# 超声空化对污垢沉积特性影响的数值研究

(东北电力大学能源与动力工程学院，吉林省 吉林市 132012)

## 引 言

P(t)=P1+P2sin(2πft)

(1)

## 1 研究对象的物理模型及网格划分

1.1 物理模型

Fig.1 Physical model

1.2 网格划分

Fig.2 Mesh generation of physical model

## 2 数学模型及边界条件

2.1 数学模型

(2)

2.2 污垢沉积模型

(3)

(4)

=-

(5)

Rf=mf/(ρfλf)

(6)

2.3 边界条件

Table 1 Simulation conditions

## 3 数值方法与验证

Fig.3 Verifying grid independence about fouling resistance

Fig.4 Comparison between experiment and simulation result

Table 2 Computational error rate at various Reynolds numbers

## 4 计算结果与分析

4.1 不同入口速度下超声空化对污垢剥蚀的影响

Fig.5 Net deposition rate and its correction for theoretical and numerical results

Fig.6 Effect of ultrasonic cavitation on removal rate at different inlet velocity

4.2 不同频率下超声空化对污垢剥蚀的影响

Fig.7 Effect of ultrasonic cavitation on removal rate at different ultrasonic frequencies

4.3 超声波频率对污垢沉积特性的影响

Fig.8 Fouling deposition characteristic at different ultrasonic frequencies

4.4 误差分析

Fig.9 Relative error between numerical values and experimental values

## 5 结 论

(1)防除垢超声波在一定频率下，增加换热管内流体速度，超声空化效果减弱，超声空化对污垢的剥蚀效果减小，本文流速为0.37 m·s-1时的剥蚀率大于0.74 m·s-1的剥蚀率，所以在以上两种流速可供选择的情况下，可以选择0.37 m·s-1的流速来提高超声空化的防除垢效果。

(2)超声波具有明显的防除垢效果，超声空化会增大污垢的剥蚀，减小沉积，降低壁面的热阻。在流速一定条件下，增大超声波频率，超声空化对污垢的剥蚀降低，本文中频率为20 kHz的超声波空化效果好，对污垢的剥蚀效果较40 kHz的超声波显著，热阻及净沉积率也小于频率为40 kHz的超声波作用。

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Corresponding author:Prof. ZHANG Aiping，dongdian510@163.com

Foundation item:supported by the National Natural Science Foundation of China(51476025).

Simulation study on influential of ultrasonic cavitation on fouling deposition characteristic

ZHANG Aiping，FENG Zhuo，DING Quan，XU Zhiming

(CollegeofEnergyandPowerEngineeringNortheastElectricPowerUniversityJilin132012，Jilin,China)

Abstract：In the process of ultrasonic antiscaling，the spread of ultrasonic and cavitation effect will be affected by the fluid and ultrasonic parameters，deposition character of crystallization fouling will also be changed. Thus，using the method of the FLUENT software numerical simulation compared with the experimental parameters，the effect of ultrasonic cavitation on CaSO4crystallization fouling removal is studied in the different fluid velocity and the ultrasonic frequencies. Results show that under the conditions of the same frequency，increasing velocity of fluid，the removal effect of ultrasonic cavitation on fouling is weakened. The removal rate caused by cavitation effect was brought into the fouling deposition process，and the effect of ultrasonic frequencies on the fouling character was obtained. With the increase of ultrasonic frequencies，fouling net deposition rate and fouling resistance increased.

Key words：ultrasonic cavitation；crystallization fouling；deposition character；numerical simulation

DOI：10.11949/j.issn.0438-1157.20170615

2017-05-15收到初稿，2017-06-05收到修改稿。