Vibration characteristics of the flexible-blade Rushton impeller

doi:10.11949/0438-1157.20201151

Abstract

Abstract:

In this paper, vibration characteristics of the bench-scale flexible-blade Rushton impeller developed by our team previously were numerically studied. Experimental measurements using the Denmark Brüel & Kj?r and China Donghua vibration testing instruments were also carried out. It was found that the 1st to 6th and the 7th to 12th-order vibration mode of the flexible-blade impeller and shaft system was the bending and torsional type, respectively. The simulated natural frequencies agree well with the experimental results, both indicate the existence of frequency concentrating phenomenon. Compared with the dry-modal natural frequencies, the wet-modal natural frequencies are decreased. When exerted high-frequency alternating excitation load, there is clear stress and strain harmonic responses. Natural frequency of this system decreases with the increase of impeller rotational speed, and increases with the increase of fluid viscosity. The research results lay the foundation for the enlarged design and industrial application of flexible blade Rushton impeller.

Key words: stirred vessel, flexible-blade Rushton impeller, vibration characteristics, numerical simulation, experimental validation

摘要：

采用数值模拟的方法分析了课题组前期开发的实验室规模的柔性叶片Rushton搅拌桨的振动特性，并采用丹麦的Brüel & Kj?r及中国的东华振动测试仪进行了实验研究。结果表明，桨轴系统的第1~6阶振型为弯曲型，第7~12阶振型为扭转型。模拟得到的固有频率与实验结果吻合较好，均表明存在集聚现象；与干模态固有频率相比，湿模态固有频率有所降低。承受高频交变激励载荷时，桨轴系统存在明显的应力和应变谐响应。桨轴系统的固有频率随转速的增大而减小，随介质黏度的增大而增大。研究结果为柔性叶片Rushton搅拌桨的放大设计及工业应用奠定了基础。

关键词: 搅拌容器, 柔性Rushton搅拌桨, 振动特性, 数值模拟, 实验验证

CLC Number:

TQ 027

YANG Fengling, CAO Mingjian, ZHANG Cuixun, LIU Xin. Vibration characteristics of the flexible-blade Rushton impeller[J]. CIESC Journal, 2021, 72(4): 1975-1986.

杨锋苓, 曹明见, 张翠勋, 刘欣. 柔性Rushton搅拌桨的振动特性[J]. 化工学报, 2021, 72(4): 1975-1986.

Figures/Tables 20

References 30

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搅拌介质	密度ρ/ (kg·m^-3)	黏度μ/ (Pa·s)	转速N/ s^-1	Reynolds数 (Re=ρNd²/μ)
水	998.20	0.001	1~5	22500~112500
70%甘油	1183.77	0.023	2	2367
80%甘油	1210.28	0.060	2	906
90%甘油	1236.79	0.219	2	254
100%甘油	1263.30	1.412	2	40

搅拌介质	密度ρ/ (kg·m^-3)	黏度μ/ (Pa·s)	转速N/ s^-1	Reynolds数 (Re=ρNd²/μ)
水	998.20	0.001	1~5	22500~112500
70%甘油	1183.77	0.023	2	2367
80%甘油	1210.28	0.060	2	906
90%甘油	1236.79	0.219	2	254
100%甘油	1263.30	1.412	2	40

网格密度	网格尺寸		网格数量/个	网格质量
网格密度	静子	转子	网格数量/个	网格质量
coarse	5	4	458811	0.86
medium	4	3	950124	0.89
fine	3.8	2.8	1142299	0.89

网格密度	网格尺寸		网格数量/个	网格质量
网格密度	静子	转子	网格数量/个	网格质量
coarse	5	4	458811	0.86
medium	4	3	950124	0.89
fine	3.8	2.8	1142299	0.89

阶数	干模态频率/Hz	湿模态频率/Hz	下降比例/%
1	24.811	24.210	2.42
2	24.811	24.211	2.42
3	24.811	24.218	2.39
4	24.812	24.232	2.34
5	24.812	24.244	2.29
6	24.812	24.253	2.25
7	84.536	82.707	2.16
8	84.536	82.720	2.15
9	84.536	82.742	2.12
10	84.536	82.745	2.12
11	84.536	82.771	2.09
12	84.537	82.804	2.05
13	150.280	149.580	0.47
14	150.280	149.600	0.45
15	150.380	149.690	0.46
16	150.420	149.730	0.46
17	150.420	149.730	0.46
18	150.420	149.750	0.45
19	189.540	189.500	0.02
20	189.540	189.500	0.02
21	190.050	190.010	0.02
22	190.290	190.250	0.02
23	190.290	190.250	0.02
24	190.590	190.560	0.02