Working principle of vortex flowmeter

NegotiableUpdate on 03/21

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Nature of the Manufacturer: Producers

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Place of Origin

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Overview

Setting up a vortex generator (blocking fluid) in the fluid and alternately generating regular vortices from both sides of the vortex generator is called a Karman vortex street, as shown in Figure 1. The vortices are arranged asymmetrically downstream of the vortex generator. Assuming the frequency of vortex occurrence is f, the average velocity of the measured medium flow is U, the width of the vortex generator face is d, and the diameter of the body is D. According to the principle of Karman vortex street, there is the following relationship: where: the average flow velocity on both sides of the vortex generator, m/s Strouhal number, the ratio of the arch area on both sides of the vortex generator to the cross-sectional area of the pipeline; the instantaneous volume flow rate of the Karman vortex street is: the instrument coefficient of the K meter, the pulse number/m3 (P/m3) K is not only related to the geometric dimensions of the vortex generator and pipeline, but also to the Strouhal number. The Strouhal number is a dimensionless parameter that is related to the shape of the vortex generator and the Reynolds number. Figure 2 shows the relationship between the Strouhal number of a cylindrical vortex generator and the Reynolds number of a pipeline. As can be seen from the figure, in the range of Re=2104~7106, St can be regarded as a constant. This is the curve of the relationship between Strouhal number and Reynolds number in the normal working range of the instrument

Product Details

In the formula:
- Average flow velocity on both sides of the vortex generator, m/s
Strouhal number
The ratio of the bow shaped area on both sides of the vortex generator to the cross-sectional area of the pipeline


Kaman Vortex Street

winkTime volume flow rateFor:
The instrument coefficient of the K-meter in the formula, pulse count/m3 (P/m3)
	K is not only related to the geometric dimensions of the vortex generator and pipeline, but also to the Strouhal number. The Strouhal number is a dimensionless parameter that is related to the shape of the vortex generator and the Reynolds number. Figure 2 shows the relationship between the Strouhal number of a cylindrical vortex generator and the Reynolds number of a pipeline
As shown in the figure, within the range of Re=2 × 104~7 × 106, St can be regarded as a constant, which is the normal operating range of the instrument

The relationship curve between Strouhal number and Reynolds number

1. Small pressure loss, large range, and high accuracy;

When measuring the volumetric flow rate under working conditions, it is almost unaffected by parameters such as fluid density, pressure, temperature, viscosity, etc;

3. No movable mechanical parts, therefore high reliability and low maintenance;

4. The instrument parameters can remain stable for a long time. This instrument adopts a piezoelectric stress sensor with high reliability and can operate within a temperature range of -25 ℃ to+320 ℃;

5. It has a wide range of applications and can measure the flow rates of fluids such as steam, gas, and liquid;

6. Humanized menu and interface based on dot matrix display, with bright backlight, supporting both Chinese and English languages, suitable for various customer groups;

7. Support temperature and pressure measurement, convenient for gas medium temperature and pressure compensation needs;

8. Support flow rate conversion display function, convenient for on-site viewing of current flow rate;

9. Support split screen display function, which can enlarge and display single or two parameters (temperature, pressure, operating conditions, flow rate and flow rate under standard conditions, etc.) on the screen;

10. Simulation output function, supporting 4-20mA current simulation and frequency output simulation, convenient for on-site non real current debugging;

11. Supports 4-20mA output, pulse (equivalent) output, alarm output, RS485 communication output;

Both two-wire and three wire systems have DCDC (DC1000V) isolation;

1. Main technical parameters

Measurement medium	Gas, liquid, steam
Execution standards	Vortex flow sensor (JB/T 9249-1999)
Verification regulations	Vortex flowmeter (JJG 1029-2007)
Connection method	Card mounted, flange mounted
Nominal diameter	DN25、DN32、DN40、DN50、DN65、DN80、DN100、DN125、DN150、DN200、DN250、DN300
Flange standard	Conventional standards	GB/T9113-2000
	Other standards	International pipe flange standard	Such as German standard DIN, American standard ANSI, Japanese standard JIS
		Domestic pipe flange standards	Such as the standards of the Ministry of Chemical Industry and the Ministry of Machinery
Verification conditions	verification device	Sonic nozzle flow verification device
accuracy class	Level 1.5
Range ratio	1:10
flow rate range	Liquid: 0.5-7m/s Gas: 5-50m/s
Instrument material	304 stainless steel, 316 stainless steel
temperature range	-25 ℃ to 100 ℃- 25 ℃~+280 ℃- 25℃～+320℃
pressure rating	1.6MPa, 2.5MPa, 4.0MPa
output signal	pulse frequency signal
	Two wire 4-20mA DC current signal
	485 communication
power supply	24V DC
Explosion proof grade	Basic Type: Non Explosion proof Product, Explosion proof Type: Exd Ⅱ BT4
protection grade	IP65
environmental condition	Environmental temperature: -25 ℃~55 ℃ Relative humidity: 5~90% Atmospheric pressure: 86~106KPa

2. Flow range of liquid and working gas

Diameter DN (mm)	Liquid (m3/h)	Gas (m3/h)	Diameter DN (mm)	Liquid (m3/h)	Gas (m3/h)
25	1~12	8~80	100	20~200	140~1400
32	1.5～23	15~150	125	31~310	220~2200
40	2.4～32	23~230	150	45~450	300~3000
50	6.3～84	35~350	200	80~800	550~5500
65	10~130	60~600	250	150~1500	880~8800
80	10~130	90~900	300	200~2000	1300~13000

3. Density of commonly used gas media under standard conditions (0.1013mbar, 20 ℃)

gas	Density (Kg/m3)	gas	Density (Kg/m3)	gas	Density (Kg/m3)
acetylene	1.083	Butane	2.1463	ethane	1.2500
ammonia	0.7080	ethylene	1.1660	methane	0.6669
propane	1.8332	neon	0.83914	Natural gas	0.776
air	1.2041	argon	1.6605	carbon dioxide	1.829
carbon monoxide	1.165	hydrogen	0.0838	oxygen	1.3302
propylene	1.7459	nitrogen	1.1646

4. Saturated vapor density table

Gauge pressure (MPa)	Temperature (℃)	Density (kg/m3)	Gauge pressure (MPa)	Temperature (℃)	Density (kg/m3)
0.1	120.23	1.129	1.0	184.15	5.641
0.2	133.54	1.651	1.1	187.96	6.127
0.3	143.62	2.163	1.3	195.04	7.106
0.4	151.84	2.669	1.5	201.37	8.085
0.5	158.94	3.170	1.7	207.11	9.065
0.6	164.96	3.667	1.9	212.37	10.05
0.7	170.41	4.162	2.1	217.32	11.032
0.8	175.36	4.655	2.3	221.86	12.019
0.9	179.88	5.147	2.5	226.11	13.011

5. Superheated steam density table

cut offPressure P (MPa）	Temperature t (℃)
cut offPressure P (MPa）	100	110	120	130	140	150	160	170	180
0.1	0.590	0.573	0.558	0.543	0.529	0.516	0.504	0.492	0.481
0.2	——	——	1.137	1.099	1.070	1.042	1.016	0.992	0.969
0.3	——	——	——	1.674	1.622	1.578	1.537	1.499	1.463
0.4	——	——	——	——	2.197	2.125	2.067	2.014	1.964
0.5	——	——	——	——	——	2.666	2.608	2.528	2.472
0.6	——	——	——	——	——	——	3.159	3.071	2.989
0.7	——	——	——	——	——	——	——	3.614	3.514
0.8	——	——	——	——	——	——	——	4.168	4.048
0.9	——	——	——	——	——	——	——	——	4.591
1.0	——	——	——	——	——	——	——	——	5.145
1.1	——	——	——	——	——	——	——	——	——
1.2	——	——	——	——	——	——	——	——	——
1.3	——	——	——	——	——	——	——	——	——
1.4	——	——	——	——	——	——	——	——	——
1.5	——	——	——	——	——	——	——	——	——
1.6	——	——	——	——	——	——	——	——	——
1.7	——	——	——	——	——	——	——	——	——
1.8	——	——	——	——	——	——	——	——	——
1.9	——	——	——	——	——	——	——	——	——
2.0	——	——	——	——	——	——	——	——	——
2.1	——	——	——	——	——	——	——	——	——
2.2	——	——	——	——	——	——	——	——	——
2.3	——	——	——	——	——	——	——	——	——
2.4	——	——	——	——	——	——	——	——	——
2.5	——	——	——	——	——	——	——	——	——
2.6	——	——	——	——	——	——	——	——	——
2.7	——	——	——	——	——	——	——	——	——
2.8	——	——	——	——	——	——	——	——	——
2.9	——	——	——	——	——	——	——	——	——
3.0	——	——	——	——	——	——	——	——	——
3.1	——	——	——	——	——	——	——	——	——
3.2	——	——	——	——	——	——	——	——	——
3.3	——	——	——	——	——	——	——	——	——
3.4	——	——	——	——	——	——	——	——	——
3.5	——	——	——	——	——	——	——	——	——
3.6	——	——	——	——	——	——	——	——	——
3.7	——	——	——	——	——	——	——	——	——
3.8	——	——	——	——	——	——	——	——	——
3.9	——	——	——	——	——	——	——	——	——
4.0	——	——	——	——	——	——	——	——	——

Absolute pressure P (MPa)）	Temperature t (℃)
Absolute pressure P (MPa)）	190	200	210	220	230	240	250	260	270
0.1	0.471	0.460	0.451	0.441	0.432	0.424	0.416	0.408	0.400
0.2	0.947	0.926	0.906	0.887	0.868	0.851	0.834	0.818	0.803
0.3	1.428	1.396	1.365	1.336	1.308	1.281	1.256	1.231	1.208
0.4	1.916	1.872	1.829	1.789	1.751	1.715	1.680	1.647	1.615
0.5	2.411	2.353	2.299	2.247	2.198	2.152	2.108	2.066	2.052
0.6	2.912	2.841	2.773	2.710	2.650	2.593	2.539	2.487	2.438
0.7	3.421	3.334	3.253	3.178	3.106	3.038	2.973	2.911	2.853
0.8	3.937	3.834	3.738	3.650	3.565	3.486	3.411	3.389	3.271
0.9	4.461	4.342	4.230	4.127	4.029	3.939	3.852	3.769	3.691
1.0	4.995	4.857	4.728	4.610	4.498	4.394	4.297	4.023	4.115
1.1	5.538	5.379	5.233	5.088	4.973	4.855	4.745	4.641	4.542
1.2	6.089	5.909	5.745	5.593	5.452	5.321	5.197	5.082	4.972
1.3	6.614	6.448	6.263	6.093	5.936	5.790	5.654	5.526	5.402
1.4	——	6.996	6.789	6.600	6.426	6.265	6.115	5.974	5.841
1.5	——	7.554	7.324	7.114	6.922	6.744	6.579	6.425	6.280
1.6	——	——	7.866	7.635	7.423	7.229	7.049	6.880	6.723
1.7	——	——	8.418	8.163	7.931	7.719	7.522	7.340	7.169
1.8	——	——	8.978	8.699	8.446	8.214	8.001	7.803	7.619
1.9	——	——	9.549	9.234	8.967	8.715	8.484	8.271	8.072
2.0	——	——	——	9.795	9.485	9.222	8.973	8.743	8.529
2.1	——	——	——	10.356	10.030	9.735	9.466	9.219	8.990
2.2	——	——	——	10.927	10.573	10.255	9.965	9.700	9.455
2.3	——	——	——	11.507	11.124	10.781	10.470	10.186	9.924
2.4	——	——	——	——	11.683	11.313	10.980	10.676	10.397
2.5	——	——	——	——	12.250	11.853	11.496	11.172	10.875
2.6	——	——	——	——	12.827	12.401	12.019	11.673	11.356
2.7	——	——	——	——	13.414	12.957	12.547	12.179	11.843
2.8	——	——	——	——	——	13.519	13.082	12.690	12.334
2.9	——	——	——	——	——	14.090	13.624	13.208	12.830
3.0	——	——	——	——	——	14.671	14.174	13.731	13.331
3.1	——	——	——	——	——	15.260	14.731	14.260	13.837
3.2	——	——	——	——	——	15.859	15.295	14.796	14.348
3.3	——	——	——	——	——	16.468	15.868	15.338	14.864
3.4	——	——	——	——	——	——	16.448	15.887	15.387
3.5	——	——	——	——	——	——	17.037	16.442	15.914
3.6	——	——	——	——	——	——	17.636	17.007	16.447
3.7	——	——	——	——	——	——	18.245	17.578	16.990
3.8	——	——	——	——	——	——	18.861	18.155	17.535
3.9	——	——	——	——	——	——	19.489	18.741	18.087
4.0	——	——	——	——	——	——	——	19.335	18.646

Absolute pressure P (MPa)	Temperature t (℃)
Absolute pressure P (MPa)	280	290	300	310	320	330	340	350
0.1	0.393	0.386	0.379	0.372	0.366	0.360	0.354	0.348
0.2	0.788	0.774	0.760	0.747	0.734	0.721	0.709	0.698
0.3	1.185	1.163	1.142	1.122	1.103	1.084	1.066	1.049
0.4	1.585	1.555	1.527	1.500	1.474	1.449	1.424	1.400
0.5	1.986	1.949	1.914	1.879	1.846	1.815	1.784	1.754
0.6	2.391	2.345	2.302	2.260	2.220	2.182	2.145	2.109
0.7	2.797	2.743	2.693	2.643	2.596	2.551	2.507	2.465
0.8	3.206	3.145	3.085	3.028	2.974	2.921	2.871	2.822
0.9	3.608	3.547	3.479	3.405	3.352	3.293	3.236	3.181
1.0	4.032	3.952	3.876	3.804	3.734	3.667	3.602	3.541
1.1	4.448	4.359	4.275	4.195	4.117	4.042	3.971	3.902
1.2	4.869	4.771	4.675	4.587	4.500	4.419	4.304	4.264
1.3	5.291	5.181	5.079	4.980	4.888	4.789	4.710	4.630
1.4	5.718	5.596	5.485	5.376	5.274	5.179	5.084	4.995
1.5	6.143	6.013	5.893	5.777	5.666	5.559	5.459	5.362
1.6	6.575	6.435	6.301	6.177	6.057	5.942	5.834	5.730
1.7	7.008	6.859	6.716	6.579	6.541	6.329	6.211	6.099
1.8	7.446	7.283	7.133	6.983	6.849	6.716	6.592	6.470
1.9	7.886	7.710	7.547	7.391	7.246	7.102	6.969	6.843
2.0	8.333	8.143	7.968	7.800	7.645	7.496	7.353	7.217
2.1	8.777	8.578	8.391	8.214	8.047	7.888	7.737	7.593
2.2	9.227	9.015	8.816	8.628	8.451	8.283	8.123	7.970
2.3	9.681	9.455	9.244	9.045	8.679	8.510	8.349	8.349
2.4	10.139	9.899	9.675	9.464	9.265	9.078	8.899	8.729
2.5	10.061	10.347	10.108	9.886	9.676	9.478	9.290	9.112
2.6	11.066	10.797	10.545	10.310	10.089	9.880	9.680	9.495
2.7	11.534	11.250	10.984	10.737	10.504	10.285	10.078	9.880
2.8	12.008	11.706	11.427	11.167	10.922	10.962	10.473	10.267
2.9	12.484	12.167	11.872	11.598	11.342	11.100	10.872	10.656
3.0	12.967	12.630	12.321	12.034	11.765	11.511	11.273	11.047
3.1	13.542	13.099	12.773	12.470	12.189	11.925	11.674	11.439
3.2	13.941	13.570	13.229	12.912	12.617	12.340	12.079	11.833
3.3	14.436	14.047	13.687	13.355	13.046	12.757	12.484	12.228
3.4	14.937	14.526	14.148	13.801	13.479	13.177	12.893	12.626
3.5	15.439	15.008	14.616	14.251	13.914	13.598	13.303	13.025
3.6	15.949	15.497	15.073	14.704	14.351	14.023	13.716	13.426
3.7	16.464	15.990	15.557	15.158	14.791	14.449	14.130	13.829
3.8	19.984	16.485	16.033	15.618	15.235	14.879	14.546	14.235
3.9	17.507	16.997	16.513	16.080	15.681	15.312	14.966	14.641
4.0	18.038	17.492	16.998	16.545	16.129	15.746	15.387	15.049