CN105783985A - Ultrasonic doppler technology-based gas-liquid two-phase flow measuring method and device - Google Patents

Abstract

The present invention provides an ultrasonic doppler technology-based gas-liquid two-phase flow measuring method and a device. Based on the method and the device, the phase content, the speed and the flow of each of the gas-phase flow and the liquid-phase flow can be recognized. Meanwhile, the overall average speed and the overall flow of the gas-phase flow and the liquid-phase flow can be recognized. The device comprises a measuring pipe (1), an ultrasonic signal transmitter (2), an ultrasonic signal receiver (3), a data acquisition and processing system (4), a control computer (5) and a differential pressure flowmeter (6). The device can be used for recognizing the phase content, the speed and the flow of each of the gas-phase flow and the liquid-phase flow, the overall average speed and the overall flow of the gas-phase flow and the liquid-phase flow.

Description

Gas-liquid two-phase flow measuring method and device based on ultrasonic Doppler technique

Technical field

The present invention relates to field of fluid measurement, specifically a kind of gas-liquid two-phase flow measuring method based on ultrasonic Doppler technique and device.The method and device may identify which each phase content of biphase gas and liquid flow, speed and flow and bulk flow velocity, flow.

Background technology

Engineering is widely present the flow phenomenon of two phase flow, wherein general with biphase gas and liquid flow.Such as in petroleum transportation pipeline, around hydroturbine rotor, the intracloud convection current of air etc., broadly fall into biphase gas and liquid flow flowing.Measured by two phase flow flow parameter, understand its characteristic and Changing Pattern, related scientific research, design and production tool are of great significance.Compared with single-phase flow, two phase flow owing to alternate there is mass transfer boundary is each, even chemical reaction, and in time, spatially variable at random, making the detection more complexity of such as each phase content, flow velocity, flow and the flow parameter such as overall rate, flow, difficulty is very big.Up to now, existing detection technique and method are built upon the detection means on single-phase sensor integration mostly, it is thus achieved that quantity of information little, and the overall permanence of two phase flow cannot be carried out real-time monitored description.

Parameter and the form of expression that the measurement of biphase gas and liquid flow relates to are as follows:

1. flow

(1) mass flow of biphase gas and liquid flow:

G=G_g+G_l,

Wherein, G total mass flow rate；G_gAnd G_lRespectively gas phase and liquid phase quality flow.

(2) volume flow of biphase gas and liquid flow:

Q=Q_g+Q_l,

Wherein, Q total volumetric flow rate；Q_gAnd Q_lRespectively gas phase and liquid phase volume flow.

2. flow velocity

(1) gas-liquid divides phase velocity

$w_g=\frac{Q_g}{A_g};w_l=\frac{Q_l}{A_l},$

Wherein, w_gAnd w_lRespectively gas phase and liquid phase component velocity；A_gAnd A_lThe sectional area that respectively gas phase and liquid phase fluid pass through.

(2) gas-liquid divides phase superficial velocity

$w_{\mathrm{sg}}=\frac{Q_g}{A};w_{\mathrm{sl}}=\frac{Q_l}{A},$

w_sgAnd w_slRespectively gas phase and liquid phase superficial velocity；Actual internal area

A=A_g+A_l。

3. density

(1) flow density

${\mathrm{\ρ}}_f=\frac{G}{Q}.$

(2) real density

ρ=α ρ_g+(1-α)ρ_l,

Wherein, ρ_gAnd ρ_lRespectively gas phase and liquid phase fluid density；α is void fraction, also referred to as voidage.

4. void fraction

(1) void fraction (voidage)

$\mathrm{\α}=\frac{A_g}{A}.$

(2) filling-emptying model

$\mathrm{\β}=\frac{Q_g}{Q}.$

(3) mass gas content rate

$\mathrm{\χ}=\frac{{\mathrm{\β\ρ}}_g}{{\mathrm{\β\ρ}}_g+(1-\mathrm{\β}){\mathrm{\ρ}}_l}.$

Requirements at the higher level along with metering for two phase flow in commercial production, control aspect, it is necessary to exploitation one can measure each phase content, flow velocity and flow in acquisition biphase gas and liquid flow and the device of bulk flow velocity, flow simultaneously.

Ultrasonic Doppler technique (UltrasonicDoppler) can realize visualization, noncontact, radiationless, low cost measurement, and the application in fluid measurement in recent years obtains very big development.Specifically the application principle in gas-liquid two-phase flow measurement is: utilize ultrasonic transmitter to launch the ultrasonic signal being fe to biphase gas and liquid flow flow field tranmitting frequency, when measuring volume when there being bubble to enter, owing to gas-liquid surface has very strong reflection to ultrasonic, ultrasonic echo signal fr is attenuated, and the difference fd of fe and fr, being Doppler frequency shift, it is directly linear with bubble velocity.Thus, record ultrasonic doppler frequency displacement in flow field, local gas phase velocity can be obtained.

Continuous print measures point mutually each phase velocity and the flow that can also obtain aforementioned biphase gas and liquid flow, if being equipped with multiple other kinds of sensor, it is achieved measurement in a closed series, then can obtain the flow parameter of complete biphase gas and liquid flow.

The present invention provides a kind of gas-liquid two-phase flow measuring method based on ultrasonic Doppler technique and device.The method and device may identify which each phase content of biphase gas and liquid flow, speed and flow and bulk flow velocity, flow.

Summary of the invention

The present invention provides a kind of gas-liquid two-phase flow measuring method based on ultrasonic Doppler technique and device.The method and device may identify which each phase content of biphase gas and liquid flow, speed and flow and bulk flow velocity, flow.Fig. 1 is based on the layout of the gas-liquid two-phase flow measuring apparatus of ultrasonic Doppler technique.Shown in figure, this device includes: measures pipeline (1), ultrasonic signal emission device (2), ultrasonic signal receivers (3), data Collection & Processing System (4), control computer (5), differential pressure flowmeter (6).Its annexation is:

Ultrasonic signal emission device (2) is arranged on the tube wall of the measurement pipeline (1) of tested biphase gas and liquid flow flowing；

Ultrasonic signal receivers (3) is arranged on ultrasonic signal emission device (2) opposite；

Ultrasonic signal receivers (3) connects data Collection & Processing System (4)；

Differential pressure flowmeter (6) is positioned in measurement pipeline (1), in the downstream of ultrasonic signal emission device (2)；

Control computer (5) and connect ultrasonic signal emission device (2), ultrasonic signal receivers (3), data acquisition and procession system

System (4).

Fig. 2 is the schematic diagram that ultrasonic Doppler technique measures each phase content of biphase gas and liquid flow.Representing in figure, on the section measured in pipeline (1) on two phase flow direction, measuring pipeline both sides and dispose ultrasonic signal emission device (2), ultrasonic signal receivers (3) is installed on its opposite.In the process measured, impulse ultrasound signal (7) launched by ultrasonic signal emission device, when measuring two phase flow in pipeline, being continually changing of bubble (9) and liquid (8) each phase content and distribution, owing to ultrasonic measurement volume has a certain size, the Moving Bubble of all of which all can produce doppler shifted signal, and ultrasonic signal receivers (3) receives signal and provides the result after all signals in this measurement volume are averaged.Data Collection & Processing System (4) is analyzed by echo signal carries out fast Fourier transform (FFT), the spectrogram of Doppler frequency shift can be obtained, thus obtaining the spectrum distribution of speed, in gas-liquid two-phase flow, there is obvious sliding velocity between liquid and gas, in the FFT speed spectrum provided is distributed, is presented as obvious bimodal distribution.Through digital filtering and FFT inverse transformation, obtain point phase velocity of gas-liquid two-phase respectively.

Accompanying drawing explanation

Fig. 1 is based on the layout of the gas-liquid two-phase flow measuring apparatus of ultrasonic Doppler technique；In figure, 1 measures pipeline, 2 ultrasonic signal emission devices, 3 ultrasonic signal receivers, 4 data Collection & Processing Systems, 5 control computer, 6 differential pressure flowmeters.

Fig. 2 is the schematic diagram that ultrasonic Doppler technique measures each phase content of biphase gas and liquid flow；In figure, 1 measures pipeline, 2 ultrasonic signal emission devices, 3 ultrasonic signal receivers, 7 ultrasonic signals, 8 liquid, 9 bubbles.

Detailed description of the invention

With a specific embodiments further illustrate that the present invention proposes based on the gas-liquid two-phase flow measuring method of ultrasonic Doppler technique and the principle of device and structure.The method and device are for measuring each phase content of Air-C_2H_2 Flame, speed and flow and bulk flow velocity, flow.Parts composition in this device is identical with Fig. 1 with annexation.

In detailed description of the invention,

The cross section measuring pipeline (1) is square, for length be 1m, inner edge is 50mm, wall thickness 10mm, material are lucite.Horizontal positioned.

Ultrasonic signal launched by ultrasonic signal emission device (2), and transmission Air-C_2H_2 Flame fluid produces Doppler frequency shift；

Data Collection & Processing System (4) measures Doppler frequency shift, carries out data process, it is thus achieved that obtain Gas-water phases stream flow field in the transient components measured；

Controlling the operation that computer (5) connects, controls data Collection & Processing System (4), the continuous print sampling interval of specified data collection simultaneously and the system of process (4), thus obtaining point phase velocity of Air-Water；

The downstream of pipeline (1) measured by differential pressure flowmeter (6), measures total flow.

Claims (2)

1. the gas-liquid two-phase flow measuring method based on ultrasonic Doppler technique and device, the method and device include measuring pipeline (1), ultrasonic signal emission device (2), ultrasonic signal receivers (3), data Collection & Processing System (4), controlling computer (5), differential pressure flowmeter (6), with the annexation of upper-part are:

Ultrasonic signal emission device (2) is arranged on the tube wall of the measurement pipeline (1) of tested biphase gas and liquid flow flowing；

Ultrasonic signal receivers (3) is arranged on the tube wall measuring pipeline (1)；

Ultrasonic signal receivers (3) connects data Collection & Processing System (4)；

Differential pressure flowmeter (6) is positioned in measurement pipeline (1), in the downstream of gamma-rays emitter (2)；

Control computer (5) and connect ultrasonic signal emission device (2), ultrasonic signal receivers (3), data Collection & Processing System (4).

2. a kind of gas-liquid two-phase flow measuring method based on ultrasonic Doppler technique according to claim l and device, it is characterized in that, described ultrasonic signal emission device (2) and ultrasonic signal receivers (3) are separately mounted to measure the opposite of pipeline (1).