锥形气体层流元件结构设计及流动特性研究

doi:10.11949/0438-1157.20241377

摘要/Abstract

摘要：

为解决常规层流流量计（laminar flow meter，LFM）线性度不佳的问题，设计了一款内有导锥、环形截面的层流元件，并且通过将引压孔设置在层流段的方式进一步提高了压差-流量线性度。采用计算流体力学（computational fluid dynamics，CFD）仿真技术确定了合理的导锥角度为30°，对流道尺寸分析发现，流道大小对测量段压差影响较大，流量误差随流道的增大而减小。以空气、N₂、CO₂气体为工质，探究了层流元件对不同气体的适用性，三者的流量误差均小于2%。借助CFD仿真技术对新型层流流量计进行模拟计算能够得到流道沿程压力损失和内部流场的详细数据，可以为实验提供有用的流动细节、可行的设计思路，从而提高实验效率。

关键词: 层流, 锥形层流元件, 优化设计, 计算流体力学, 流动特性

Abstract:

A laminar flow element with a guide cone and annular cross-section was designed to solve the problem of poor linearity in traditional laminar flow meters (LFM), and pressure-measurement position was directly put in the laminar flow section for further improving the linearity between pressure difference and flow rate. Using computational fluid dynamics (CFD) simulation technology to determine a reasonable guide cone angle is 30°. Analysis of the channel size reveals that it has a significant impact on the pressure difference in the measurement section, and the flow error decreases with the increase of the channel size. The applicability of laminar flow elements to different gases was explored using air, N₂ and CO₂ as working fluids, and the flow errors of the three were all less than 2%. By using CFD simulation technology to simulate the new laminar flow meter, detailed data on pressure loss along the flow channel and internal flow field can be obtained, which can provide useful flow details, feasible design ideas, and improve experimental efficiency.

Key words: laminar, cone laminar flow element, optimal design, CFD, flow characteristic

中图分类号:

TH 814

曹潇风, 张华海, 王江云, 王利民. 锥形气体层流元件结构设计及流动特性研究[J]. 化工学报, 2025, 76(9): 4440-4448.

Xiaofeng CAO, Huahai ZHANG, Jiangyun WANG, Limin WANG. Structural design and flow characteristics of conical gas laminar flow element[J]. CIESC Journal, 2025, 76(9): 4440-4448.

图/表 19

图1 常规层流流量计结构及压力损失

Fig.1 Structure and pressure loss of conventional laminar flow meter

图2 层流流量计的几何信息

Fig.2 Geometric information of laminar flow meter

表1 层流流量计参数设计

Table 1 Parameter design of laminar flow meter

r₁/mm	r₂/mm	L/mm	L_e/mm
8.0	7.7	180.0	20.0
8.0	7.8	180.0	15.0
8.0	7.9	180.0	10.0

图3 锥形层流元件计算网格

Fig.3 Calculation grid of conical laminar flow element

图4 不同网格数量下流速沿轴向的分布

Fig.4 Velocity distribution along the axial direction with different grid numbers

图5 流量-压差关系图

Fig.5 Flow rate-pressure difference relationship diagram

表2 不同计算配置的加速情况

Table 2 Acceleration ratio of different computing configurations

配置	计算时间/s	加速比
16 CPU	5.040	—
1 GPU	0.400	12.60
2 GPU	0.275	18.32
3 GPU	0.250	20.00
4 GPU	0.250	20.00
5 GPU	0.255	19.76
6 GPU	0.290	17.38

图6 流量-压差的线性度

Fig.6 Linearity of flow rate and pressure differenc

图7 不同流量下的线性度

Fig.7 Linearity of different flow rate

图8 流道内速度轴向分布

Fig.8 Axial velocity distribution in the flow channel

图9 速度云图

Fig.9 Cloud map of velocity

表3 环隙流道尺寸为0.1 mm时的模拟数据

Table 3 Simulated data of annular gap type laminar flow meter（0.1 mm）

ΔP/Pa	q_r/(L/min)	q_t/(L/min)	δ/%
0	0	0	0
854.10	0.2	0.20	0.50
2987.80	0.7	0.70	0.55
42354.14	10	9.87	1.31
84711.21	20	19.74	1.31
127050.22	30	29.60	1.32
169448.27	40	39.48	1.30
211814.38	50	49.35	1.29
232998.74	55	54.29	1.29

表4 环隙流道尺寸为0.2 mm时的模拟数据

Table 4 Simulated data of annular gap type laminar flow meter （0.2 mm）

ΔP/Pa	q_r/(L/min)	q_t/(L/min)	δ/%
0	0	0	0
1073.81	2	1.98	1.21
3759.14	7	6.92	1.19
6444.14	12	11.86	1.19
9129.31	17	16.80	1.19
10740.02	20	19.76	1.20
16107.14	30	29.64	1.21
21476.71	40	39.52	1.21
30351.07	56.5	55.85	1.16

表5 环隙流道尺寸为0.3 mm时的模拟数据

Table 5 Simulated data of annular gap type laminar flow meter （0.3 mm）

ΔP/Pa	q_r/(L/min)	q_t/(L/min)	δ/%
0	0	0	0
160.13	1	0.99	0.74
800.65	5	4.96	0.74
1601.14	10	9.92	0.75
2722.14	17	16.87	0.74
3202.414	20	19.85	0.74
4803.04	30	29.77	0.75
6406.47	40	39.71	0.72
8018.38	50	49.71	0.60
8825.47	55	54.68	0.59

图10 流量-压差关系图

Fig.10 Relationship of flow rate and pressure difference

表6 氮气的模拟数据

Table 6 Simulated data of nitrogen

ΔP/Pa	q_r/(L/min)	q_t/(L/min)	δ/%
29.76	0.2	0.196	1.896
148.82	1	0.981	1.873
446.48	3	2.944	1.866
1041.63	7	6.868	1.881
1487.98	10	9.811	1.886
2976.20	20	19.624	1.878
4463.78	30	29.433	1.889
5953.93	40	39.259	1.853
8203.17	55	54.090	1.655

表7 二氧化碳的模拟数据

Table 7 Simulated data of carbon dioxide

ΔP/Pa	q_r/(L/min)	q_t/(L/min)	δ/%
24.51	0.2	0.196	1.895
85.75	0.7	0.686	1.946
245.14	2	1.9621	1.896
612.98	5	4.906	1.875
1225.84	10	9.812	1.884
2084.36	17	16.683	1.864
2452.63	20	19.631	1.846
2945.01	24	23.572	1.784
3687.42	30	29.514	1.620

图11 空气、氮气和二氧化碳的流量-压差关系

Fig.11 Relationship of flow rate and pressure difference (Air、N2、CO2)

图12 空气、氮气和二氧化碳流量的相对误差

Fig.12 Relative error of flow rate (Air、N2、CO2)

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