Outlet Velocity Research Articles

Study on seepage characteristics of cross fractures in adjacent and convective flow modes

The distribution of fractures in the underground rock mass is complex, so it is of great significance to study the parameter characteristics of fracture seepage for geothermal exploitation, land subsidence, and other fields. Based on the Weierstrass-Mandelbrot function, several X-shaped fracture models with different roughness are established, and the fracture seepage law under different roughness and inlet pressure is studied. At the same time, the center (cross-region) of the X-shaped fracture is selected as the research object, and the seepage difference characteristics of the cross-region under the two inlet modes of adjacent flow and convective flow are compared and analyzed. The results show that the outlet velocity of fracture fluid is inversely proportional to the fractal dimension and is directly proportional to the inlet pressure.

Airflow distribution law of multi-branch pipe of pneumatic rice direct seeder based on dimensional analysis

In order to investigate the flow characteristics and distribution law of airflow in multi-branch pipe of pneumatic rice precision direct seeder and obtain the mathematical model between airflow parameters and pipe geometry structure. In this study, the airflow flow law of the multi-branch pipeline of the pneumatic system was studied, the mechanism of airflow flow in the multi-branch pipe was analyzed, and it was clarified that the main factors affecting the airflow flow in the pipe, namely, air density, air dynamic viscosity, the total flow rate of the inlet branch pipe, the length of the closed end of the header, the inner diameter of the outlet branch pipe, and the outlet branch pipe spacing. Numerical simulations were carried out using Fluent simulation software to elucidate the cause of multi-branch pipes of uneven distribution of airflow in multi-branch pipes, the empirical equation among these factors and the flow velocity of the outlet branch pipe are established by dimensional analysis method. The bench test results show that the established empirical equations are applicable in the following ranges: 0.018 m3/s≤Q≤0.054 m3/s, 0.045 m≤d≤0.05 m, 0.075 m≤L≤0.125 m, 0.7 m≤Y1≤0.875 m (0.5 m≤Y2≤0.75 m, 0.36 m≤Y3≤0.45 m), the prediction accuracy can be controlled within 10% of the empirical formula, which can provide a reference for the prediction and optimization design of outlet velocity of the multi-branch pipe. Keywords: pneumatic system, multi-branch pipe, axial momentum conservation, Fluent, dimensional analysis DOI: 10.25165/j.ijabe.20231601.7663 Citation: Qin W, Wang Z M, Zhang M H, He S Y, Wang X G, Jiang Y C, et al. Airflow distribution law of multi-branch pipe of pneumatic rice direct seeder based on dimensional analysis. Int J Agric & Biol Eng, 2023; 16(1): 111–127.

Optimization of the cooling strategy during cryogenic milling of Ti-6Al-4 V when applying a sub-zero metalworking fluid

Due to an excellent ratio of high strength to low density, as well as a strong corrosion resistance, the titanium alloy Ti-6Al-4 V is widely used in industrial applications. However, Ti-6Al-4 V is also a difficult-to-cut material because of its low thermal conductivity and high chemical reactivity, especially at elevated temperatures. As a result, machining Ti-6Al-4 V is characterized by high thermal loads and a rapidly progressing thermo-chemical induced tool wear. An adequate cooling strategy is essential to reduce the thermal load and therefore tool wear. Sub-zero metalworking fluids (MWF) which are applied at liquid state but at supply temperatures below the ambient temperature, offer great potential to significantly reduce the thermal load when machining Ti-6Al-4 V. Within the presented research, systematically varied sub-zero cooling strategies are applied when milling Ti-6Al-4 V. The influences of the supply temperature, as well as the volume flow and the outlet velocity are investigated aiming at a reduction of the thermal loads that occur during milling. The milling experiments were recorded using high-speed cameras in order to characterize the impact of the cooling strategies and resolve the behavior of the MWF. Additionally, the novel sub-zero cooling approach is compared to a cryogenic CO2 cooling strategy. The results show that the optimized sub-zero cooling strategy led to a sufficient reduction of the thermal loads and does outperform the cryogenic cooling even at elevated CO2 mass flows.

Investigation on the Influence of Flow Passage Structure on the Performance of Bionic Pumps

The flapping hydrofoil bionic pump drives the hydrofoil to make simple harmonic motion and completes one-way water pumping in the flow passage. As a new pump device that can realize ultra-low head water delivery, the flapping hydrofoil device can effectively enrich the drainage methods of plain rivers and improve water delivery efficiency, and the passage structure is the key factor of ultra-low head devices. In this paper, the two-dimensional flow passage models are established, and the flapping of the airfoil is realized by using the dynamic grid technology. Based on the continuity equation, k-ε turbulence model, and Reynolds time-averaged equation, the flapping hydrofoil device is simulated by transient calculation. The hydraulic performance characteristics of various passages with different widths, such as square passages, micro-arc passages, and convergent–divergent passages, are calculated and simulated. The results show that, under the fixed motion parameters, the narrower the passage width, the higher the outlet velocity, lift, and efficiency of the device, the lower the flow rate. The contraction–expansion pipe can effectively improve the efficiency and flow rate of the device, and, before the wake is stable, the longer the contraction section the better the lifting effect. However, the micro-arc pipeline will affect the formation of a double-row anti-Karman vortex street, resulting in greater energy loss and in its hydraulic performance being inferior to that of the square passage.

Performance prediction of centrifugal compressor based on a new volute loss model and corrected theoretical work

AbstractPerformance prediction plays an important role in the predesign stage of centrifugal compressors. A set of loss models is usually selected and grouped to fulfill the above prediction. To improve the defects of traditional prediction, we modified the outlet velocity and slip coefficient of the impeller by means of the energy average method to obtain theoretical work. A new volute loss model is proposed to replace the traditional semiempirical loss model by adopting a suitable loss model for each flow passage component. A proper performance prediction method is established for the centrifugal compressor studied in this paper. The overall performance of a single‐stage centrifugal compressor is predicted and compared with experimental and numerical simulation results. It is found that the prediction method proposed can better predict the overall performance of the centrifugal compressor. And the volute loss is the third largest loss after impeller loss.

Experimental and Theoretical Investigations of a Plate-Fin Water Intercooler Equipped in a Boosted Diesel Engine

Abstract Intercoolers utilized in turbocharged engines are critically essential to efficiently improve the engine volumetric efficiency and therefore the engine specific power. Although boosting the internal combustion engines has been extensively investigated, further studies are required to provide relevant approaches to optimize the heat transfer coefficient. This paper experimentally and theoretically investigates the influence of inlet coolant velocity on heat transfer characteristics of an air-to-water intercooler equipped in a turbocharged diesel engine. This aims to optimize the heat transfer rate from water to air under typical engine operating conditions. The experiment has been conducted using a fully equipped engine testbed. The engine is turbocharged with a plate-fin intercooler. The intercooler is a perpendicular air–water heat transfer system that could be suitable for boosted marine engines or power generators. A simulation model was also developed using the finite volume model in the ansysfluent package. The distributions of inlet and outlet temperature, pressure, and velocity of air and coolant under various inlet water velocity and engine operating conditions are examined. The optimal heat transfer rate from air to water was achieved for this intercooler. The outlet air temperature after the intercooler decreases by about 10 °C, engine thermal efficiency increases by 0.7% approximately, engine power enhances by 2.5%, and the specific fuel consumption decreases by 0.82%. The CFD simulation and experiment model developed in this study for the plate-fin water intercooler could be a useful approach to optimize other intercooler systems. In this study, with a 270 × 270 × 10 mm plate-fin perpendicular air–water intercooler, an optimal cooling water velocity of 1.0 m/s, corresponding with a flowrate of 1780 liter/hr, is achieved.

CFD Analysis of a Small-Scale Solar Chimney Exposed to Ambient Crosswind

Solar chimneys are devices that use solar energy to generate a hot airflow that can be used for power production, the drying of agricultural products, and/or water desalination. The performance of a small-scale solar chimney is studied numerically. The computational domain includes the solar chimney, the ground, and the atmosphere. The turbulent airflow is simulated using the commercial CFD code Ansys Fluent. The only boundary conditions required for the simulation are the wind speed, the ambient temperature, and the absorbed energy from the ground, determined by an energy balance in the system. The system was simulated for one day in the summer in the city of Belo Horizonte, Brazil. The ambient crosswind plays an important role in the velocity and temperature. The velocity inside the solar chimney increased with the wind speed, increasing the heat transfer and decreasing the airflow temperature. When the wind speed increased from 0 to 10 m/s, the outlet velocity increased from 1 to 4 m/s, and the outlet temperature decreased from 313 to 304 K.

Investigations on the Interfering Factor of Single Synthetic Jet Actuator on Improving the Efficiency of Wing Control Surface

After the deflection of the wing control surface, flow separation is easily generated at the trailing edge of the wing, which will reduce the lift coefficient and the control surface efficiency. The rudder of the wing is aileron. If the lift generated by the wing is used to improve the efficiency of the control surface, the flow separation caused by the deflection of the control surface must be restrained. Using synthetic jet to change the flow state of boundary layer is the main method to solve the problem of flow separation. Synthetic jet actuator (SJA) has the advantages of no energy loss and simple structure. In this paper, a method of using synthetic jet actuator to suppress the flow separation at the rear of the wing when the aileron deflects is proposed, and the lift coefficient is obtained. The increase of aileron efficiency is calculated by the change of lift coefficient. The EPPLER555 wing with aileron deflection angle of 3°~9° is simulated, and the changes of lift coefficient and aileron efficiency under corresponding working conditions are obtained. The results show that the average lift coefficient of the wing is 0.5 when the deflection angle of the aileron is 3°~9° without SJA. After SJA employed, the lift coefficient will be greatly improved, and the control surface efficiency of EPPLER555 wing will be effectively improved, the lift coefficient will increase by about 20% to 0.6-0.7. For example, when the deflection angle of aileron is 4°, using a SJA with a maximum outlet velocity of 200m/s and an excitation frequency of 400/2π, the effective lift coefficient generated by the wing is 0.5931. Under the effect of SJA, the control surface efficiency of EPPLER555 wing will be effectively improved. The lift coefficient is reflected by the ratio of the change of lift coefficient after SJA employed to the lift coefficient without synthetic jet actuator.

Negative corona discharge and flow characteristics of a two-stage needle-to-ring configuration ionic wind pump for temperature and relative humidity

Ionic wind pumps have the advantages of a compact structure, no moving parts, and low power consumption. The effects of temperature and humidity on the current–voltage and flow characteristics of ionic wind pumps are still unclear. This study experimentally investigates the effects of temperature and humidity on the breakdown voltage, discharge current, and velocity of a two-stage needle-to-ring type ionic wind pump with a negative corona discharge. It is found that the coupling effects of temperature, humidity, and water vapor condensation determine the current–voltage and flow characteristics of ionic wind pumps. The temperature and vapor condensation effects can enhance the discharge current and outlet velocity and weaken the breakdown voltage. However, the humidity effect can weaken the discharge current and outlet velocity, and improve the breakdown voltage. Moreover, there exists a competition between humidity and vapor condensation effects on breakdown voltage, current, and velocity. The increase in temperature intensifies the humidity effect and weakens the condensation effect; thus, the temperature changes the contribution of humidity and condensation effects in the competition. A working spectrum of ionic wind is provided in the temperature and humidity coupling environment, including a vapor condensation-controlled zone, a sensitive humidity zone for breakdown voltage and velocity, and an insensitive humidity zone for breakdown voltage and velocity. The spectrum can provide theoretical guidance for designing ionic wind pumps at different temperatures and humidity.

Approaches to tailor the cooling supply to the grinding process

This study presents original research of the investigation of the coolant supply to the contact area with two different approaches. The cooling and lubrication are key aspects of manufacturing processes such as grinding to achieve a high surface quality at high productivity. The coolant supply to the contact area has a high impact on the performance of the coolant. This paper presents the results from two approaches to tailoring the coolant supply for conventional and high-performance processes. An analytical approach is established to determine the coolant outlet velocity. Afterward, a sensor is developed to measure the coolant velocity at the nozzle. Conclusively, the influence of the coolant velocity on the volume flow through the contact zone is investigated. The results of this study highlight the importance of coolant outlet velocities of at least 60% of the cutting speed. The two approaches outline low impact possibilities to ensure optimal coolant outlet velocities and thus low thermal loads during the grinding process.Article HighlightsAnalytical approach to calculate outlet velocities for varying noozles in high-performance grinding with cutting speeds of up to 100 m/sUtilization of a high-speed camera to determine the outlet nozzle velocities in a conventional deep grinding processValidation of the impact of the coolant outlet velocity on the volume flow through the contact area by means of a coolant collection box

Numerical Simulation of Tail Over-Fire Air Supply of a Grate Biomass Boiler

By taking a 130 t/h water-cooled grate biomass boiler as the research object, the ANSYS software is applied to simulate the effects of the tail burnout air’s incidence angle, wind speed, and pipe diameter on flow field distribution in the furnace, the movement of unburned carbon particles at the tail of the grate under cold operation. The influence rules of the incidence angle, pipe diameter, and wind speed of the tail burnout air on the combustion in the furnace and the movement of the tail particles were obtained. The results show that the setting of burnout air at the tail of the grate can better organize the air flow field at the grate tail, change the particle distribution, prevent small density particles from directly falling into the ash hopper, and prolong the residence time of particles on the grate. Under the study conditions, with an increase in the outlet velocity and the pipe diameter of the tail burnout air, as the movement degree and the burnout degree of grate particles increase, the boiler efficiency increases. With an increase in the incidence angle of the tail burnout air, the flow field in the furnace and the reduction ratio of the tail particles increases at first and then decreases, and the optimal incidence angle is 11–13°.

Influences of main design parameters on the aerodynamic performance of a micro-radial inflow turbine

The micro-radial inflow turbine (MRIT) is not only an important component of a micro-gas turbine but also the core part of a vehicle exhaust gas turbocharger and a small-scale organic Rankine circulatory system. Therefore, designing an MRIT with good performance is of great importance. The values of some main turbine design parameters can significantly influence its aerodynamic performance and structural size. In accordance with the structural characteristics of an MRIT, the relationships between the aerodynamic performance of a turbine and the absolute flow angle at the rotor inlet, the relative flow angle at the rotor outlet, the nozzle and rotor blade velocity coefficients, the ratio of the wheel diameter, velocity ratios, and the degree of reaction were examined. This was done through theoretical analysis combined with experience in the design of a conventional radial inflow turbine. On this basis, the influencing laws and degrees of the seven main design parameters on the aerodynamic performance of an MRIT during aerodynamic design were analyzed. The selection principles of these main design parameters were also summarized. The reasonableness of the above-mentioned selection principles was verified through an aerodynamic design case study of an MRIT combined with a 3D numerical simulation. It was found that the 3D numerical simulation results agreed well with the 1D aerodynamic design. The summarized selection principles of the main design parameters can provide a reference for the successful aerodynamic design of an MRIT.

Use of basin outlet velocity to determine the basin concentration time and storage coefficient

Abstract Most empirical formulae for the basin concentration time (Tc) and storage coefficient (K) focus on estimating the representative values under the ordinary condition, with their return period being a maximum of 100–200 years. Under more extreme conditions, those parameters should be modified to consider faster velocity conditions. The main objective of this study is to examine the possibility of determining these parameters corresponding to the given peak velocity (vp) at the basin outlet. Two issues are involved in this problem; one is whether Tc can be fully expressed by vp, while the other is whether K is still linearly proportional to Tc under extreme conditions. In this study, these two issues are resolved by the theoretical review of these parameters, as well as an analysis of the rainfall–runoff events collected at the Chungju Dam basin, Korea. It is observed that as vp increases, Tc and K decrease. Their relationship is close to inverse but in linear proportion. That is, strong linear relationships are found among Tc, K, and vp. As a result, the ratio of K to Tc is found to be almost identical, regardless of vp. This ratio at a basin can be assumed as a basin characteristic that is unchanged, regardless of the size of rainfall events.

Thermal Performance Improvement of Modified Hemispherical Cavity Receiver with Air Curtain

Heat losses from solar cavity receivers degrade the efficiency of solar parabolic dish collector system. Specifically, increased convection losses emulate a significant contribution in decreasing the performance of the modified solar cavity receiver and hence, reducing these convection losses has become a matter of great concern. The Air curtain plays a crucial role in minimizing the convection losses. This work proposes an air curtain-based modified cavity receiver wherein a plane nozzle is placed on the face of receiver to produce air curtain effect. Air curtain will prevent hot air from escaping the modified cavity receiver and increase the stagnation zone inside it to reduce natural convection on the surfaces. Numerical analyses are performed considering different air velocities and receiver orientations to evaluate the effect of air curtains on the convection losses. The impact of plane air nozzle parameters like outlet temperature, inclination, and outlet velocity of the nozzle on convection losses are shown and these parameters’ optimal value is evaluated. Our results state that the air curtain attached to the modified solar cavity receiver significantly improves performance by reducing the convection losses.

CFD analysis of base drag reduction using indent modification in suddenly expanded nozzle

The total drag is the combination of skin friction, wave and base region drags. With all moving projectiles, rockets, missiles, and launch vehicles, the base pressure at the base or back face is a common concern. Base drag increase in unexpectedly bigger flows due to a sudden expansion of duct size at exhaust. At the duct’s outflow, the base pressure is vacuum or sub-atmospheric. To lower the base drag, the vacuum must be increased to near atmospheric pressure to reduce total drag. Base drag is undesirable since it accounts for a large portion of the total drag. The reduction in base drag benefits the space and defense programmers greatly. This is highly responsible to major losses of energy as a result of drag. Out of the different types of drag, base drag, commonly known as wake drag is responsible for increased drag in case of high velocity flow through the nozzles. Henceforth it is imperative to have drag reduction techniques. There are active or passive methods used to reduce base drag. The proper recovery of base pressure can be done by optimum indent geometry and position optimization. In this numerical analysis, different geometric shape and position indents are used on the exhaust duct so at to reduce base drag. It was found from the analysis that the outlet velocity radically alters from the inlet to outlet. Furthermore, the magnitude of velocity was high for the nozzle with a circular indent when compared with other indent geometries in the analysis.

A Study of Swirling Jet Drilling and Its Specific Energy for Hydrate-Bearing Sediments

SummaryNatural gas hydrate (NGH) is a form of clean energy. The marine NGH solid fluidization exploitation method and the integrated radial jet drilling and completion method are considered as two ways to improve gas production, and water jet is the key technology of the two mining methods. This paper first compared the flow field distribution of conical jet and swirling jet at different outlet velocities through numerical simulation. The volume change of conical jet and swirling jet erosion hydrate-bearing sediment (HBS) was analyzed when the jet outlet velocity and standoff distance were changed. Then, based on the experimental apparatus for NGH generation and jet erosion, we carried out the swirling jet erosion HBS experiments. The depth and diameter of the erosion pits were about 10% larger than the numerical simulation. Finally, we evaluated the jet erosion performance with specific energy calculations. The results show that the reaming ability of the swirling jet is 2.4 times than that of the conical jet at the jet velocity of 100 m/s and the standoff distance of 5 mm. When the jet velocity ranges from 30 to 100 m/s, the erosion efficiency of the swirling jet is higher than that of the conical jet. The critical standoff distance is calculated as 12.5 mm (12.5 times nozzle throat) in current study, larger than which the advantages of swirling jet erosion HBS become less obvious. The excellent performance of swirling jet erosion HBS under certain conditions is described by specific energy calculation. This study can help for better understanding the performance of water jet drilling and provides an idea for improving the production efficiency of NGH.

A novel staggered split absorber design for enhanced solar chimney performance

Solar chimney enables passive ventilation in green buildings, without drawing electricity from the grid. The factors influencing the performance of this sustainable passive ventilation device have been widely studied. However, more work needs to be done to increase the induced flow rate, which is crucial to enhance the attractiveness of this ventilation method. This study highlights the importance of high uniformity of outlet velocity distribution which can be achieved through distributed heating of the air in a solar chimney, leading to the staggered split absorber design proposed in this study. The flow rate induced by this novel solar chimney design is predicted numerically using an experimentally validated model and compared against the conventional solar chimney design. This novel absorber configuration results in higher flow uniformity at the chimney outlet and increases the ventilation rate by 57.0%, from 0.194 kg/s to 0.304 kg/s, for a solar chimney of 2.8 m in height, 1 m in width and 0.84 m in depth under 600 W/m2 solar irradiance.

Simulation study on the injection performance of the gas-solid injectors for large particles

Gas-solid injectors are a power source of particles in pneumatic conveying systems. The momentum and energy exchange between particles and the flow field occurs for the first time in a gas-solid injector. The structural parameters of gas-solid injectors have a direct impact on the state of motion of particles. In the previous experimental study [1], we obtained the optimal structural parameters of a gas-solid injector under experimental conditions. However, there were many problems, such as the high cost of experimental equipment, high consumption of human and material resources, and long experimental time. In particular, the amount of reference data obtained from the experiment was limited, and the experimental results had certain manufacturing, human and accidental errors. Therefore, in this paper, the CFD-DEM coupling method is used to simulate the structural parameters affecting the performance of gas-solid injectors. The ejection ratio, energy consumption ratio, residue particle mass, particle outlet velocity, particle conveying ratio, percentage of total particle energy and total energy consumption ratio are adopted as the corresponding indicators to explore the relevant evaluation parameters that are difficult to obtain by experiment. The optimized structural parameters of the gas-solid injector under the corresponding indicators are obtained, which provides a design reference for the gas-solid injector and pneumatic conveying system under different working conditions. • Evaluation indicators obtained by CFD-DEM are difficult to obtain experimentally. • Optimal structure parameters are obtained under different evaluation indicators. • Nozzle length has the most significant effect on ejection performance. • Residual particle mass should be taken as primary indicator to avoid blockage. • Energy consumption should be taken as important indicator to improve efficiency.

Numerical modeling of the effect of nozzle diameter and heat flux on the polymer flow in fused filament fabrication

A numerical model that fully account for the velocity of the traveling filament (push velocity) in the liquefier is presented in the current work to predict the pressure, temperature, outlet melt viscosity, strain rate, and velocity in the hot-end of a FFF system for printing tough-poly(lactic acid) (TPLA). The numerical model was thoroughly validated by comparing the model predictions with experimentally measured feeding force data. The predicted numerical results closely approximated the experimentally measured feeding force. Then the model was also validated with extrudate temperature, measured with a thermal imaging camera, and the results obtained are in good agreement. Outlet capillary diameter, feeding rate, and heat flux (quantified in terms of Nusselt number) were varied to determine the response of pressure field, temperature, velocity, viscosity, and strain rate in the liquefier. The results show that an increase in the nozzle outlet diameter decreases the extrusion pressure in the hot-end. The maximum pressure predicted for TPLA is 3.34, 2.91, and 2.04 MPa for the 0.4, 0.6, and 0.8 mm outlet diameters nozzles, respectively. Also, an increase in the nozzle outlet diameter decreases the central velocity at the outlet and decreases the shear rate with an increase in the viscosity of TPLA at the exit during material extrusion. The area-weighted averaged outlet temperature for TPLA decreases as the feeding rate increases for all three nozzle diameters. Elucidated from the simulation results, significant variation of the normalized velocity at the center of the nozzle outlet suggests that different printing speeds for TPLA material extrusion should be set for different nozzle diameters. Otherwise, the accuracy and precision of the gantry motion during layer deposition on the print will be compromised. The simulation results indicate that based on the 90% core melting temperature requirement, at a liquefier set temperature of 503 K, the TPLA should be printed below 80mm/min for all outlet diameters considered. A Nusselt number of 49.61 was observed to be the upper limit where an increase in the heat flux in the liquefier has no significant effect on the area-weighted averaged outlet temperature of TPLA.

Numerical investigation on flow and atomization characteristics of hydrated magnesium nitrate gas-liquid two-fluid nozzle

The aim of this study is to reveal the atomization process of Mg(NO3)2·2H2O generated in the nitric acid leaching process of laterite nickel ore through a nozzle into a pilot pyrolysis furnace using CFD method. Based on the Euler-Lagrange method, a mathematical model of the hydrated magnesium nitrate gas-liquid two-fluid atomization nozzle was established, which can describe the gas-liquid flow characteristics. A visualization experimental platform was built for whose reliability has been verified by using graphical analysis technique. The influence law of gas channel inclination angle (hereinafter referred to as inclination angle), channel number and gas inlet pressure on the velocity inside the nozzle, liquid volume fraction and velocity and particle diameter of the atomization field were further explored. The results show that the number of gas channels is the main influencing factor for the average velocity at nozzle outlet and Sauter Mean Diameter (SMD) of atomized particles, while the gas inlet pressure mainly affects the volume fraction of liquid. When the inclination angle increases, the average velocity of nozzle outlet increases, and the Average Mean Diameter (AMD) and SMD of the atomized particles decrease. At the same time, the average volume fraction of hydrated magnesium nitrate first increased and then decreased, with the maximum value to 27.91% when the angle is 30°. Therefore, the high nozzle outlet velocity can play an important role in promoting droplet fragmentation and the volume fraction of hydrated magnesium nitrate for the later pyrolysis, only when the inclination angle is set properly.