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Abstract

In this article, the electrostatic atomization experimental setup was designed and fabricated, and high-speed camera was used to observe and analyze the atomization modes of graphite water-based and oil-based nanofluid using cutting tool as electrode under different electrode voltages and distances, flow rates, and nozzle angles. Three-dimensional finite element simulations of the electrostatic field between nozzle and cutting tool were conducted using the software Ansoft Maxwell to investigate the effect of electrode voltage and nozzle angle on the electrostatic atomization mode. The results indicate that spindle mode is a suitable electrostatic atomization mode for cooling and lubricating the cutting edge. The nozzle angle with the largest electrostatic field intensity is presented so as to generate good break-up effect of jet in spindle mode. Furthermore, the operating range of spindle mode in terms of the electrode voltage and flow rate for graphite water-based and graphite oil-based nanofluid under the nozzle angle with the largest electrostatic field intensity is achieved. The outcome of this study is helpful for further development of electrostatic atomization cutting technique.

Keywords

Nanofluid electrostatic atomization cutting atomization mode electrostatic field cutting fluids

Introduction

Cutting fluids are generally used in metal cutting process to improve the tribological characteristics of cutting zone and also to remove the heat generated, thus improving the tool life and surface finish. However, the use of conventional cutting fluids creates some problems such as economic cost, environmental pollution, and health hazards. Thus, many efforts have been undertaken to develop some alternatives to cutting fluids which are cryogenic cooling, minimum quantity lubrication (MQL), refrigerated gas cutting, and cryogenic minimum quantity lubrication (CMQL).^1,2

Electrostatic atomization is an atomization method in which the fluid is broken into fine charged droplets by means of electrostatic force. By contrast with other atomization techniques, electrostatic atomization has some advantages as follows: relative ease of droplet generation, great control of droplet transport, ability to avoid coalescence of droplets due to electric charge of the same polarity on the droplets, enhanced adhesion and deposition, and so on.^3,4 All these advantages have led to the application of electrostatic atomization in machining. For effective supply of lubricant at an extremely low flow rate to the machining zone, on the basis of electrostatic atomization technique, Reddy and colleagues^5,6 developed an electrostatic lubrication system, in which cutting tool was used as ground electrode, and conducted a comparative performance analysis of the electrostatic lubrication system with MQL, wet and dry machining during the drilling of AISI 4340 steel and SCM 440 steel. The results obtained from the experiments indicate that there was a considerable improvement in machining performance using the electrostatic lubrication system when compared with MQL, wet and dry machining in terms of thrust force, tool wear, hole diameter, and surface finish.

There are three charging methods used for electrostatic atomization, namely, conduction charging, induction charging, and ionized field charging.⁷ Compared with the other two charging methods, conduction charging provides the better charging effect. Thus, it is especially suitable for the electrostatic atomization of insulating liquids. The electrostatic lubrication system developed by Reddy and colleagues^5,6 is also based on conduction charging. Nanofluids refer to fluids obtained by suspending nanoparticles with average sizes below 100 nm in base fluids.⁸ Recent studies have shown that the suspension of nanoparticles can improve the heat transfer and tribological properties of base fluids.^9,10 Moreover, the addition of nanoparticles can still increase the conductivity of base fluids, consequently improving the electrostatic atomization performance. Thus, it can be reasonably anticipated that more significant benefits may be achieved when using nanofluids in electrostatic atomization cutting. The machining performance depends highly on atomization characteristics during the electrostatic atomization cutting process. Furthermore, the electrostatic atomization behavior is greatly influenced by the electrostatic field. Although the electrostatic atomization characteristics of many fluids such as distilled water, ethanol, and ethylene glycol was studied using plate-shaped and point-like ground electrodes in the past,^11–13 no study is conducted on the electrostatic atomization characteristics of nanofluids using cutting tool as ground electrode until now. Therefore, in this research, the aim is to investigate the electrostatic atomization modes of nanofluids using cutting tool as ground electrode, and the effect of electrostatic field between cutting tool and nozzle on them.

Concept of electrostatic atomization cutting

Figure 1 shows the schematic diagram of electrostatic atomization cutting. The nozzle and cutting tool are connected to the high voltage supply and ground, respectively. When high voltage supply operates, the nozzle generates electric charges whose polarity is the same as that of high voltage supply, and opposite electric charges are induced on the surface of cutting tool. Thus, high-voltage electrostatic field forms between the nozzle and the cutting tool. When the fluid flows through the nozzle, electric charges are induced onto the surface of the fluid to be atomized by conduction charging method. As the fluid surface becomes more charged, the repulsive electrostatic force on the surface of the charged fluid increases. Once the charges the fluid carries exceed the Rayleigh limit, the repulsive electrostatic force overcomes the surface tension and viscous force. Thus, the fluid breaks up into charged droplets. The charged droplets are then accelerated by the electrostatic field, and get attracted to the opposite charges induced on the surface of cutting tool, thus cooling and lubricating the cutting tool.

Figure 1.

Schematic diagram of electrostatic atomization cutting.

Electrostatic atomization experiments

In this research, graphite water-based and oil-based nanofluids were prepared by ultrasonically assisted two-step method. Deionized water and LB2000 vegetable-based lubricant, supplied by Dongguan Qian Jing Environmental Protection Equipment and ITW Rocol North America Co., Ltd, respectively, were chosen as base fluids. Graphite nanoparticles with the diameter of 35 nm, purchased from Beijing DK Nano Technology Co., Ltd, were used throughout these experiments. The properties of nanoparticles and based fluids are given in Tables 1 and 2, respectively.

Table 1.

Properties of nanoparticles.

Properties	Graphite
Average particle size (nm)	35
Density (at 20°C) (g/cm³)	2
Purity (%)	99.9
Specific surface area (m²/g)	180

Table 2.

Properties of base fluids.

Properties	Deionized water	LB2000 vegetable-based oil
Appearance	–	Dark blue fluid
Density (at 20°C) (g/cm³)	0.99987	0.92
Flash point (°C)	–	320
Pour point (°C)	–	−20

Graphite nanofluids were prepared by adding a certain amount of graphite nanoparticles to base fluids followed by sonification (40 kHz, 100 W). The concentration of graphite nanoparticles in base fluids is 0.5 wt%. The ultrasonication time employed was 1.0 h for all of the nanofluids prepared. The stability of graphite nanofluids was checked using sedimentation method. The results show that the graphite water-based nanofluid prepared was found to be stable for 2.5 h after which the sedimentation started, while the graphite oil-based nanofluid prepared remained stable for more than 3 months without any visible sedimentation.

Figure 2 shows the electrostatic atomization characterization apparatus schematically. It consists of the experimental setup of electrostatic atomization and a vision module. In the experimental setup of electrostatic atomization, the nozzle is made of stainless steel and its section is shown in Figure 3. The nozzle is held in adjustable unit so that different values of its angle θ ₁ and θ ₂ are obtained. As shown in Figure 4, nozzle angle θ ₁ and θ ₂ refer to the angle between nozzle and YZ plane, and that between nozzle and XY plane (rake face), respectively. Electrode distance h is the distance between outlet of nozzle and rake face of tool along the axis of nozzle. The adjustable unit is made of polyformaldehyde so as to ensure that the nozzle is properly isolated electrically. The nozzle is connected to ZGY-5 negative high voltage power supply (Dalian Power Supply Technology Co., Ltd, China), which can supply a maximum voltage of −120 kV. As counter electrode, the equilateral triangular indexable insert made of uncoated cemented carbide, which is procured from the company Walter AG, is mounted on a mechanical stage and connected to the ground. By changing the height of mechanical stage, the height of cutting insert is adjustable in order to achieve different electrode distances conveniently. The stable graphite water-based and oil-based nanofluids prepared are used as the atomization fluids in the experiments. The properties of fluid such as dynamic viscosity, conductivity, relative permittivity, and surface tension influence the electrostatic atomization of fluid. Thus, significant knowledge about these physical properties of nanofluids is required. The dynamic viscosity of graphite water-based and oil-based nanofluids prepared is measured by a rotational-type viscometer (NDJ-9S, Shanghai Fangrui Instrument Co., Ltd, China). A BZY-1 automatic surface tension meter, produced by Shanghai Precision Instrument Co., Ltd, is used for surface tension measurements of nanofluids. The conductivity and relative permittivity of nanofluids prepared are measured with a LCR-meter model 4285A from Agilent. The maximum deviation is found to be less than 5% in the measurements of these properties. The measured physical properties of both nanofluids are presented in Table 3. The inlet of nozzle is connected to a LSP01-1A syringe pump with maximum error of 0.5% (Baoding Longer Precision Pump Co., Ltd, China) using a silicone rubber tube, allowing the flow rate of nanofluids to the nozzle to be varied between 3.33 μL/min and 43.35 mL/min.

Figure 2.

Schematic diagram of electrostatic atomization characterization apparatus.

Figure 3.

Section of nozzle.

Figure 4.

Illustration of nozzle angle and electrode distance.

Table 3.

Physical properties of graphite nanofluids.

Properties	Graphite water-based nanofluid	Graphite oil-based nanofluid
Dynamic viscosity (mPa s)	7.5	56.0
Conductivity (S/m)	1.99 × 10⁻³	3.1 × 10⁻⁷
Relative permittivity	83.53	2.55
Surface tension (mN/m)	49.3	29.53

The dynamic electrostatic atomization process is observed and recorded using the vision module that consists of a high-speed digital camera (FASTCAM- Super-10 KC, Photron, Japan), a zoom lens AF Micro-Nikkor (60 mm, f/2.8D), a light-emitting diode (LED) source, and a computer containing a video interface. The zoom lens attached to the high-speed camera is used as a focusing and zoom optical system. The LED light source is located behind the nozzle to illuminate the region between the nozzle and the cutting insert. The following settings are kept for all measurements: 1000 fps (frames per second) and resolution of 48 ppi (pixel per inch). The experimental conditions used in electrostatic atomization are given in Table 4. In metal cutting, the angle of nozzle has an important effect on the cooling/lubricating performance of cooling/lubricating method. Furthermore, the electrostatic field intensity is influenced by the angle of nozzle relative to cutting insert. Thus, different values of nozzle angle are used in electrostatic atomization experiments to study the effect of nozzle angle on the electrostatic atomization behavior.

Table 4.

Experimental conditions used in electrostatic atomization.

Experimental parameters	Values
Nozzle angle, θ ₁ (°)	0, 30, 60
Nozzle angle, θ ₂ (°)	35, 45, 65
Electrode voltage, U (kV)	0−(−25)
Flow rate, q (mL/min)	0.42, 1.0, 1.5, 2.5
Electrode distance, h (mm)	20, 30
Inner and outer diameter of nozzle, d/D (mm)	0.4/0.7
Length of nozzle, L (mm)	10

Three-dimensional finite element model of electrostatic field between nozzle and cutting tool

Geometry and meshing

Based on the electrostatic atomization experiments, the nozzle and cutting insert are modeled using three-dimensional (3D) drawing software Pro/Engineer, and then imported to the software Ansoft Maxwell which is used to analyze the electromagnetic field, as shown in Figure 5. The inside and surface of rectangle frame containing the nozzle and cutting insert is solving region. The nozzle, cutting insert, and solving region are meshed with adaptive mesh generation. Figure 6 shows the mesh configuration of them.

Figure 5.

Geometric model.

Figure 6.

Mesh configuration: (a) nozzle and cutting insert and (b) solving region.

Materials properties and boundary conditions

The nozzle and tool material used in this model are stainless steel and cemented carbide, respectively. The material of solving region is air. The physical properties of nozzle, tool, and solving region are given in Table 5. According to the concept of electrostatic atomization cutting, negative high voltage and 0 kV are assigned to nozzle and tool, respectively.

Table 5.

Material properties.

Name	Material	Conductivity (S/m)	Relative permittivity
Tool	Cemented carbide	5,882,353	1.0
Nozzle	Stainless steel	1,100,000	1.0
Solving region	Air	0	1.0006

Finite element analysis

In order to analyze the effect of electrostatic field on the electrostatic atomization mode, the values of nozzle angle θ ₁ and θ ₂, electrode voltage U, and electrode distance h defined in the simulations are the same as those defined in the experiments.

Evaluation of electrostatic field intensity

The predicted distributions of electrostatic field intensity and power line vector are shown in Figure 7. The maximum electrostatic field intensity between nozzle and cutting insert is indicated in both distributions. Besides it, the electrostatic field intensity at specified line can also be obtained from the simulation. For example, line 1 is a straight line with a length of 20 mm that is from the outlet of nozzle to the rake face of cutting insert along the axis of nozzle (Figure 8(a)). Figure 8(b) shows the variation of electrostatic field intensity at line 1 with the distance from the outlet of nozzle. It can be seen that the electrostatic field intensity distributes nonuniformly at line 1. High electrostatic field intensity localizes near the outlet of nozzle, as shown in Figure 8(b). The average value of electrostatic field intensity at line 1 may be calculated according to simulation results.

Figure 7.

Predicted distributions of electrostatic field intensity and power line vector: (a) electrostatic field intensity and (b) power line vector.

Figure 8.

Variation of electrostatic field intensity at line 1 with the distance from the outlet of nozzle: (a) line 1 and (b) electrostatic field intensity.

During the post-processing, five lines (lines 1–5) with a length of 1 mm are specified at the outlet of nozzle (Figure 9). As shown in Figure 9, line 1 coincides with the axis of nozzle, and the left lines are parallel to the axis of nozzle. The lines 2–5 distribute homogeneously on the cylindrical surface with axis at line 1 and radius equal to 0.1 mm. The average value of electrostatic field intensity at specified line is defined as the electrostatic field intensity of specified line. Moreover, the average value of the electrostatic field intensity of five specified lines is calculated and used to evaluate the electrostatic field intensity under different operating conditions. For effective evaluation, the position of five lines changes with the change in nozzle angle.

Figure 9.

Distribution of specified five lines.

Results and discussion

Influence of electrode voltage on the electrostatic atomization mode

There are a wide variety of atomization modes in the electrostatic atomization process. The specific atomization mode depends on the electrostatic field intensity, fluid properties, and flow rate. The electrostatic field intensity is dependent on the electrode voltage and distance, the geometry of nozzle and ground electrode, and the angle of nozzle relative to ground electrode. Thus, electrode voltage is an important parameter that significantly influences the electrostatic atomization mode. Figures 10 and 11 show the variation of electrostatic atomization mode of graphite water-based and oil-based nanofluids with electrode voltage, respectively. When no voltage is applied at the nozzle, the drop is kept connected to main nanofluid body in the nozzle due to surface tension. Once the gravitational force of drop exceeds the surface tension, the regular rounded shape of nanofluid droplet with a large diameter separates from the end of nozzle. The drop frequency of graphite oil-based nanofluid is lower than that of graphite water-based nanofluid because of its higher viscosity. As the electrode voltage is increased, the drop frequency increases and the diameter decreases (Figure 10(a) and (b)), regardless of the type of nanofluid used. This is because the electrostatic force assists the gravitational force in detaching droplets. This mode described above is referred to as the dripping mode (Figures 10(a) and (b) and 11(a)). When the electrode voltage exceeds a certain critical value, the meniscus at the outlet of nozzle is elongated to a spindle-like shape by electrostatic force and contracts to a hemispherical shape after the detachment of spindle-like fragment of nanofluid. This is described in the literature¹² as a spindle mode of electrostatic atomization. The spindle becomes shorter as the electrode voltage increases, as shown in Figures 10(d) and (e) and 11(d) and (e). In case of electrostatic atomization of graphite oil-based nanofluid, a further increase in electrode voltage results in the multi-spindle mode (Figure 11(c), (f), (h), and (i)) in which several short spindle-like jets are ejected simultaneously from the circumference of the nozzle. It can be seen from Figure 11(h) and (i) that the number of these jets and spray angle increase with the increase in electrode voltage. In case of electrostatic atomization of graphite water-based nanofluid, when the electrode voltage is increased further, a jet breaks into two spindle-like fragments at the cone apex (Figure 10(f)), which is also called as multi-spindle mode here, or a jet oscillates in the plane of nozzle axis (Figure 10(h) and (i)), which corresponds to oscillating-jet mode according to the literature.¹² The initial oscillation with low amplitude can be observed at the outlet of nozzle in the oscillating-jet mode, and the amplitude of oscillation increases with a decrease in jet diameter because of the law of momentum conservation.

Figure 10.

Variation of electrostatic atomization mode of graphite water-based nanofluid with electrode voltage ((a)–(c): θ ₁ = 0°, θ ₂ = 65°, q = 0.42 mL/min, h = 20 mm; (d)–(f): θ ₁ = 60°, θ ₂ = 35°, q = 1.0 mL/min, h = 30 mm; (g)–(i): θ ₁ = 30°, θ ₂ = 65°, q = 2.5 mL/min, h = 30 mm): (a) −5.2 kV (dripping), (b) −10 kV (dripping), (c) −14.2 kV (spindle), (d) −10 kV (spindle), (e) −12.7 kV (spindle), (f) −14.3 kV (multi-spindle), (g) −10 kV (spindle), (h) −15.3 kV (oscillating), and (i) −19.4 kV (oscillating).

Figure 11.

Variation of electrostatic atomization mode of graphite oil-based nanofluid with electrode voltage ((a)–(c): θ ₁ = 60°, θ ₂ = 45°, q = 1.0 mL/min, h = 20 mm; (d)–(f): θ ₁ = 30°, θ ₂ = 65°, q = 0.42 mL/min, h = 30 mm; (g)–(i): θ ₁ = 30°, θ ₂ = 65°, q = 1.0 mL/min, h = 30 mm): (a) −6.8 kV (dripping), (b) −10 kV (spindle), (c) −12.2 kV (multi-spindle), (d) −10 kV (spindle), (e) −13.8 kV (spindle), (f) −18.3 kV (multi-spindle), (g) −12 kV (spindle), (h) −16.2 kV (multi-spindle), and (i) −19.1 kV (multi-spindle).

In order to study the effect of electrode voltage on the electrostatic atomization mode, the electrostatic field under the conditions of Figures 10 and 11 is analyzed. Figure 12 shows the variation of the difference of electrostatic field intensity for specified lines with electrode voltage. As shown in Figure 12, the difference in the electrostatic field intensity between line 2 and line 4, and that between line 3 and line 5 increase with the electrode voltage increasing, regardless of nozzle angle and electrode distance employed, indicating more nonuniform distribution of electrostatic field at the outlet of nozzle. The great inhomogeneity of electrostatic field at high electrode voltage results in the generation of multi-spindle and oscillating-jet modes to a large extent.

Figure 12.

Variation of the difference of electrostatic field intensity for specified lines with electrode voltage: (a) θ ₁ = 0°, θ ₂ = 65°, h = 20 mm; (b) θ ₁ = 60°, θ ₂ = 35°, h = 30 mm; (c) θ ₁ = 30°, θ ₂ = 65°, h = 30 mm; and (d) θ ₁ = 60°, θ ₂ = 45°, h = 20 mm.

In dripping mode, the droplets with large size generated cannot reach the cutting edge due to the low electrostatic field intensity. Although small droplets may be achieved in multi-spindle or oscillating-jet mode owing to the high electrostatic field intensity, they cannot localize at the cutting zone, failing to cool and lubricate the cutting edge effectively. Compared with the atomization modes mentioned above, spindle mode seems to be suitable electrostatic atomization mode for cooling and lubricating the cutting edge because of the droplets’ relatively small size and defined direction of motion.

Influence of nozzle angle on the electrostatic atomization mode

Figures 13 and 14 show the effect of nozzle angles θ ₁ and θ ₂ on the spindle mode, respectively. As can be seen clearly, good break-up effect of jet can be obtained with an increase in θ ₁ and a decrease in θ ₂. Figures 15 and 16 show the variation of electrostatic field intensity at the outlet of nozzle with nozzle angles θ ₁ and θ ₂, respectively. It can be seen that an increase in θ ₁ and a decrease in θ ₂ lead to the increase in electrostatic field intensity. This may be the reason why good break-up effect of jet can be achieved using a large nozzle angle θ ₁ and a small nozzle angle θ ₂ (Figures 13 and 14). As shown in Figures 15 and 16, nozzle angles θ ₁ = 60° and θ ₂ = 35° provide the largest electrostatic field intensity at the outlet of nozzle, which is beneficial to generate small-sized droplets in the spindle mode. The trajectories of droplets change with the flow rate of graphite nanofluids employed, especially at high flow rates. Thus, droplets are likely to be exposed to different physical locations of the electrostatic field. Therefore, the optimal nozzle angle for cooling and lubricating the cutting edge in the spindle mode has to be further determined for each flow rate of graphite nanofluids used.

Figure 13.

Spindle mode of graphite water-based nanofluid under different nozzle angle θ ₁ (θ ₂ = 45°, U = −10 kV, q = 1.0 mL/min, h = 30 mm): (a) θ ₁ = 30° and (b) θ ₁ = 60°.

Figure 14.

Spindle mode of graphite oil-based nanofluid under different nozzle angle θ ₂ (θ ₁ = 60°, U = −13 kV, q = 1.0 mL/min, h = 30 mm): (a) θ ₂ = 35° and (b) θ ₂ = 65°.

Figure 15.

Variation of electrostatic field intensity at the outlet of nozzle with nozzle angle θ _1.

Figure 16.

Variation of electrostatic field intensity at the outlet of nozzle with nozzle angle θ _2.

Operating range of electrostatic atomization modes

For fixed geometric and a liquid of given properties, electrostatic atomization mode changes from one to another with the changes in the electrode voltage and the flow rate of the liquid. Figures 17 and 18 show the operating range of electrostatic atomization modes in terms of the electrode voltage and flow rate for graphite water-based and oil-based nanofluid, respectively. As shown in Figure 17, the top and bottom curves represent the maximum and minimum voltage at which spindle mode can be operated, respectively. It can be found from Figure 17 that the threshold voltage for changing the spindle mode to the multi-spindle or oscillating-jet mode decreases with the flow rate increasing. This may be attributed to good charge performance of graphite water-based nanofluid and the repulsive action of higher surface charge on the jet due to the higher currents caused by the high flow rate. As shown in Figure 18, only the minimum voltage at which spindle mode is in operation is provided for graphite oil-based nanofluid because in the current range of electrode voltage and flow rate applied, multi-spindle mode does not appear. According to Figures 17 and 18, the operating parameters such as electrode voltage and flow rate can be selected to cool and lubricate the cutting edge in spindle mode under the nozzle angle with the largest electrostatic field intensity (θ ₁ = 60°, θ ₂ = 35°).

Figure 17.

Operating range of atomization modes for graphite water-based nanofluid (θ ₁ = 60°, θ ₂ = 35°): (a) h = 20 mm and (b) h = 30 mm.

Figure 18.

Operating range of atomization modes for graphite oil-based nanofluid (θ ₁ = 60°, θ ₂ = 35°): (a) h = 20 mm and (b) h = 30 mm.

Conclusion

In this article, experiments were performed on the developed electrostatic atomization setup in order to observe and analyze the atomization modes of graphite water-based and oil-based nanofluids under different operating conditions such as electrode voltage, flow rate, electrode distance, and nozzle angle, and the electrostatic field between nozzle and cutting tool was analyzed using 3D finite element (FE) simulation. From the experiments of atomization mode and the numerical simulations of electrostatic field, the following conclusions can be reached:

With the electrode voltage increasing, the electrostatic atomization of graphite water-based nanofluid goes through dripping mode, spindle mode, and multi-spindle mode or oscillating-jet mode; the electrostatic atomization of graphite oil-based nanofluid successively takes on dripping mode, spindle mode, and multi-spindle mode. Among the electrostatic atomization modes generated, spindle mode is relatively suitable for cooling and lubricating the cutting edge.

The electrostatic field at the outlet of nozzle becomes more and more nonuniform with an increase in electrode voltage. The generation of multi-spindle and oscillating-jet modes is highly dependent on the nonuniform distribution of electrostatic field at high electrode voltage.

Increasing nozzle angle θ ₁ and decreasing nozzle angle θ ₂ result in an increase in the electrostatic field intensity, thus generating good break-up effect of jet. The largest electrostatic field intensity can be obtained under θ ₁ = 60° and θ ₂ = 35°, which is beneficial to make the jet better break up in spindle mode. But the optimal nozzle angle needs to be further determined for each flow rate of graphite nanofluids employed, due to the fact that the droplets are likely to be exposed to different physical locations of the electrostatic field owing to the change in their trajectories when the flow rate used varies.

The range of electrode voltage and flow rate, in which spindle mode operates, is achieved. It is helpful for selecting the operating parameters to cooling and lubricating the cutting edge in spindle mode.

In further study, the droplets’ size and velocity will be measured in spindle mode so that the operating parameters can be further optimized for cooling and lubricating the cutting edge more effectively.

Footnotes

Handling Editor: Kang Cheung Chan

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research,authorship,and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research,authorship,and/or publication of this article: This work was supported by National Natural Science Foundation of China under contract nos. 51205177 and 51305174,Natural Science Foundation of Jiangsu Province under contract nos. BK2012277 and BK20171307,Natural Science Program for Basic Research of Jiangsu Province under contract no. 08KJB460002,Qing Lan Project,and Research Fund of DML-HYIT (HGDML-0901).

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An investigation on the electrostatic atomization mode of nanofluid using cutting tool as electrode