test facility.