Experimental study on atomization characteristics and particle size prediction of gas-liquid coaxial swirl injector

doi:10.11949/0438-1157.20250279

Abstract

Abstract:

Liquid-centered swirl coaxial injectors can effectively increase the specific surface area of droplets and enhance the atomization effect, which is widely used in industrial technology. In this research, an experimental work was presented on the contribution of the aerodynamic effect (air assisting or not) and operating factors (liquid pressure, gas pressure and gas-liquid ratio) on droplet size distribution generated by single-fluid swirl nozzles and liquid-centered swirl coaxial (LCSC) injectors. The stable operating conditions were clarified, which could avoid the deterioration of atomization effect caused by pressure fluctuations during operation. The results show that, unlike the single-peak distribution of swirl nozzles, the droplet size distribution of coaxial gas-liquid centrifugal nozzles exhibits a bimodal distribution, and gas shear force significantly improves the atomization performance. When the gas-liquid outlet area ratio is 48, operating in gas pressure of 0.25 MPa and liquid pressure of 0.6 MPa, Sauter mean diameter (SMD) reaches a minimum of 36.5 μm, which is 84.3% lower than that without air assisting. Moreover, LCSC injectors can reduce the atomization dependence on operating pressure. When the gas pressure is over 0.1 MPa and gas-liquid ratio is over 0.28, SMD will be not sensitive to the liquid pressure. An empirical correlation for both single-fluid swirl nozzles and LCSC injectors is developed by dimensional analysis to predict the atomization droplet size. It is expected to improve the atomization efficiency, and reduce pressure dependence during operation.

Key words: gas-liquid coaxial swirl injector, atomization characteristic, size distribution, dimensional analysis

摘要：

气液同轴离心喷嘴利用气体剪切作用获得良好的雾化效果，广泛应用于工业生产当中。实验研究了气体剪切作用（有无空气助力）以及运行条件对气液同轴喷嘴雾化特性的影响，明确了稳定运行工况，解决运行压力波动导致雾化效果恶化的问题。结果表明，与旋流喷嘴的单峰分布不同，气液同轴离心喷嘴的雾化粒径分布具有双峰分布的特点，气体剪切作用显著提高了喷嘴的雾化效果。当气液出口面积比为48，气体压力为0.25 MPa，液体压力为0.6 MPa时，索特平均直径（SMD）最小可达到36.5 μm，比没有空气助力的情况降低了84.3%。此外，当气体压力超过0.1 MPa，气液比超过0.28时，SMD不随液体压力变化，可以减少雾化效果对运行压力的依赖。最后通过量纲分析，建立了旋流喷嘴和气液同轴离心喷嘴雾化粒径的经验关联式，对雾化效果实现精准预测。

关键词: 气液同轴离心喷嘴, 雾化特性, 粒径分布, 量纲分析

CLC Number:

TK 124

Peiwen DONG, Guoqiang LIU, Gang YAN. Experimental study on atomization characteristics and particle size prediction of gas-liquid coaxial swirl injector[J]. CIESC Journal, 2025, 76(11): 5865-5876.

董佩文, 刘国强, 晏刚. 气液同轴离心喷嘴雾化特性实验研究及粒径预测[J]. 化工学报, 2025, 76(11): 5865-5876.

Figures/Tables 14

Fig.1 Experimental platform for testing the atomization characteristics of artificial snowmaking

Table 1 Equipment parameters

设备	品牌型号	参数	不确定度
水泵	CNP CDL(F)2-15	最大扬程：134 m；额定流量： 2 t·h^-1	—
空压机	芝浦ZP-KYJ-002	压力范围：0.05~0.25 MPa；排量: 0.27 m³·min^-1	—
气体流量计	美控LUGB-C-DN15	测量范围：3~10 m³·h^-1	±1.5%FS
激光粒度仪	NKT PW180-B	测量范围：0.1~1000 μm	±0.5%FS

Fig.2 Nozzle structure

Table 2 Nozzle structure parameters

喷嘴标号	气体出口环形内直径 $D g, i$ /mm	气体出口环形外直径 $D g, o$ /mm	液体出口直径 $D l$ /mm	$S g / S l$
W8-0.5 A4-1	2.0	4.0	0.5	48
W8-0.5 A4-0.5	2.5	3.5	0.5	24
W8-1 A4-1	2.0	4.0	1.0	12
W8-1 A4-0.5	2.5	3.5	1.0	6
W8-1.5 A4-1	2.0	4.0	1.5	5.33
W8-1.5 A4-0.5	2.5	3.5	1.5	2.67

Table 2 Nozzle structure parameters

喷嘴标号	气体出口环形内直径 $D g, i$ /mm	气体出口环形外直径 $D g, o$ /mm	液体出口直径 $D l$ /mm	$S g / S l$
W8-0.5 A4-1	2.0	4.0	0.5	48
W8-0.5 A4-0.5	2.5	3.5	0.5	24
W8-1 A4-1	2.0	4.0	1.0	12
W8-1 A4-0.5	2.5	3.5	1.0	6
W8-1.5 A4-1	2.0	4.0	1.5	5.33
W8-1.5 A4-0.5	2.5	3.5	1.5	2.67

Table 3 Accuracy testing of nozzles

喷嘴	样品	索特平均粒径SMD/μm	气体流量/（L·min^-1）	液体流量/（L·min^-1）
W8-1.5 A4-1	1	78.98	300	2.13
	2	80.97	294	2.16
	3	77.56	298	2.08
标准偏差		0.80	4.29	0.045

Fig.3 Droplet size distribution of swirl nozzle（W8-1 A4-0.5）

Fig.4 Sauter mean diameter of swirl nozzle（Sg/Sl=6）

Fig.5 Droplet size distribution of gas-liquid coaxial nozzle

Fig.6 Sauter mean diameter under different nozzle structures

Fig.7 Sauter mean diameter varying with gas-liquid mass flow ratio

Table 4 Dimensional analysis variables

变量	基本物理量
变量	质量	长度	时间
气体质量流量 $M g$	1	0	-1
液体质量流量 $M l$	1	0	-1
气体出口面积 $S g$	0	2	0
液体出口面积 $S l$	0	2	0
气体密度 $ρ g$	1	-3	0
液体密度 $ρ l$	1	-3	0
液体表面张力 $σ l$	1	0	-2
液体黏度 $μ l$	1	-1	-1
液体压力 $P l$	1	-1	-2

Table 4 Dimensional analysis variables

变量	基本物理量
变量	质量	长度	时间
气体质量流量 $M g$	1	0	-1
液体质量流量 $M l$	1	0	-1
气体出口面积 $S g$	0	2	0
液体出口面积 $S l$	0	2	0
气体密度 $ρ g$	1	-3	0
液体密度 $ρ l$	1	-3	0
液体表面张力 $σ l$	1	0	-2
液体黏度 $μ l$	1	-1	-1
液体压力 $P l$	1	-1	-2

Table 5 The coefficient values of Eq. （7）

模型系数	单流体喷嘴	气液同轴喷嘴
模型系数	单流体喷嘴	$S g / S l$ =48	$S g / S l$ =24	$S g / S l$ =12	$S g / S l$ =6	$S g / S l$ =5.33	$S g / S l$ =2.67
$k 1$	-15.48	5.93×10⁴	3.06×10⁴	70.85	7.37×10⁷	2.38×10⁴	0.046
$a 1$	—	-0.19	1.56	8.39	-23.39	0.84	48.61
$b 1$	—	0.060	0.39	3.75	9.54	1.10	-4.20
$c 1$	—	-0.035	-0.19	-1.43	-1.37	-0.28	0.63
$d 1$	-2.49	0.91	0.040	-0.21	-42.63	-0.12	18.02
$k 2$	2.73×10⁷	1.75×10⁸	3.33×10⁴	1.19×10⁵	695.27	8.57×10¹⁰	3.65×10⁵
$a 2$	—	-5.29	-2.76	-1.52	-1.50	-26.32	-3.33
$b 2$	—	2.26	1.36	0.47	4.96	9.96	2.19
$c 2$	—	-1.35	-0.64	-0.18	-0.089	-2.61	-0.33
$d 2$	-0.61	-1.12	-0.13	0.0033	0.88	5.32	-0.10
$e$	0.83	0.026	-0.32	-2.16	1.39	-0.33	-1.24
$f$	-0.43	-2.38	-0.69	-0.24	-0.51	-5.45	-0.52

Table 5 The coefficient values of Eq. （7）

模型系数	单流体喷嘴	气液同轴喷嘴
模型系数	单流体喷嘴	$S g / S l$ =48	$S g / S l$ =24	$S g / S l$ =12	$S g / S l$ =6	$S g / S l$ =5.33	$S g / S l$ =2.67
$k 1$	-15.48	5.93×10⁴	3.06×10⁴	70.85	7.37×10⁷	2.38×10⁴	0.046
$a 1$	—	-0.19	1.56	8.39	-23.39	0.84	48.61
$b 1$	—	0.060	0.39	3.75	9.54	1.10	-4.20
$c 1$	—	-0.035	-0.19	-1.43	-1.37	-0.28	0.63
$d 1$	-2.49	0.91	0.040	-0.21	-42.63	-0.12	18.02
$k 2$	2.73×10⁷	1.75×10⁸	3.33×10⁴	1.19×10⁵	695.27	8.57×10¹⁰	3.65×10⁵
$a 2$	—	-5.29	-2.76	-1.52	-1.50	-26.32	-3.33
$b 2$	—	2.26	1.36	0.47	4.96	9.96	2.19
$c 2$	—	-1.35	-0.64	-0.18	-0.089	-2.61	-0.33
$d 2$	-0.61	-1.12	-0.13	0.0033	0.88	5.32	-0.10
$e$	0.83	0.026	-0.32	-2.16	1.39	-0.33	-1.24
$f$	-0.43	-2.38	-0.69	-0.24	-0.51	-5.45	-0.52

Fig.8 Comparison between experimental results and model prediction results

Table A1 Experimental results of gas-liquid coaxial nozzle

喷嘴编号	液体压力 $P l$ /MPa	液体流量/(L·min^-1)	液体速度/(m·s^-1)	气体压力 $P g$ /MPa	气体流量/(L·min^-1)
喷嘴Ⅰ	0.6	0.33	28.01	0.05	100
	0.8	0.35	30.05	0.10	150
	1.0	0.45	38.20	0.15	200
	1.2	0.47	40.23	0.20	250
	1.4	0.50	42.27	0.25	300
喷嘴Ⅱ	0.6	0.33	28.01	0.05	45
	0.8	0.35	30.05	0.10	90
	1.0	0.45	38.20	0.15	130
	1.2	0.47	40.23	0.20	180
	1.4	0.50	42.27	0.25	215
喷嘴Ⅲ	0.6	0.72	15.28	0.05	100
	0.8	0.78	16.55	0.10	150
	1.0	0.85	17.95	0.15	200
	1.2	0.94	19.99	0.20	250
	1.4	1.03	21.90	0.25	300
喷嘴Ⅳ	0.6	0.72	15.28	0.05	45
	0.8	0.78	16.55	0.10	90
	1.0	0.85	17.95	0.15	130
	1.2	0.94	19.99	0.20	180
	1.4	1.03	21.90	0.25	215
喷嘴Ⅴ	0.6	1.38	13.02	0.05	100
	0.8	1.57	14.77	0.10	150
	1.0	1.76	16.58	0.15	200
	1.2	1.95	18.39	0.20	250
	1.4	2.13	20.09	0.25	300
喷嘴Ⅵ	0.6	1.38	13.02	0.05	45
	0.8	1.57	14.77	0.10	90
	1.0	1.76	16.58	0.15	130
	1.2	1.95	18.39	0.20	180
	1.4	2.13	20.09	0.25	215

Table A1 Experimental results of gas-liquid coaxial nozzle

喷嘴编号	液体压力 $P l$ /MPa	液体流量/(L·min^-1)	液体速度/(m·s^-1)	气体压力 $P g$ /MPa	气体流量/(L·min^-1)
喷嘴Ⅰ	0.6	0.33	28.01	0.05	100
	0.8	0.35	30.05	0.10	150
	1.0	0.45	38.20	0.15	200
	1.2	0.47	40.23	0.20	250
	1.4	0.50	42.27	0.25	300
喷嘴Ⅱ	0.6	0.33	28.01	0.05	45
	0.8	0.35	30.05	0.10	90
	1.0	0.45	38.20	0.15	130
	1.2	0.47	40.23	0.20	180
	1.4	0.50	42.27	0.25	215
喷嘴Ⅲ	0.6	0.72	15.28	0.05	100
	0.8	0.78	16.55	0.10	150
	1.0	0.85	17.95	0.15	200
	1.2	0.94	19.99	0.20	250
	1.4	1.03	21.90	0.25	300
喷嘴Ⅳ	0.6	0.72	15.28	0.05	45
	0.8	0.78	16.55	0.10	90
	1.0	0.85	17.95	0.15	130
	1.2	0.94	19.99	0.20	180
	1.4	1.03	21.90	0.25	215
喷嘴Ⅴ	0.6	1.38	13.02	0.05	100
	0.8	1.57	14.77	0.10	150
	1.0	1.76	16.58	0.15	200
	1.2	1.95	18.39	0.20	250
	1.4	2.13	20.09	0.25	300
喷嘴Ⅵ	0.6	1.38	13.02	0.05	45
	0.8	1.57	14.77	0.10	90
	1.0	1.76	16.58	0.15	130
	1.2	1.95	18.39	0.20	180
	1.4	2.13	20.09	0.25	215

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