Nozzle Distance Research Articles

Influence of global and local process gas shielding on surface topography in laser micro polishing (LμP) of stainless steel 410

Laser micro polishing (LμP) is a new laser-based material processing method that has a high potential to overcome common disadvantages of traditional polishing techniques. A special challenge in LμP is the processing of large areas since processing in a process gas atmosphere is deemed necessary to avoid undesired oxidation and minimize surface roughness. Therefore, a new process strategy for LμP on stainless steel AISI 410 was investigated in which a gas nozzle was used to create a local process gas shielding and therefore to significantly increase the field of maximal processing. Using a Nd:YAG high power Q-switch laser, we demonstrated that local process gas shielding is feasible for LμP in terms of avoidance of surface defects and achieved micro-roughness. In addition, a wide process window in terms of nozzle distances and gas flow exists for LμP. The resulting surfaces are highly reproducible in terms of surface roughness. Besides Argon, Nitrogen is another process gas that is highly suitable for LμP of AISI 410. The use of Nitrogen might therefore significantly lower future production costs in LμP. Finally, spatially resolved LμP was explicitly demonstrated on a textured press plate.

Investigating the effect of process parameters on the mechanical properties and temperature distribution in fiber laser welding of AISI304 and AISI 420 sheet using response surface methodology

Fiber laser welding of austenitic and ferritic stainless steel was performed based on response surface methodology to systemically analyze the effect of process parameters on the weld characterizations. The laser welding input parameters were selected (laser power, welding speed and nozzle stand of distance) while the tensile strength of the joint and temperature near the molten pool were considered as the main responses. Variation of nozzle distance about 5 mm had less effect on the temperature domain near the molten pool and weld tensile strength. Increasing the nozzle distance and moving the focal point position to the upper surface of the sheet surface led to the notable improvement of the tensile strength about 20 percent. In other words, transition of the focal point thorough the material thickness clearly reduced the joint strength due to creating more volume of martensitic micro-structure and finally cracking during the tensile test from HAZ region of ferritic steel. The interaction of the laser power and welding speed had noticeable impact on the molten pool temperature. Evidently, the rate of temperature reduction due to an increased welding speed is greater at higher laser power. Among the investigated parameters, the welding speed had the highest effects on the tensile strength of the joint. Increasing the laser power from 300 to 360 W raised the tensile strength about 20%. Interaction of the laser power and welding speed resulted in about 300 °C of the temperature reduction due to an increased welding speed at higher laser power of 395 W variation of nozzle distance at different lase power levels less effect about 5 percent in comparison to the welding speed versus nozzle distance although the similar trend was observed for both of them.

Experimental and numerical investigation on temperature field and tailored mechanical properties distribution of 22MnB5 steel in spray quenching process

Abstract Functional gradient high-strength steel structures on the basis of a novel tailored spray quenching process can achieve an excellent crashworthiness and weight reduction, which own a promising future in advanced automotive and mechanical engineering. This paper focuses on the temperature distributions and mechanical properties characteristics of high strength 22MnB5 steel under complex spray jetting conditions. A spray density-based physical modeling method is simplified to describe the spray flow field and the water film evolution on the hot 22MnB5 surface during the spray quenching process. Fluid characteristics of spray jetting with single/twin nozzles and corresponding heat transfer intensity are systematically investigated by self-developed experimental scenarios. The results reveal that the fluid-solid heat transfer coefficient (IHTC) is dependent on the spray-quenching temperature distribution, which owns an intense correlation between post-quenched mechanical property and the jetting parameters involving the spray jetting pressure (SJP), the spray jetting height (SJH), the nozzle distance (ND), and initial quenching temperature (IQT). The average cooling rate under the single/twin nozzles jetting conditions can reached as 28.5–170.5 °C/s and 36.84–137.42 °C/s, corresponding to the peak IHTCs are 10.11–49.47 kW/(m2 K) and 9.69–44.76 kW/(m2 K), respectively. The hardness firstly increases and then decreases from the central point/zone to the edge along the radial direction after the spray quenching process. The largest radial hardness after the single/double nozzles spray quenching can be up to 50.21 % and 31.58 % larger than the lowest value, respectively. Moreover, the in-plane temperature field and corresponding post-quenched mechanical properties are further numerically predicted by introducing into the time-dependent IHTC and coupling with the CFD and Johnson-Mehl-Avrami (JMA) modeling. Finally, a validation work of U-type specimen was conducted to show the spray quenching technology owns a prospective future for gaining more complex-shaped parts with tailored mechanical properties.

Influence of Shot Peening on Surface Characteristics of Case Hardened SAE9310 Gear Material

The shot peening is the cold working process by which the compressive residual stresses are induced in the component, and that increases surface hardness, which can be helpful to avoid the fatigue failure of the component. Shot peening process is using to improve the fatigue life of the automobile and aerospace components. Effectiveness of the shot peening in surface characteristics can be measured by the Almen Intensity, Surface hardness and Surface roughness. The impact of shot peening on case-hardened differential bevel gear is defined in this study. In the shot peening process, the surface of the gear rammed by the small hardened cut wire shots with high velocity and overlapping indentations are created on the gear surface. Hence, thecharacteristics of surface of the gear can be greatly improved by shot peening. For bevel gears, bending fatigue crack is the major failure mode. This study is discussed to enhance the mechanical and surface properties of SAE9310 bevel gear by using the shot peening process. The optimization of shot peening process is done by including multi-performance characteristics i.e. Intensity, Surface hardness and surface roughness of the bevel gear. The analysis includes air pressure, nozzle distance, shot flow rate, exposure time as process parameters. The main objective of this study to decide the optimized shot peening process parameters for required performance characteristics and most influencing factors on surface layer characteristics. The experiments have been conducted using Taguchi’s L9 orthogonal array design techniques.

Design and Fabrication of Abrasive Jet Machining Systems

ABRASIVE JET MACHINE presents the working of machining and removing materials from the brittle and heat sensitive materials by the application of high speed stream of abrasive particles carried by air through the nozzle. In particular drilling of holes of minimum diameter and maximum depth is also possible in this machine with greater accuracy and surface finish. Since no heat is induced while machining the surface, the workplace is not subjected to thermal shocks. Tumbling machining apparatus is used for determining the material removal rate (MRR) for materials like glass, ceramics and aluminium sheet by varying the parameters like pressure, nozzle tip distance (NTD), type of abrasive and its flow rate. In this project we have designed and fabricated the tumbling machining apparatus for removing unwanted material, drilling holes and cutting glass, ceramic plates and aluminium sheet.

Influence of process parameters on dimensional accuracy of machined Titanium (Ti-6Al-4V) alloy in Laser Beam Machining Process

The process enhancement plays a vital role in the modern machining techniques during machining of newer materials such as titanium alloys. In the present work, a research endeavor was made to examine the effects of process parameters in laser beam machining process while drilling holes over Titanium (Ti-6Al-4V) alloy under Taguchi approach of experiments. Nozzle distance, power, focal length and gas pressure were chosen as the input process parameters to assess the dimensional accuracy quality measures such as roundness and ovality in laser beam machining process. It was found that power has the most significant impact on determining the dimensional accuracy. 1.2 mm (ND), 2 mm (L), 4 bar (GP) and 2 kW (J) has been chosen as optimal process parameters combination for obtaining better dimensional accuracy among the selected process parameters. It was also observed that the machinability could be highly influenced with lower peak power.

Pestisit Uygulamaları İçin Optimize Edilmiş Koşullarda Sprey Karakteristiklerinin Belirlenmesi

Agriculture is a large and serious sector developing on a global basis. An important research subject in agriculture is the pesticide applications performed by spraying method. One of the objectives of spray application technologies is to provide using at the recommended dosage of pesticides at the right time by using the appropriate application techniques in order to reduce the level of pest or disease factors at crop production. In this study, the effects of flow parameters on droplet diameter of single hollow-cone nozzle used on conventional sprayers were investigated. For this purpose, three different nozzle-surface distances (70 cm, 85 cm, 100 cm), three different operational pressure (6 bar, 8 bar, 10 bar) and three different nozzle orifice diameters were determined as flow parameters under conditions of constant speed and spray angle. The experiments were carried out in duplicate at different times. After spray application, the droplet spot images obtained from the water sensitive paper surfaces were processed and the volumetric diameter and homogeneity values ​​were determined. In order to examine the effect of the flow parameters on droplet diameter, the charts were drawn and the variations were interpreted. In general, the characteristic droplet diameters were decreased and the homogeneity coefficient increased on the conditions of the same nozzle orifice diameter and spray distance as the operational pressure increased. Comparing nozzle orifice diameters for the same operational pressure and spraying distance, it was observed that the droplet diameter increased for the nozzles with large orifice diameter and the homogeneity value deteriorated.

Effect of printing parameters on interlayer bond strength of 3D printed limestone-calcined clay-based cementitious materials: An experimental and numerical study

For a single batch material, time intervals and nozzle standoff distances between two subsequent layers are two critical printing parameters that influence the mechanical performance of the printed concrete. This paper presents an experimental and numerical study to investigate the impacts of these printing parameters on the interlayer bond strength of the 3D printed limestone and calcined clay-based cementitious materials. All samples were manufactured by a lab-scale 3D printer equipped with a hybrid back- and down-flow nozzle (rectangular opening). The uniaxial tensile test was employed to quantify the interface adhesion of printed specimens. Moreover, the greyscale value image of microstructure, as well as the air void content and distribution of the printed specimens were acquired by X-ray computed tomography and characterized by image analysis. The experimental results showed that extending the time interval between construction of two layers could decrease the bond strength, whereas only increasing the nozzle standoff distance exhibited limited effects on that. The weak bond strength could be attributed to the high local porosity at the interface of the specimen. Additionally, numerical simulations of the uniaxial tensile test were conducted using a 2D lattice fracture model, which can predict the bond strength of printed specimens for different void content in the interface layer.

Design and implementation of a crossflow turbine for Pico hydropower electricity generation

This study covered the design, implementation and performance evaluation of a crossflow turbine at various nozzle positions. The chosen blade material was analyzed using ANSYS for stress and deformation degree under the impact of hydraulic jets to ascertain its suitability while in operation. The shaft was analyzed under static and dynamic conditions using ANSYS in order to ensure a non-plastic deformation of the shaft at both conditions. The outcome of this analysis was employed in the harmonic response analysis of the runner shaft. Convergent tests were done for both the blade and runner shaft analysis. An experiment was designed for the evaluation of the crossflow turbine performance using optimal (custom) design tool of response surface methodology and 69 simulations/runs were obtained. The factors considered in the experimental design are: nozzle distance from the shaft, nozzle height and attack angle. The crossflow turbine was constructed using computed design values for all the machine's parts. The runner blades were positioned specifically at 28° outer blade angle and 90° inner blade angle. The turbine was tested under a water head and flow rate of 6.4m and 0.0042m3/s respectively. The shaft power and efficiency were evaluated using their respective formula. The responses were optimized in order to get the optimum position of the nozzle that would give the best performance of the responses using the two factor interaction (2F1) mathematical models in coded factors, developed for each of the response. The results obtained, proved that low carbon steel material was suitable for the turbine blading and the shaft is safe at both static and dynamic conditions since the induced stresses and deformations never exceeded the permissible range. Also, each of these considered nozzle positions had a significant effect on the responses with the nozzle height and attack angle having a combined effect on the performance of the turbine. The best turbine performance was obtained at lower angle of attack, nozzle distance very close to the runner shaft and at a nozzle height that will actualize greater energy impartation to the upper and lower blade profiles. The developed mathematical models for each response has higher correlation value, suggesting that the models are suitable for predicting the responses at the considered factor levels. An optimal nozzle distance, height and attack angle of 102mm, 413mm and 5° respectively, were obtained. At this nozzle position, the alternator gave an output of 35watts and 6V. When two voltage transformers were employed, it gave 200Volts AC. The turbine can be commercialized on large scale for greater output power using the determined optimal nozzle positions.

Performance optimization of rectangular flat pleated filter with slit nozzle for dust cleaning

This work attempted to explore the causes of incomplete cleaning on the top of rectangular flat pleated filter cartridges, and designed newly developed slit nozzle to remove the caked-on dust of the dead zone. In this study, 7 slit holes (length 39 mm × width 1 mm) were designed to compare the peak pressures on the surface of the filter with circular nozzle (7 holes per pipe and the diameter of each hole is 7 mm) under the pulse pressures of 0.3 and 0.4 MPa, the jet distances of 20–100 mm, the filtration velocity of 0.8 m/min and the dust mass concentration of 20 g/m3. The experimental results showed that the optimum distance of circular nozzle was 20 mm, while that of slit nozzle was 20–40 mm, which can enlarge the application range of jet distance. Under the optimum distance, the pressure difference between the upper measuring point P1 and P4 was above 1000 Pa with circular nozzle, while that between the point P1 and P4 was below 400 Pa at the same conditions with slit nozzle. The experimental results also showed when the jet distance was less than 40 mm, the residual dust and systematic resistance under slit nozzle were lower than those of circular nozzle. The newly developed slit nozzle overcame the cleaning difficulty on the top of the filter cartridge and was beneficial for the industrial application.

Analysis of electrostatic solid lubricant spray process parameters during turning Ti-6Al-4V alloy

Titanium alloys are considered as hard-to-cut material due to its relatively high resistance to corrosion, low thermal conductivity and high chemical reactivity. Effective penetration of sufficient amount of lubricant in the metalworking process is of utmost importance to (a) reduce frictional resistance at the high-temperature tool–workpiece interface and (b) avert the formation of built-up edge in machining process. Traditionally, the lubricant forms a thin fluid film to reduce the friction. In order to reduce or eliminate coolant usage and to apply lubri-coolant efficiently at tool–chip–workpiece interface, a novel near-dry machining technique called electrostatic charged solid lubricant spray system has been developed. In electrostatic charged solid lubricant spray technique, the aerosolized micro-droplet particles were sprayed from the nozzle tip which uses a phenomenon called contact-charge electrification principle. The quick penetration and wettability of charged atomized droplet particles are impinged with high velocity at the tool–chip interface. The focus of the present experimental research is to analyse the optimum lubrication process parameters of the experimental set-up in terms of effectively applying cutting fluid in the machining zone. The study shows that the desired atomization and machining performance of the electrostatic charged solid lubricant spray technique can be obtained by governing different spray parameters (lubricant flow rate, air pressure, spray nozzle position, nozzle distance, electrostatic voltage). The results revealed that when the charged lubricants are applied with high velocity and large number of droplets, it will have significant influence on surface roughness and cutting force. The fabricated electrostatic charged solid lubricant spray technique provides us with an efficient and economic machining solution by applying solid lubricants effectively at tool–material interface during turning of Ti-6Al-4V alloy material. The present approach and the obtained results will help in better understanding of the machinability of hard-to-cut materials in manufacturing industries.

Performance Evaluation of Portable Hot Water Jet for Frozen Meat Industry Application

High temperature-induced water jet has important cleaning factors for effective cleaning at food industries because it can provide mechanical, heat, and chemical effects during cleaning. It can also reduce cleaning time, labor load, and utility consumptions, hence reducing the operating costs and enhance sustainability. However, it has not been used widely in small and medium food industries due to a lack of cleaning awareness and small budget allocation for cleaning and disinfection. In this article, we evaluated the performance of a portable water jet in the laboratory before it was introduced to the frozen meat industry. Removal of invisible fat-based fouling deposits which remained on the surfaces of the meat processing equipment is quite a challenge. In this work, stainless steel surfaces were fouled with the fat-based fouling deposit. The fouled stainless-steel surfaces were used for the cleanability tests. The tests were conducted at different parameters which were cleaning parameters (temperature (35 °C and 65 °C) and cleaning detergent presence), cleaning operations (nozzle distances (5 cm and 30 cm)) and surface geometries (vertical and horizontal) which representing the different equipment’s geometry. Physical cleanliness (visual and touch) and protein residue swab test was used as the cleaning indicators. The target cleanliness was achieved at a high cleaning temperature of 65°C and with the presence of cleaning detergent. Results from these tests will be used as a guide to design an optimal cleaning program for SMEs frozen meat patty factory.

PENGARUH VARIASI PARAMETER KECEPATAN TORCH, TEKANAN OKSIGEN DAN JARAK NOZZLE TERHADAP MATERIAL REMOVAL RATE PADA PROSES OTOMASI GAS CUTTING

The number of industries that make building, bridge and machine construction are inseparable from the metal cutting process, to produce optimal output, the process is done automatically. Gas Cutting is a metal cutting technique that uses a combination of oxygen gas and fuel. The purpose of this study was to determine the most optimal combination of low carbon cutting fabrication processes with variations in the Torch Speed ​​parameter (mm / min), Oxygen Pressure (Kg / cm2), Nozzle Distance (mm) to produce the greatest MRR using the taguchi method. From the research, the most optimal combination of parameters on MRR is level 3 torch speed of 475 mm / minute, oxygen pressure at level 3 of 7.5 kg / cm2 and nozzle distance at level 2 of 6 mm. with the contribution of torch speed contribution of 87.39%, oxygen pressure of 10.35%, the effect of the nozzle distance parameter of 1.17%.

Experimental study of oil mist characteristics generated from minimum quantity lubrication and flood cooling

Abstract The use of metalworking fluids during machining can generate oil mist and endanger the health of workers. In order to study the characteristics and emission laws of oil mist generated by machining, this study constructed a test bench to simulate the turning process. Parameters affecting the oil mist generated in the minimum quantity lubrication (MQL) mode and flood cooling mode were studied by means of single-factor experiments, and the formation mechanisms of oil mist were analyzed. The results show that the oil mist generated by the MQL system has two main sources, the initial escape of oil mist into the air and the evaporation/condensation of oil mist. The centrifugation has almost no effect on oil mist formation in the MQL mode. The mass concentration of oil mist generated by the MQL system is proportional to the cutting oil flow rate. When the work-piece is at room temperature, increasing the air supply pressure and nozzle distance, increases the oil mist mass concentration. For the flood cooling mode, the concentration of centrifugal aerosol is linearly and positively correlated with the relative centrifugal force generated by the work-piece, and the coefficient of determination (R2) is above 0.97. The oil mist mass concentrations in MQL mode is 8.33 mg/m3~ 305.88 mg/m3. The MMD and SMD are 0.74 µm to 4.42 µm and 0.31 µm to 2.14 µm, respectively. The oil mist mass concentrations in flood cooling mode is 0.2 mg/m3~ 22.42 mg/m3. The MMD and SMD are 1.81 µm to 6.58 µm and 0.45 µm to 5.13 µm, respectively.

Experimental Analysis on Influencing Factors of NOx emission in Gas-Fired Heating and Hot Water Combi-Boilers

To study the influencing factors of NOx emission in gas-fired heating and hot water combi-boilers, a boiler with the maximum heat input of 26.0 kW was selected, and influencing factors including flue restrictor diameter, fan power, nozzle aperture, nozzle ejection distance and air relative humidity on NOx formation were determined. The NOx test rig has been built and the concentration of NOx at the rated heat input and the NOx weight value (NOx)pond with different heat input in the dry flue gas have been tested respectively according to the test methods in Chinese national standard GB 25034-2010. The results show that with the increase of the diameter of flue restrictor at exhaust outlet, the NOx concentration at the rated heat input and the NOx weight value (NOx)pond with different heat input in the dry flue gas decreased by 26.9% and 5.9%; with the increase of the diameter of flue restrictor at air intake inlet, the NOx and (NOx)pond decreased by 36.5% and 16.0%; with the increase of fan power, the NOx and (NOx)pond can be decreased by 48.4% and 16.1%; with the increase of ejection distance of nozzle, the NOx and (NOx)pond decreased by 7.7% and 6.8%; with the increase of aperture of nozzle, the NOx and (NOx)pond increased by 5.2% and 2.3%; with the increase of air relative humidity, the NOx decreased by 16.4% and the (NOx)pond basically remains unchanged. The analysis of the influence factors of NOx emission can be provided as reference for the optimization design of combi-boilers with low NOx emission.

Analysis of Influencing Factors on NOx emission in Gas-Fired Heating and Hot Water Combi-Boilers Based on Orthogonal Method

In order to determine the sensitivity of influencing factors on NOx emission in gas-fired heating and hot water combi-boilers, the orthogonal method was adopted in this paper. Five predominant factors affecting the formation of NOx and four levels were selected to be analyzed, including the diameter of flue restrictor, power of fan, ejection distance of nozzle, aperture of nozzle and relative humidity of air. The test plan was designed by employing L16(45) orthogonal array, and 16 groups of experiments were conducted. The test results were analyzed with range analysis and variance analysis. The results indicated that the power of fan has the greatest influence on the formation of NOx of the gas-fired combi-boilers, followed by the diameter of flue restrictor and the relative humidity of air, while the ejection distance of nozzle and aperture of nozzle have little effect on the formation of NOx. In addition, with the selected optimal combination of five factors, a minimum NOx volume fraction is obtained, which confirms the superiority of the orthogonal test. The research finding has a certain guiding significance for the reduction of NOx formation of gas-fired heating and hot water combi-boiler.

Atmospheric flame vapor deposition of WO3 thin films for hydrogen detection with enhanced sensing characteristics

Nowadays, with the increasing demand for hydrogen, sensors that can detect low concentrations of this gas are essential for its safe use. In this paper, Pd/WO3 film hydrogen sensors are developed using a solid-feed flame vapor deposition (SF-FVD), as an atmospheric, economical, and fast film fabrication method. The crystal structure and morphology of the samples were characterized by different means. The performance of the obtained sensors was investigated for different hydrogen concentrations (1–2500 ppm) and at different operating temperatures (100–250 °C). We attempted to determine the optimum deposition conditions, including feed and substrate to flame nozzle distances. In most of the sensing conditions, the response and recovery times were measured in the order of 20 to 30 s. The layer with a more open morphology showed sensitivity at ppb hydrogen level, good stability, and selectivity. The response behavior of the samples was explained according to the power-law in the metal oxide semiconductor (MOS) gas sensors.

Dual-processing by abrasive waterjet machining—A method for machining and surface modification of nickel-based superalloy

Abstract Abrasive waterjet (AWJ) is widely used for machining of advanced (e.g. nickel-based) superalloys as it offers high material removal rates and low cutting temperatures. However, the inadequate surface integrity, e.g. large number of scratches and embedded particles in the machined surface, which would induce severe deteriorations of the materials functional performance, has been one of the greatest issues of the AWJ machining technique. To solve this problem, this research proposed a dual-process abrasive waterjet machining method, whereby two different functions of abrasive waterjet were employed: materials removal (first process) and surface modification (secondary process), hence, to improve the workpiece surface integrity. Two types of entrained particles, i.e. with sharp cutting edges (e.g. garnet) and smooth surfaces (e.g. stainless steel ball), that depending on their kinetic energy density can either cut or modify the workpiece surface respectively, are employed for these the two constitutive processes of the proposed dual-waterjet machining method. A critical standoff distance and inclination angle of the waterjet nozzle has been defined for the surface modification process thus, to eliminate the embedded particles and scratches left by the first cutting process while also introducing a surface strengthening effect. To support this approach, a mathematical model has been proposed for determining the surface modification parameters (e.g. jet feed speed and abrasive flow rate). In-depth analysis of the microstructural and metallurgical alternations of the machined workpiece surface and superficial layer have also been conducted to reveal the mechanisms responsible for the surface damage elimination and surface strengthening. Moreover, a four point bending fatigue test has been conducted to validate the mechanical performance, whereby a significant improvement of the fatigue life on the machined workpiece was achieved when compared with the case that single AWJ cutting method (91 %) and conventional machining (34 %) are employed. This proves that the proposed dual-processing AWJ machining method is of high efficiency to improve the functional performance of components on a single machine tool platform.

The Surface Morphology of a Ti–6Al–4V Fiber-Lasered Nitride Layer

A fiber laser was used to nitride Ti–6Al–4V titanium alloy the effect of the process parameters on the surface morphology was studied. The surface chemical composition of the nitride layer and the phase of black powder on the surface were analyzed, the two-dimensional and three-dimensional surface topography of the nitride layer surface were measured, and the cross-section microstructure of the nitride layer was photographed. The effects of laser power, laser scanning speed, nozzle distance, and nitrogen flow rate on the surface morphology were studied. The experiments show that the laser power mainly affects the surface oxidation, the laser scanning speed mainly affects the surface roughness, and the nozzle distance has a great influence on the surface morphology. The gas flow rate, however, had a slight effect on the surface morphology. A large heat input and a high nitrogen flow rate caused an increase in TiN and TiO2 black powders. Surface oxidation did not affect the formation of a continuous TiN layer nor surface roughness. Finally, the critical energy density leading to increased surface roughness was calculated.

Predictive models for characterizing the atomization process in pyrolysis of methyl ricinoleate

Abstract Pyrolysis of methyl ricinoleate (MR) can produce undecylenic acid methyl ester and heptanal which are important chemicals. Atomization feeding favors the heat exchange in the pyrolysis process and hence increases the product yield. Herein, predictive models to characterize the atomization process were developed. The effect of spray distance on Sauter mean diameter (SMD) of atomized MR droplets was examined, with the optimal spray distance to be 40–50 mm. Temperature mainly affected the physical properties of feedstock, with smaller droplet size obtained at increasing temperature. In addition, pressure had significant influence on SMD and higher pressure resulted in smaller atomized droplets. Then, a model for SMD prediction, combining temperature, pressure, spray distance, and structural parameters of nozzle, was developed through dimensionless analysis. The results showed that SMD was a power function of Reynolds number (Re), Ohnesorge number (Oh), and the ratio of spray distance to diameter of swirl chamber in the nozzle (H/dsc), with the exponents of − 1.6618, − 1.3205 and 0.1038, respectively. The experimental measured SMD was in good agreement with the calculated values, with the error within ± 15%. Moreover, the droplet size distribution was studied by establishing the relationship between the standard deviation of droplet size and SMD. This study could provide reference to the regulation and optimization of the atomization process in MR pyrolysis.