Multiple Nozzles Research Articles

A Comparative Analysis of Single Nozzle and Multiple Nozzles Arrangements for Syngas Combustion in Heavy Duty Gas Turbine

Heavy duty gas turbines are the core components in the integrated gasification combined cycle (IGCC) system. Different from the conventional fuel for gas turbine such as natural gas and light diesel, the combustible component acquired from the IGCC system is hydrogen-rich syngas fuel. It is important to modify the original gas turbine combustor or redesign a new combustor for syngas application since the fuel properties are featured with the wide range hydrogen and carbon monoxide mixture. First, one heavy duty gas turbine combustor which adopts natural gas and light diesel was selected as the original type. The redesign work mainly focused on the combustor head and nozzle arrangements. This paper investigated two feasible combustor arrangements for the syngas utilization including single nozzle and multiple nozzles. Numerical simulations are conducted to compare the flow field, temperature field, composition distributions, and overall performance of the two schemes. The obtained results show that the flow structure of the multiple nozzles scheme is better and the temperature distribution inside the combustor is more uniform, and the total pressure recovery is higher than the single nozzle scheme. Through the full scale test rig verification, the combustor redesign with multiple nozzles scheme is acceptable under middle and high pressure combustion test conditions. Besides, the numerical computations generally match with the experimental results.

Direct laser deposition of Ti-6Al-4V from elemental powder blends

Purpose This paper aims to achieve Ti-6Al-4V from Ti, Al and V elemental powder blends using direct laser deposition (DLD) and to understand the effects of laser transverse speed and laser power on the initial fabrication of deposit’s microstructure and Vickers hardness. Design/methodology/approach Two sets of powder blends with different weight percentage ratio for three elemental powder were used during DLD process. Five experiments with different processing parameters were performed to evaluate how microstructure and Vickers hardness change with laser power and laser transverse speed. Energy dispersive X-ray spectroscopy, optical microscopy and Vickers hardness test were used to analyze deposits’ properties. Findings This paper reveals that significant variance of elemental powder’s size and density would cause lack of weight percentage of certain elements in final part and using multiple coaxial powder nozzles design would be a solution. Also, higher laser power or slower laser transverse speed tend to benefit the formation of finer microstructures and increase Vickers hardness. Originality/value This paper demonstrates a new method to fabricate Ti-6Al-4V and gives out a possible weight percentage ratio 87:7:6 for Ti:Al:V at powder blends during DLD process. The relationship between microstructure and Vickers hardness with laser power and laser transverse speed would provide valuable reference for people working on tailoring material properties using elemental powder method.

Pressure, droplet size classification, and nozzle arrangement effects on coverage and droplet number density using air-inclusion dual fan nozzles for pesticide applications

Spray applications are most effective when they cover the greatest per unit area, improving target pest control. In order to optimize spray applications, nozzle companies have developed new designs that seek to provide the greatest and most uniform coverage per target unit area. While dual fan nozzles have been examined against single fan nozzles in several studies, there has not been a comprehensive comparison of multiple nominal flow rate and multiple dual fan nozzle types. This study sought to examine pressure, droplet size classification, and nozzle arrangement effects on droplet number density on horizontal artificial collectors using a fixed application rate. The relationship between coverage and nozzle type was significant (P < 0.001) as was the relationship between coverage and pressure (P < 0.001). The 207 kPa pressure resulted in the highest coverage for every nozzle type except the alternating TADFs (ATADF)s. The GAT 11003 resulted in the highest coverage overall with 39.6% at the 207 kPa pressure, followed by the TADF 11005 and TADF 11003 at 38.6% and 38.3% coverage respectively. The effect of pressure was significant for the droplet number density (P < 0.001) as was the effect on droplet number density from nozzle type (P < 0.001). The 414 kPa pressure resulted in the highest droplet number density for all nozzle types except the AITTJ 11003 and the MDD 11004. The GAT 11003 and GAT 11004 produced the highest overall droplet number densities with 73.0 and 72.6 droplets cm2 at the 414 kPa pressure. The GAT 11003 had the greatest droplet number density at every pressure. Nozzle arrangement has a significant effect on spray coverage with asymmetric dual fan nozzles, and it would be recommended to alternate these nozzles on a spray boom to increase coverage especially at higher application speeds. Results from this study show that an applicator can select a coarser droplet size classification without observable loss in coverage, while greatly reducing the drift potential of the application.

Simultaneous Boiling Visualization and Heat Transfer Measurement of Two Adjacent Water Impinging Jets

The effect of jet-to-jet distance of two adjacent jets on boiling heat transfer was investigated by a simultaneous boiling visualization and heat transfer measurement. The hydrodynamics of two adjacent jets were visualized by the high-speed imaging and the 4K camera on unheated surface. The surface temperature of the hot steel plate was estimated by formulating 2-D inverse heat conduction, which was measured through the flat-plate heat flux gauge. The jet Reynolds number was fixed at Re = 17,000 and the jet-to-jet distance of two adjacent jets was set to the three different jet-to-jet distances (p/d = 10, 20 and 30). The wall jet flow interference between two adjacent impinging jets forms a vertical fountain at its boundary. The more scattered water droplets are observed from the fountain due to the higher intensity at the p/d = 10. The flow interaction becomes to reduce its momentum as increasing the p/d. The boiling visualization shows which boiling mode starts to occur and turns to be disappeared from film boiling to nucleate boiling on the hot surface. The measured surface temperature has a good agreement with the corresponding boiling visualization. The closer jet distance (lower p/d) shows the rapid temperature gradient along the interaction, which provides much higher cooling rate in a multiple jet nozzle when designing an intensive quenching device.

PCB assembly optimization in a single gantry high-speed rotary-head collect-and-place machine

This paper presents an optimization study of the single gantry high-speed rotary-head collect-and-place (CAP) surface mount device (SMD) machine. The rotary-head gantry-type CAP machine has the advantage of high flexibility and speed, which is widely used in the PCB assembly of smart phones, tablets, laptops, and monitors. However, the pick-and-place process in SMD machines is the most time-consuming stage that determines the cycle time of a PCB assembly lines. This single gantry optimization problem can be decomposed into nozzle assignment, feeder assignment, and component pick-and-place sequence problems. Because they are highly interrelated to each other, an integer programming model is developed to solve them simultaneously. Based on the operational characteristics of high-speed machines, an adaptive nearest neighbor tabu search (ANNTS) is proposed to integrate the solution processes of feeder assignment, pick-and-place sequence, and multiple nozzle types assignment. Compared to CPLEX results, the ANNTS finds all optimal solutions of 14 randomly generated small-sized data sets. Another 13 industrial data sets are used to test the variants of the ANNTS, which include different initial solutions and search heuristics. Compared to the large clusters of operations (LCO) heuristic (Kulak et al. Int J Prod Res 45(17): 3949–3969, 2007), the ANNTS yields a 23.32 % distance saving on average for the single nozzle type problems. The ANNTS improves the productivity by 5.79 % on average, compared to the industrial package results.

Continuous nanofiber coated hybrid yarn produced by multi-nozzle air jet electrospinning

Multi-nozzle air-jet electrospinning was used to produce continuous viscose filament/polyvinylidenefluoride (PVDF) nanofiber hybrid yarns. The production of PVDF nanofibers using this method was based on the principle that the rupture of bubbles results in multiple jet flows. Nanofibers ejected from multiple nozzles were gathered and bundled by conjugate electrospinning and were then twisted on the surface of a filament yarn through the rotation of a metal funnel. The structures and properties of the hybrid yarn were characterized, and spinning mechanism of this novel method was analyzed. The experimental results obtained in this study showed that PVDF nanofibers were perfectly coated on the filament yarn surface with a good orientation and displayed uniform twist distribution with a twist angle of 24.3°, as well as PVDF nanofibers integrated with the core yarn well. After coating with twisted PVDF nanofibers, the mechanical properties of the yarn improved significantly. The stress and strain of the yarn at break increased from 19.39 MPa and 15.83% to 30.82 MPa and 19.81%, respectively. In addition, the hybrid yarn contact angle reached 150° after coating with the twisted PVDF nanofibers, indicating a transformation of the yarn from hydrophilic to hydrophobic. The nanofiber-coated hybrid yarn produced herein can possibly be used as a self-cleaning fabric.

Agglomeration in counter-current spray drying towers. Part B: Interaction between multiple spraying levels

A new experimental method is developed here to investigate agglomeration in spray drying towers operating with multiple nozzles. It allows studying independently the contribution of each spray to the product and obtaining a valuable insight into the agglomeration processes. The paper studies a two level swirl counter-current dryer of detergent in a full-scale production system. It shows that operation with two nozzle levels increases the energy efficiency compared to the use of single sprays, but in turn promotes both agglomeration and elutriation of powder from the top of the dryer. The product size distribution becomes bi-modal and the composition and porosity of the product more heterogeneous due to the different thermal histories experienced by droplets from each spray. The method described here controls the air temperature and humidity nearby the nozzles to quantify the agglomerates resulting from particle contacts within each individual spray or from their interaction. Particle agglomeration is shown to be suppressed at the bottom of the dryer where the heat transfer rates are highest and promoted at the top spray, which originates a second coarse mode in the size distribution. Both levels do not operate independently; the powder elutriated upwards from the bottom nozzle is captured entirely by the top spray when it is centrally located. By isolating the independent impact of each nozzle in a dryer, the method provides powerful data to correlate the agglomeration behaviour with local process conditions, and so facilitate the development and validation of spray dryer models.

Parametric study of flow field and mixing characteristics of outwardly injected jets into a crossflow in a cylindrical chamber

Flow field and mixing characteristics of coolant radial jets injected radially from multiple nozzles rows of centreline distributer into a heated non-reacting crossflow in a cylindrical chamber is numerically investigated. The study simulates the process of air jets injection in the combustion chambers of gas turbines through discrete holes. Three-dimensional model using ANSYS-FLUENT 14.5 CFD package is used. The effects of jet-mixing ratio, nozzles diameter, distributer diameter, number of nozzles rows, number of nozzles per row on the penetration depth and mixing quality through chamber cross section are parametrically studied. The results are validated with the available experimental data and good agreement are obtained. The results showed that nozzle diameter, distributer diameter and jet-mixing ratio have effects on the penetration depth and the mixing quality compared to the effects of the number of nozzles per row and the number of nozzles rows. The effects are remarkable at high mixing ratio. The integral mixing quality along the chamber cross section increased with increasing mixing ratio, nozzles diameters, number of nozzles per row and number of nozzles rows. Dimensionless correlations for predicting the penetration depth and mixing quality in terms of the controlling parameters are developed.

Experimental Investigation of High-temperature Steel Plate Cooled by Multiple Nozzle Arrays

Experimental Investigation of High-temperature Steel Plate Cooled by Multiple Nozzle Arrays

다이케스팅 이형재 분사 로봇시스템의 터빈 모듈 설계에 관한 연구

ABSTRACT Cleaning by injecting dry ice and water is a generally adopted trend these days to clean molds (injection, diecasting foundry, press, rubber mold, etc). This cleaning method is performed manually, or by installing multiple high pressure spray nozzles. We have manufactured a turbine cleaning module device that is able to clean diecasting modules at any position and angle in the space by mounting an articulated robot instead of the existing pipe type injection nozzle, to minimize lead time and enhance working yield of the cleaning process. In this paper, we analyzed process factors that are required to design the turbine module by reviewing number of revolution, and results according to different blade angles and thicknesses of the mold release injection turbine module, using computational fiuid dynamics (CFD).Key Words : Flow Analysis( ), Turbine Module유동해석 ( ), Die Casting Mold터빈 모듈 (다이케스팅 금형), Nozzle( ), Release Injection Robot System노즐 (이형재 분사 로봇 시스템) # Corresponding Author : sdchoi@kumoh.ac.kr Tel: +82-54-478-7396, Fax: +82-54-478-7319

The Influence of Nozzle Type on the Coverage Degree when Performing Phytosanitary Treatments

Effectiveness of phytosanitary treatments is greatly influenced by the way how droplets are distributed on the plant, the coverage of all plant parts, regardless of their position (horizontal, vertical, inclined). Coverage has greater significance mostly using contact substances and can be modified by way of nozzle spraying, their droplet size and direction to the target surface.In order to improve the coverage degree, even using low quantities of active substances per hectare, the nozzles manufacturers developed a special nozzle with a double jet. This nozzle can have a symmetric or asymmetric jet. This way the plants are better covered and the coverage degree is improved.The multiple nozzles type trials attended showed that the coverage degree is not mostly influenced horizontally by the nozzle type. In vertical plane nozzle type is a decisive factor for increasing the coverage degree.e coverage degree is not mostly influenced horizontally by the nozzle type. In vertical plane nozzle type is a decisive factor for increasing the coverage degree.

Experimental Identification of Heating Process from Hyperthermic Intraperitoneal Chemotherapy (HIPEC) Equipment

Peritoneal Carcinomatosis (PC) carries a worse prognosis than other sites of systemic metastases. The combination of complete cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) is on the verge of becoming the gold-standard treatment of PC, when feasible. In order to develop a HIPEC equipment, with complex inflow distribution system having multiple nozzles and a multipoint temperature measurement system, model based techniques will be used by the authors in order to design heating and flow controllers. Thus a functional model is needed for the concerned process such that the simulated model and the behavior of the real system coincide. This paper presents the experimental identification of the heater used on each of the flow channels that result in a transfer function model for the heating process. Also the model for the temperature sensor is obtained

Influence of noncondensible gas on flowing characteristics of multiple nozzle oil jet pump for lubrication system in steam turbine

The full cavitation model introduced by Singhal et al. was partly improved based on experimental results. The improved cavitation model is used to simulate cavitating flow in multiple nozzle oil jet pump for lubrication system in steam turbine. The influence of noncondensible gas on flowing characteristics of multiple nozzle oil jet pump was studied with noncondensible gas content in the range of 0.01–500 ppm. Results show that noncondensible gas has little influence on nonchoking flow while imminent choking flow and deep choking flow are greatly affected. With the increase of noncondensible gas, multiple nozzle oil jet pump enters choking flow earlier. The maximum suction flow rate per unit throat area of multiple nozzle oil jet pump remains constant with varying pressure ratios and area ratios under choking flow, which is only determined by the noncondensible gas content. It is suggested that the maximum suction flow rate per unit throat area is used for the prediction of choking flow in multiple nozzle oil jet pump. This study also provides qualitative criteria for the upper limit of water content in lubrication oil, which avoids multiple nozzle oil jet pump working under choking flow.

A Facile and Fast Gelation Process to Prepare Highly Spherical Millimeter‐Sized Silica Aerogel Beads

Millimeter‐sized silica aerogel beads were successfully prepared by a facile fast gelation process, in which silica sol beads were generated by extruding preformed silica sol through multiple nozzles into oil phase and then transformed into silica alcogel beads, followed by supercritical drying. The transition process from the silica sol to the silica alcogel beads was finished at a 97.6% conversion rate. The resultant silica aerogel beads have an average diameter of ~1.5 mm with a good sphericity, and an average pore size of ~12 nm with topical porous three‐dimensional network structures.

Tomographic imaging of nonsymmetric multicomponent tailored supersonic flows from structured gas nozzles.

We report experimental results on the production and characterization of asymmetric and composite supersonic gas flows, created by merging independently controllable flows from multiple nozzles. We demonstrate that the spatial profiles are adjustable over a large range of parameters, including gas density, density gradient, and atomic composition. The profiles were precisely characterized using three-dimensional tomography. The creation and measurement of complex gas flows is relevant to numerous applications, ranging from laser-produced plasmas to rocket thrusters.

Addressable multi-nozzle electrohydrodynamic jet printing with high consistency by multi-level voltage method

It is critical and challenging to achieve the individual jetting ability and high consistency in multi-nozzle electrohydrodynamic jet printing (E-jet printing). We proposed multi-level voltage method (MVM) to implement the addressable E-jet printing using multiple parallel nozzles with high consistency. The fabricated multi-nozzle printhead for MVM consists of three parts: PMMA holder, stainless steel capillaries (27G, outer diameter 400 μm) and FR-4 extractor layer. The key of MVM is to control the maximum meniscus electric field on each nozzle. The individual jetting control can be implemented when the rings under the jetting nozzles are 0 kV and the other rings are 0.5 kV. The onset electric field for each nozzle is ∼3.4 kV/mm by numerical simulation. Furthermore, a series of printing experiments are performed to show the advantage of MVM in printing consistency than the “one-voltage method” and “improved E-jet method”, by combination with finite element analyses. The good dimension consistency (274μm, 276μm, 280μm) and position consistency of the droplet array on the hydrophobic Si substrate verified the enhancements. It shows that MVM is an effective technique to implement the addressable E-jet printing with multiple parallel nozzles in high consistency.

Entrainment of air into an infrared suppression (IRS) device using circular and non-circular multiple nozzles

The present investigation predicts the mass entrainment into an IRS device which is used in naval or merchant ships. A high velocity jet emanating from the nozzle exit entrains ambient air to cool the hot combustion products of the gas turbines. Experiments have been carried out on a laboratory scale IRS device to measure the entrainment ratio. An optimum funnel overlap height (Hoverlap/Deq,nz=0) has been found out from the experiments which shows the highest mass suction rate at that overlap height. Moreover, the entrainment is observed to increase with the inlet mass flow rate of the nozzle. For a full scale IRS device, the conservation equations for mass, momentum and turbulent kinetic energy as well as its dissipation rate are solved using finite volume techniques in a three-dimensional computational domain by employing eddy viscosity based k–ɛ turbulence model with standard wall function. The parameters such as the nozzle aspect ratio (AR), geometrical shape of the nozzles, pitch circle diameter (PCD) and multiple nozzles affect the entrainment ratio significantly. With five triangular nozzles (AR=1), the entrainment rate is enhanced by 15.7% as compared to a single triangular nozzle (AR=1).

전산유체해석(CFD) 모의를 이용한 다공형 스크류 노즐 입수관이 적용된 물탱크 내부의 사류구역 최소화에 대한 유동특성

전산유체해석(CFD) 모의를 이용한 다공형 스크류 노즐 입수관이 적용된 물탱크 내부의 사류구역 최소화에 대한 유동특성

Thermal Performance Analysis of Jet Impingement with Effusion Scheme

The present work investigates the thermal performance of a copper-based coupled impingement-effusion heat sink. A three-dimensional numerical analysis was executed for steady state, incompressible laminar, flow and conjugate heat transfer. A constant heat flux of 100W/cm2 was applied at the base of copper substrate while on the other side a heat sink model was designed. The jet plate consists of multiple impingement jet nozzles and each jet nozzle was surrounded by six effusion holes, computational domain was defined by applying symmetric boundary conditions. The effects of the design parameters such as jet diameter, effusion-hole diameter, stand-off and jet-to-effusionpitch were investigated. The analysis was carried out at a low Reynolds number of 200 to prevail laminar flow conditions. The maximum temperature rise, total pressure drop, area-averaged heat transfer coefficient, thermal resistance and pumping power were discussed with various design variables e.g., the ratio of the pitch-to-jet diameter, standoff-to-jet diameter and area ratio of jet-to-effusion hole. The design with higher standoff-to-jet diameter ratio offers lower overall thermal resistance while design with lower standoff-to-jet diameter ratios offer lower pressure drop penalty. Higher heat transfer was associated with lower pitch-to-jet diameter and higher standoff-to-jet diameter ratio. The functional relationship between the overall thermal resistance and the pumping power was studied, which presents the optimal front within the design space explored in the present study.

Effect of Injector Nozzle Design on Spray Characteristics for Hydrogen Direct Injection Engine Conditions

Hydrogen has a unique flammability property compared to other fuels. Previous researches proved that direct injection is the most suitable method for this particular fuel. This research aims to study the effect of injector nozzle geometry on mixture and internal combustion efficiency in four stroke automotive engine which operates using hydrogen fuel. The research will concentrate on two aspects, namely the inflow and outflow profile of the injector nozzle. For each flow profile, the effect of geometrical design of the nozzle on the parameter such as flow velocity, fuel penetration distance, average mass fuel consumption and diffusion will be studied in detail. In this study, numerical simulation analysis was done by using the computing fluid dynamics (CFD) software, Star-CCM+. Models comprise of multiple orifice nozzle geometry with single angle orifice and double angle orifice was developed with CAD software. A suitable design for a better mixing nozzle would then be determined. Nozzle which possesses a high number of orifice and a smaller diameter will result in a higher flow velocity in the cavity nozzle channel. Geometry of nozzle with different angle of orifice was found to be the most suitable due to the low flow penetration distance and fuel consumption as well as combustion enhancement by the diffusion rate.