Study and prediction of flow field in the annular region of geometrically similar turbo air classifier

doi:10.11949/0438-1157.20230301

Abstract

Abstract:

In order to explore the distribution characteristics of the flow field in the annular region of the geometrically similar turbo air classifier, the turbo air classifier models of different sizes were established, the geometric parameters of the key structures were extracted, and the influence of the size scale factor on the flow field distribution in the annular region of the classifier was analyzed through numerical simulation. The numerical simulation results show that under the same air inlet velocity, the tangential velocity distribution in the annular region of the geometrically similar classifier model presents the distribution of quasi-free vortices. With the increase of model size, the area weighted average tangential velocity of cylinder surface in the annular region increases, and the overall distribution of tangential velocity in the annular region is non-uniform. If the tangential velocities are similar between the inner and outer edges of the rotor cage, the tangential velocity fluctuation is small in the annular region. The radial velocity distribution in the annular region of the geometrically similar classifier model conforms to the law of point sink. Except for the large difference in the radial velocity values near the outer edge of the rotor cage, the area weighted average radial velocity of the cylinder surface in the annular region does not change with the scale factor of the classifier. The numerical simulation data of geometrically similar classifier models are used as the training samples to fit the prediction formula of the area weighted average tangential velocity and radial velocity of the cylinder surface in the annular region of the classifier, and the test and verify sample classifier model is established to test the prediction formulas. The maximum errors between the predicted and simulated area weighted average tangential velocity and radial velocity of the cylinder surface are 3.5% and 1.8%, respectively. In addition, by analyzing the kinematic similarity and dynamic similarity of the flow field in the annular region of the geometrically similar turbo air classifier models, it is concluded that the flow fields of geometrically similar classifier models have similarity.

Key words: turbo air classifier, geometric similarity, numerical simulation, flow field velocity, prediction, fluid mechanics

摘要：

为探究几何相似涡流空气分级机环形区流场的分布特性，建立不同尺寸的涡流空气分级机模型，提取关键结构的几何参数，通过数值模拟分析尺寸比例因数对分级机环形区流场分布的影响。模拟结果表明，在相同进口风速下，几何相似分级机模型环形区内切向速度呈准自由涡的分布。模型尺寸增大，环形区内柱面面积加权平均切向速度增大，环形区切向速度分布不均匀。转笼内外缘切向速度越接近，环形区内近转笼外缘处切向速度产生的波动越小。几何相似分级机模型环形区内径向速度分布符合点汇流动的规律，除了在靠近转笼外缘处径向速度数值有较大差异外，环形区其余位置柱面面积加权平均径向速度不随比例因数变化而变化。以几何相似分级机模型数值模拟数据作为训练样本拟合分级机环形区内柱面面积加权平均切向速度和径向速度预测公式，并建立测试样本分级机模型对预测公式进行验证。柱面面积加权平均切向速度和径向速度预测值与模拟值的最大误差分别为3.5%和1.8%。此外，通过对几何相似涡流空气分级机模型环形区流场运动相似和动力相似分析，得出几何相似分级机模型流场具有相似性。

关键词: 涡流空气分级机, 几何相似, 数值模拟, 流场速度, 预测, 流体力学

CLC Number:

TQ 051.8

Yuan YU, Weiwei CHEN, Junjie FU, Jiaxiang LIU, Zhiwei JIAO. Study and prediction of flow field in the annular region of geometrically similar turbo air classifier[J]. CIESC Journal, 2023, 74(6): 2363-2373.

于源, 陈薇薇, 付俊杰, 刘家祥, 焦志伟. 几何相似涡流空气分级机环形区流场变化规律研究及预测[J]. 化工学报, 2023, 74(6): 2363-2373.

Figures/Tables 11

Fig.1 Structure diagram of a turbo air classifier

Table 1 Main structural dimensions of geometrically similar turbo air classifier models

尺寸比例因数k₁	D_v	D_zn	D_zw	D_dn	b	a
1	219	70	100	132	48	31
2	438	140	200	264	96	62
4	876	280	400	528	192	124
8	1752	560	800	1056	384	248

Fig.2 The tangential velocity contours in the annular region of the geometrically similar turbo air classifier models

Fig.3 Area weighted average tangential velocity curves of the cylinder surface in the annular region of geometrically similar turbo air classifier models

Fig.4 The radial velocity contours in the annular region of geometrically similar turbo air classifier models

Fig.5 Area weighted average radial velocity curves of the cylinder surface in the annular region of geometrically similar turbo air classifier models

Table 2 Area weighted average tangential velocity of the cylinder surface in the annular region of classifier models

(D/2k₁)/mm	平均切向速度/(m/s)
(D/2k₁)/mm	k₁=1	k₁=2	k₁=4	k₁=8
51	21.70	22.89	23.33	25.09
52	21.40	22.57	23.02	24.57
53	20.97	22.19	22.70	24.32
54	20.57	21.78	22.36	23.82
55	20.45	21.38	21.97	23.34
56	20.05	20.97	21.55	23.00
57	19.61	20.57	21.14	22.44
58	19.29	20.19	20.74	22.03
59	19.01	19.87	20.31	21.46
60	18.61	19.53	19.87	20.93
61	18.22	19.19	19.46	20.41
62	18.00	18.68	18.98	19.78
63	17.60	18.27	18.49	19.06
64	17.28	18.00	18.08	18.70

Table 3 Coefficients C1 and C2 of the prediction formula for area weighted average tangential velocity of the cylinder surface in annular region of classifier models

模型	尺寸比例因数k₁	C₁	C₂
D_zw=100 mm	1	1165	-1.010
D_zw=200 mm	2	1480	-1.059
D_zw=400 mm	4	2151	-1.145
D_zw=800 mm	8	3793	-1.272

Fig.6 Predicted and simulated area weighted average tangential velocity of the cylinder surface in the annular region of geometrically similar classifier models

Fig.7 Predicted and simulated area weighted average radial velocity of the cylinder surface in the annular region of geometrically similar classifier models

Fig.8 The curves of the variation of RevsEu

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