CN208860411U - A kind of concave arc shape double fluid is to mean velocity tube flowmeter - Google Patents

Abstract

The utility model relates to a kind of concave arc shape double fluids to mean velocity tube flowmeter, including the detection bar being diametrically inserted into measurement pipeline, the stagnation pressure tube and static tube that are arranged in detection bar, stagnation pressure tube is located at fluoran stream surface, static tube is located at lee side, the fluoran stream surface and lee side of detection bar are provided with pitot hole and static pressure hole, all pitot holes are connected with stagnation pressure tube, draw average total pressure p from stagnation pressure tube；All static pressure holes are communicated with static tube, draw static pressure p from static tube；The difference of the stagnation pressure p and static pressure p measured is utilized to obtain the size of mean flow rate on pipeline section, which is characterized in that for the cross sectional shape of detection bar similar to diamond shape, four sides are concave arc shape, and fluoran stream surface and lee side are convex, and the side of the concave arc shape place that connects is streamlined.The utility model can effectively improve the output differential pressure of mean velocity tube flowmeter, promote the precision of even speed tube low discharge measurement.

Description

A kind of concave arc shape double fluid is to mean velocity tube flowmeter

Technical field

The utility model relates to mean velocity tube flowmeters.

Background technique

Mean velocity tube flowmeter as one of plug-in type flow instrument (foreign countries claim Annubar, Verabar, Probar etc.) It is a kind of differential pressure flowmeter to be grown up based on Pitot tube measuring principle in the later period sixties.With traditional flow sensors ratio, Mean velocity tube flowmeter because the advantage that its structure is simple, easy for assemble or unload, the pressure loss is small, at low cost be widely used in electric power, In the flow measurement of the industries large diameter pipeline such as metallurgy, petrochemical industry.It has many advantages, such as following:

(1) have a wide range of application.Mean velocity tube flowmeter can be used for the flow measurement of all fluids without solid particle；It is applicable in Pipe diameter wider range, minimum diameter is up to 25mm, and maximum gauge is up to 9m；It is (such as rectangular that irregular pipeline can be measured Or rectangular duct) flow.

(2) mean velocity tube flowmeter structure is simple, light-weight, and installation dismantles, is easy to maintenance, it can be achieved that the dismounting that do not stop, system It makes at low cost.

(3) pressure loss is small, energy saving.The irrecoverable pressure loss of mean velocity tube flowmeter only account for its export differential pressure 2~ Hereinafter, considerably reducing power consumption, energy-saving effect is significant for 15%, only the 5% of orifice plate.

(4) accuracy long-time stability are good.Mean velocity tube flowmeter is without movable and easy-abrasion part, when caliber is greater than When 300mm, accuracy can reach ± 1%, and stability is ± 0.1%, the practical requirement of general satisfaction.

Mean velocity tube flowmeter is plug-in type differential pressure flow transducer, and detection bar cross section circumscribed circle diameter is much smaller than pipeline Cross-sectional diameter causes it to export differential pressure smaller, and generates fluctuation vulnerable to the influence of detection bar downstream vortex, makes average rate pipeline Property degree, repeatability are difficult to improve.Therefore since mean velocity tube flowmeter comes out, scientific research personnel has been devoted to its cross sectional shape Research improves the performance indicators such as its linearity, repeatability to increase mean velocity tube flowmeter output differential pressure.Currently, most widely used Have 4 kinds of even speed tube cross sectional shapes: circle, diamond shape, Delta shape and bullet-headed.

(a) round: earliest even speed tube detection bar cross sectional shape found fluid in reynolds number Re < 10 later⁵When, it is cut in circle Burble point is 78 ° on face；And Re > 10⁶When, burble point will turn into 130 °, when Re is in 10⁵~10⁶Between when, burble point is not true It is fixed, thus draw the deviation that discharge coefficient has nearly ± 10%.

(b) diamond shape: being released for 1978 by DSI company, the U.S., and there are sharp edge, fluids to flow around them for detection bar cross section When, burble point is fixed on sharp edge.Mainly solve point of flow separation variation issue existing for round mean velocity tube flowmeter, it can To obtain higher differential pressure, but its repeatability is less desirable.

(c) Delta shape is released by German Cisco System Co., and performance is not much different with diamond shape even speed tube, what burble point was fixed Meanwhile even speed tube stream field itself also produces larger impact, there is exercise intensity in region downstream and scale is all biggish Whirlpool is affected by it, and even speed tube differential pressure fluctuation is larger, and repeatability is affected, and the linearity is also difficult to increase again.

(d) bullet-headed, it is released by Veris company, the U.S. within 1992, referred to as Verbar.Verbar is in its bullet front-end table Coarse processing has been done in face, improves its accuracy of measurement.It is bullet-shaped to use fairshaped cross sectional shape, reduce even speed tube stream field Influence, the linearity increases.The position of static pressure point but makes its output differential pressure relatively low with respect to other types even speed tube many, shadow Its measurement effect in low-density, low flow velocity is rung.

Utility model content

The purpose of this utility model is provided a kind of new according to the rule that interacts between even speed tube cross sectional shape and flow field Type cross sectional shape even speed tube is named as concave arc shape double fluid to mean velocity tube flowmeter.The utility model can effectively improve even speed tube The output differential pressure of flowmeter promotes the precision of even speed tube low discharge measurement, to expand the application range of differential pressure flowmeter.This Utility model takes following technical scheme:

A kind of concave arc shape double fluid exists including the detection bar be diametrically inserted into measurement pipeline, setting to mean velocity tube flowmeter Stagnation pressure tube and static tube in detection bar, stagnation pressure tube are located at fluoran stream surface, and static tube is located at lee side, detection bar fluoran stream surface and Lee side is provided with pitot hole and static pressure hole, and all pitot holes are connected with stagnation pressure tube, draws average total pressure p from stagnation pressure tube； All static pressure holes are communicated with static tube, draw static pressure p from static tube；Reflect pipeline using the difference of the stagnation pressure p and static pressure p measured The size of mean flow rate on section, which is characterized in that the cross sectional shape of detection bar is concave arc shape similar to diamond shape, four sides, meets stream Face and lee side are convex, and the side of the concave arc shape place that connects is streamlined.

Preferably, in the case where meeting processing technology requirement, the curvature on each concave arc shape side is the bigger the better.According to right It is required that flowmeter described in 1, which is characterized in that the concave arc radius (R1) and detection bar circumscribed circle diameter (L1) on each concave arc shape side Ratio control 0.25~3.The described flowmeter bilateral symmetry, stagnation pressure tube and static tube can exchange, with realize double fluid to Flow measurement.

The utility model has the advantage that compared with prior art due to taking above technical scheme

(1) it is mutually tied according to Fluid Mechanics Computation emulation and even speed tube working principle, the analysis of pressure port ways of measure pressure scheduling theory The method of conjunction, the influence from flow field development mechanism angle research detection bar cross sectional shape to even speed tube stagnation pressure, static pressure, to realize Structure optimization of the concave arc shape double fluid to mean velocity tube flowmeter cross sectional shape.Within the scope of biggish measuring water flow, concave arc shape Double fluid can export larger and stable differential pressure to mean velocity tube flowmeter, 2~3 times high than tradition even speed tube structure, and flow Measurement reproducibility, the linearity are preferable, can reach ± (1~2) %, therefore significantly improve the precision of flow measurement.

(2) for concave arc shape double fluid to mean velocity tube flowmeter symmetrical configuration, pitot hole is consistent with static pressure hole ways of measure pressure, and only needs It arranges in pairs or groups a differential pressure transmitter, so that it may realize that the double fluid of fluid to measurement, can reduce the measurement cost of mean velocity tube flowmeter.

(3) for concave arc shape double fluid to mean velocity tube flowmeter without movable member, general profile, symmetrical junction is can be used in whole components Structure design, installation, maintenance is convenient, it can be achieved that the dismounting that do not stop, economic cost generally is lower, and will not generate any form Waste of material.

(4) due to the simplicity of structure and the standard universal of all components, concave arc shape double fluid is to mean velocity tube flowmeter Structural parameters can carry out analytical calculation by existing business finite element analysis software, so as to facilitate engineers and technicians' root According to different actual requirement of engineering, flexible choice Different structural parameters value optimizes the device.

Detailed description of the invention

Fig. 1 is current widely used 4 kinds of even speed tubes cross sectional shape figure.

Fig. 2 (a) and be (b) that the concave arc shape double fluid of the utility model shows to mean velocity tube flowmeter structure with cross sectional shape respectively It is intended to.

Figure label explanation: 1 measurement pipeline；2 detection bars；3 stagnation pressure tubes；4 static tubes；

5 pitot holes；6 static pressure holes；D detects pole length；L1 detection bar circumscribed circle diameter；

R1 concave arc radius；R2 convex arc radius；L2 convex arc width；T berm width；

Δ L pressure port away from.

It is wherein customized: to indicate that the segment structure is straight flange when R1=0.

Fig. 3 is the concave arc shape double fluid of the utility model to mean velocity tube flowmeter pressure port position view.

Figure label explanation: r₁The first pair of distance of pressure port center away from pipeline center；r₂Second pair of pressure port center is away from pipe The distance at road center；R measures pipeline inside radius.

Fig. 4 is the velocity simulation cloud atlas that detection bar influences measurement pipeline interior flow field.

Fig. 5-Fig. 7 is the simulation result comparison diagram that different detection bar cross sectional shapes generate differential pressure signal.

Fig. 8 is emulation data and actual measurement number of the concave arc shape double fluid of the utility model to mean velocity tube flowmeter at DN200 According to comparison diagram.

Fig. 9 is the concave arc shape double fluid of the utility model to mean velocity tube flowmeter and diamond shape mean velocity tube flowmeter static test mark Determine comparative result figure.

Specific embodiment

The utility model is described in detail with reference to the accompanying drawings and examples.

As shown in Figure 2 and Figure 3, the concave arc shape double fluid of the utility model is by detection bar 2, stagnation pressure tube to mean velocity tube flowmeter 3, the differential pressure device that static tube 4, pitot hole 5 and static pressure hole 6 form.Concave arc shape double fluid to mean velocity tube flowmeter be one diametrically Hollow metal bar, that is, detection bar 2 in insertion measurement pipeline, meeting stream direction at it has pairs of pitot hole 5 to measure stagnation pressure, all Pitot hole 5 is connected with stagnation pressure tube 3, draws average total pressure p from 3 top of stagnation pressure tube₁.There is measurement static pressure in 2 lee side of detection bar Pairs of static pressure hole 6, communicated with static tube 4, from the top of static tube 4 draw static pressure p₂.Concave arc shape double fluid is to even speed tube flow Meter utilizes the stagnation pressure p measured₁With static pressure p₂Difference reflection pipeline section on mean flow rate size.

According to Bernoulli equation, ignores the factors such as frictional resistance, fluid height difference, then have

In formula: ρ-fluid density, (kg/m³)；v₁Flow velocity at-pitot hole 5, (m/s)；p₁It is quiet at-pitot hole 5 Pressure, (Pa)；v₂Flow velocity at-static pressure hole 6, (m/s)；p₂Static pressure at-static pressure hole 6, (Pa).

Potential energy is converted to the kinetic energy of 5 internal flow of pitot hole of mean velocity tube flowmeter in concave arc shape double fluid, therefore fluid Basic stagnation, i.e. dynamic pressure are 0, therefore v₁=0, formula (1) can simplify for

Wherein: Δ p=p₁-p₂

In formula: Δ p-differential pressure, pa (Pa)；K is instrument coefficient,For the mean flow rate (m/s) of fluid.

If indicated with volume flow and mass flow, basic flow meter of the concave arc shape double fluid to mean velocity tube flowmeter Calculating formula is

q_m=q_vρ (5)

In formula: q_vThe volume flow of-fluid, (m³/s)；q_mThe mass flow of-fluid, (kg/s)；

Flow velocity coefficient of expansion when fluid flows through detection bar 2 under ε-working condition, for Incoercibility fluid:

ε=1；For compressible fluid: ε < 1；1 inner section area of pipeline, (m are measured under A-working condition²)。

The ways of measure pressure scheduling theory of working principle, pitot hole and static pressure hole based on mean velocity tube flowmeter is analyzed, using meter Fluid operator Mechanics Simulation (CFD) method, influence of the research detection bar cross sectional shape to measurement pipeline interior flow field and differential pressure signal. As shown in table 1, different Fluid Mechanics Computation simulation models is obtained by changing each structural parameters on concave arc shape detection bar section, Flow field simulation is carried out to each model and extracts in detection bar stagnation pressure and static pressure to calculate differential pressure value.As shown in figure 4, each by analysis Concave arc shape detects the flow field velocity cloud atlas that rod model generates inside measurement pipeline, shows the detection bar under same measurement caliber Circumscribed circle diameter L1 is bigger, and in the thicker phenomenon in the boundary layer that detection bar downstream generates, the differential pressure value accordingly obtained is bigger.Such as figure 5, shown in Fig. 6, Fig. 7 simulation result, the size of each structural parameters concave arc radius R1 is to differential pressure value on concave arc shape detection bar section Influence specific gravity highest, other parameters such as detection pole length D, convex arc radius R2, convex arc width L2, berm width t and pressure port Influence away from Δ L to differential pressure value is smaller, can be adjusted accordingly according to actual use operating condition and processing technology level.

The utility model according to model 7 structural parameters obtain preferable static test calibration result it is as shown in table 2, compared with Big range ability internal difference is pressed with apparent increase, reaches 65Kpa or more under 5m/s fluid flow rate；Flow measurement repeatability, line Property degree it is preferable, repeatability within 0.5%, the efflux coefficient linearity reaches within 2%.Emulation data and measured data are done pair Than utilizing the reason such as Fluid Mechanics Computation emulation and even speed tube working principle to demonstrate as shown in figure 8, the two is not much different By the accuracy for the research method that analysis combines.

As shown in figure 9, same measurement caliber, same detection bar circumscribed circle diameter are based on, by the utility model and diamond shape stream Calibration result of the meter under identical water flow static test compares.Under same flow velocity, the output differential pressure of the utility model It is significantly improved, therefore the utility model has apparent measurement advantage in biggish flow measurement range, especially to raising The measurement accuracy of small flow produces bigger effect.

The different concave arc shape detection bar cross sectional shape simulation models of table 1

2 concave arc shape double fluid of table is to mean velocity tube flowmeter in DN100 water flow nominal data

Claims (4)

1. a kind of concave arc shape double fluid is to mean velocity tube flowmeter, including being diametrically inserted into the detection bar measured in pipeline, setting is being examined Stagnation pressure tube and static tube in measuring staff, stagnation pressure tube are located at fluoran stream surface, and static tube is located at lee side, in the fluoran stream surface and back of detection bar Stream interface is provided with pitot hole and static pressure hole, and all pitot holes are connected with stagnation pressure tube, draws average total pressure p from stagnation pressure tube；Institute Some static pressure holes are communicated with static tube, draw static pressure p from static tube；Pipeline is obtained using the difference of the stagnation pressure p and static pressure p measured to cut The size of mean flow rate on face, which is characterized in that for the cross sectional shape of detection bar similar to diamond shape, four sides are concave arc shape, fluoran stream surface It is convex with lee side, the side of the concave arc shape place that connects is streamlined.

2. flowmeter according to claim 1, which is characterized in that each recessed in the case where meeting processing technology requirement The curvature of arc-shaped side is the bigger the better.

3. flowmeter according to claim 1, which is characterized in that the concave arc radius (R1) and detection bar on each concave arc shape side The Ratio control of circumscribed circle diameter (L1) is 0.25~3.

4. flowmeter according to claim 1, which is characterized in that the flowmeter bilateral symmetry, stagnation pressure tube and static pressure Pipe can exchange, to realize double fluid to flow measurement.