JPH08334394A - Flow rate measuring instrument - Google Patents

Abstract

PURPOSE: To measure the quantity of liquid of a jetted multiphase flow separately from the quantity of gas jetted in terms of a flow rate measuring instrument that measures the flow rate of the liquid in the multiphase flow jetted from a mixing chamber that mixes the gas with the liquid. CONSTITUTION: The title instrument comprises a flow rate sensor 20 that measures a flow rate of liquid flowing into a mixing chamber 10, a sound source 21 that applies a sound wave QOexp (jωt) to the mixing chamber 10, a pressure sensor 22 that measures a reference static pressure PO in the mixing chamber 10 and a sound pressure sensor 23 that measures a sound pressure PW of an angle frequency ω in the mixing chamber 10. The quantity of the liquid jetted of a multiphase flow is obtained by a calculation section 26, based on the above detected values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring device for measuring the flow rate of liquid in a multiphase flow injected from a mixing chamber for mixing gas and liquid.

[0002]

2. Description of the Related Art Conventionally, the above-described technology of mixing and injecting gas and liquid in a mixing chamber has been used, for example, in a device for injecting gasoline into an engine of an automobile. FIG. 3 is a schematic view of the mixing chamber. In the mixing chamber 10, a liquid (for example, gasoline) 11 and a gas (for example, air)
12 flows in, they are mixed inside the mixing chamber 10 and are jetted from the mixing chamber 10.

[0003]

For example, it has been desired to measure the temporal change in the injection amount of gasoline into the engine as described above, but until now, an appropriate measurement method has been found. Absent. For example, it is conceivable to employ a so-called momentum method in which the multiphase flow ejected from the mixing chamber 10 is sprayed on a pressure sensor or the like and the injection amount is obtained from the pressure change, but the spraying pressure of the liquid in the multiphase flow and the gas It is not possible to separate the spray pressure and therefore it is not possible to measure the ejection volume of only the liquid in the multiphase flow.

In view of the above circumstances, it is an object of the present invention to provide a flow rate measuring device for measuring the injection amount of liquid in an injection multiphase flow separately from the injection amount of gas.

[0005]

In a flow rate measuring device of the present invention which achieves the above object, a gas and a liquid, which are injected from a predetermined mixing chamber into which both a gas and a liquid flow, are mixed. A flow rate measuring device for measuring the ejection amount of a liquid in a multi-phase flow, comprising: (1) a flow rate sensor for measuring the flow rate of the liquid flowing into the mixing chamber (2) a volume for measuring the volume or change in volume of gas in the mixing chamber. Sensor (3) It is characterized by comprising an arithmetic unit for determining the ejection amount of the liquid in the multiphase flow based on the flow rate measured by the flow rate sensor and the volume or volume change measured by the volume sensor.

In the flow rate measuring device of the present invention, the volume sensor of (2) above is (2-1) a sound source that emits a sound wave containing at least a predetermined frequency into the gas in the mixing chamber. 2) Pressure sensor for measuring pressure in the mixing chamber (2-3) It is preferable to include a sound pressure sensor for measuring sound pressure at a predetermined frequency in the mixing chamber.

[0007]

FIG. 1 is a diagram for explaining the principle of the present invention, in which various symbols are added to the schematic diagram of the mixing chamber shown in FIG.
Although the flow rate measuring device of the present invention is not applied only to the rectangular mixing chamber and the like as shown in FIG. 1, the measurement of the present invention will be described below with reference to FIG. 1 for the sake of easy understanding. The principle will be described.

In the system shown in FIG. 1, the volumetric velocity of the liquid 11 flowing into the mixing chamber 10 is Q _{L, in} (t), the internal volume of the mixing chamber 10 is V _O , and the volume of the liquid 11 in the mixing chamber 10 is V _L (t), the volume of the gas in the mixing chamber 10 V _G (t), the flow volume rate of liquid in multiphase flow ejected from the mixing chamber 10 Q _{L, out}
(T). Note that (t) represents a function of time t. What is being sought here is the outflow volume velocity Q _{L, out} (t) of the liquid.

Volume V _L of liquid 11 in mixing chamber 10
(T) is, because it is given by _{V L (t) = V O} -V G (t) ...... (1),

[0010]

[Equation 1]

According to the above, the outflow volume velocity of the liquid in the jet multiphase flow is
Degree Q_{L, out} (T) is estimated. However, here
The body 11 is assumed to be an incompressible fluid. Ie
According to the equation (2), the flow of the liquid 11 flowing into the mixing chamber 10
Volumetric velocity Q _{L, in}(T) and the gas 12 in the mixing chamber 10
Volume V_G (T) or its volume change {dV_G (T) /
dt} and the fluid in the jet multiphase flow
Outflow volume velocity Q_{L, out} (T) can be obtained.

(Measurement of Liquid Inflow Volume Velocity Q _{L, in} (t)) Since this is the liquid inflow volume velocity in the state where only the liquid is flowing in the liquid inflow pipe 13, for example, a laser Doppler velocity meter, Liquid 11 by ultrasonic velocity meter
The flow velocity V _{L, in} (t) of the pipe 13 is measured, and the inner cross-sectional area of the pipe 13 (see FIG. 1) is S and the correction coefficient is α. Q _{L, in} (t) = α · S · V _{L, in} ( t) It can be calculated by (3). The method itself for obtaining the volume velocity of the liquid flowing in the liquid inflow pipe 13 has been conventionally known, and the velocity meter based on various principles has been conventionally known. Here, more detailed description will be given here. Is omitted.

(Measurement of Volume or Volume Change of Gas in Mixing Chamber) The present invention does not limit the method itself for obtaining the volume or volume change in the mixing chamber to a specific method. The volume or volume change may be measured by continuously forming an image of the inside of the mixing chamber 10 and performing image processing, but here, for example, the injection of gasoline described above is performed. A method of measuring the volume of gas based on the following principle will be described as a method capable of knowing a high-speed flow rate change in units of several msec, for example.

In the mixing chamber 10, an angular frequency ω and a volume velocity Q
_O waves Q _O gives exp gas to sonic (pressure change) in place sound sources for generating (j? T) and the mixing chamber 10 of the pressure P _O of the gas in the mixing chamber 10, the sound of the angular frequency ω Pressure P
Measure _W exp (jωt). In addition, j represents an imaginary unit. Here, the typical length in the mixing chamber 10 is the sound wave Q.
_It is assumed to be sufficiently smaller than the wavelength of _O exp (jωt).

Assuming that the density of the gas 12 inside the mixing chamber 10 is ρ and the particle velocity (vector) is v,

[0016]

[Equation 2]

It is represented by Further, the pressure of the gas 12 in mixing chamber 10 is P, as in _{P = P O + p ρ =} ρ O + ρ'v = v O + v'= v'...... (5), a parallel state Pressure P _O , density ρ _O , velocity v _O
And the deviation p (sound pressure), ρ ′, and v ′ from it. However, regarding the particle velocity v, it is assumed that there is no gas flow in the equilibrium state, and therefore the particle velocity v _O is v
_{Let O} = 0.

Substituting equation (5) into equation (4), P _O ,
Since ρ _O is a constant value,

[0019]

(Equation 3)

[0020] The third term v'on the left side of the equation (6)
・ Grad (ρ ') is a second-order minute quantity, so if omitted,

[0021]

[Equation 4]

Is satisfied. Further, from thermodynamic consideration, we consider gas density ρ as a function of pressure P and entropy S ρ = ρ (P, S) (7), and the isentropic process in which the effects of heat conduction and viscosity can be ignored. Thinking,

[0023]

(Equation 5)

Here, 'o' of (...) _{S, O} is a value in the equilibrium state. Equation (7) is

[0025]

(Equation 6)

[0026] Next, the above equation (9) is applied to the mixing chamber 10
Over a portion (V _G ) of the gas 12 of Here, as described above, when the length dimension of the mixing chamber 10 is sufficiently smaller than the wavelength of the sound wave, the sound pressure may be considered to be uniform inside the mixing chamber 10,

[0027]

(Equation 7)

However, x represents a vector. Now, by integrating equation (9) within V _G ,

[0029]

(Equation 8)

To obtain However, for simplicity, the sound source is a plane piston sound source, and the normal component of the vibration velocity of the sound source is V _n · e
xp (jωt), the area of the sound source is A, and P = P _W exp (jωt), and the common factor exp (jωt) is omitted. (11)
From the formula,

[0031]

[Equation 9]

Q _O = −A · V _n (13) is obtained. In case of ideal gas,

[0033]

[Equation 10]

And the equation (12) is

[0035]

[Equation 11]

It becomes Therefore

[0037]

(Equation 12)

To obtain Up to now, V _G and P _O are constant, but when these change slowly compared to exp (jωt), V _G → V _G (t), P _O → P _O (t) ... … (18) Also, (5) was the expression since v _O = 0, for the same reason that the influence of the heat conduction gas was assumed as negligible in (10), the density ρ = ρ ₀ + ρ 'in the mixing chamber If it is considered that the spatially uniform variation occurs, and if the temporal variation of the sound wave is sufficiently faster than the temporal variation of the background P ₀ (t), etc., then in the case of v _O ≠ 0, (7) The formula will hold.

Here, in the above equation (17), the volume velocity Q _O of the sound source is a measurable and controllable amount, and the pressure P _O ,
The sound pressure P _{W is} also a measurable amount. By the way, the specific heat ratio γ shown in the equation (17) is good in the case of an ideal gas, but in reality, the heat conduction between the inner wall of the mixing chamber 10 and the gas cannot be ignored. Therefore, the above equation (17) is changed to

[0040]

(Equation 13)

Rewrite as Where γ_eff At low frequencies
γ_eff ≒ 1, γ at high frequency_eff A complex value such that ≈γ
It is a dimensionless quantity to be taken. This γ_eff Is a simple sphere or cylinder
Although it can be easily calculated in the case of a simple boundary condition, it is shown in Fig. 1.
For complex systems such as
I can't ask. Therefore, the internal shape of the mixing chamber 10
Shape, stirring state, and γ_eff Relationship map with measured data
Γ obtained from the relationship map
_eff Using V _G It is desirable to estimate

In this way, the liquid based on the equation (3) is used.
Inflow volume velocity Q_{L, in}(T) is calculated and (1
Based on equations (7) to (19), the gas inside the mixing chamber
Volume V _G From the formula (2), the injection mixed phase can be obtained by
Outflow volume velocity Q of liquid in flow_{L, out} (T) is required
It In the above description, the volume V inside the mixing chamber 10 is_O age
Is determined only by the geometrical shape inside the mixing chamber 10.
The volume is assumed, but if necessary, the geometrical volume is substituted.
Alternatively, an effective volume may be assumed. If necessary
The acoustic flow in the flow path of the gas 12 flowing into the mixing chamber 10.
May be attached.

[0043]

Embodiments of the present invention will be described below. FIG. 2 is a schematic diagram showing a state in which an embodiment of the flow rate measuring device of the present invention is attached to the mixing chamber shown in FIG. This figure 2
The code entered therein has the same meaning as the code entered in FIG. 1 or FIG. 3 or the code expressed in each of the above-mentioned formulas, and the duplicate description will be omitted here.

The liquid inflow pipe 13 is provided with a laser Doppler velocity meter (LDV) 20 for measuring the flow velocity of the liquid 11 flowing inside the pipe 13, and the flow velocity V _{L, in} (t) is obtained, In the calculation unit 26, the inflow volume velocity QL _{, in} (t) of the liquid 11 is obtained based on the input flow velocity _{VL, in} (t) according to the above-described equation (3). In the present embodiment, the flow sensor according to the present invention has a configuration in which the LVD 20 and the function of converting the flow velocity V _{L, in} (t) of the calculation unit 26 into the inflow volume velocity QL _{, in} (t) are combined. Correspond.

A sound source 21, a pressure sensor 22, and a sound pressure sensor 23 are provided on the wall of the mixing chamber 10. The pressure sensor 22 measures the static pressure of the gas 12 inside the mixing chamber 10 (or a quasi-static pressure that changes slowly compared to exp (jωt)), and the sound pressure sensor 23 measures the pressure of the angular frequency ω. It measures changes. Here, the pressure sensor 22 and the sound pressure sensor 2 are distinguished by name.
As long as 3 satisfies each purpose, it may have the same specifications as long as each purpose is satisfied. In that case, there is only one part that directly measures the pressure or sound pressure of the gas, and the pressure (static pressure or quasi-static pressure) is set by a filter or the like.
And sound pressure (angular frequency ω).

The sound source 21 has a surface (area A) on the inner side of the mixing chamber 10 in accordance with the drive signal D input to the sound source and has a surface area Q _O.
It vibrates at exp (jωt). The drive signal D is input to the arithmetic unit 26 as a signal carrying information on the amplitude Q _O. The pressure sensor 22 is a sensor for measuring the pressure of the gas 12 inside the mixing chamber 10. The output signal from the pressure sensor 22 is input to the low-pass filter 24 and is a signal representing static pressure or quasi-static pressure P _O. Is extracted and the calculation unit 2
6 is input.

The sound pressure sensor 23 is a sensor for measuring the sound pressure P _W of the gas 12 inside the mixing chamber 10 at the angular frequency ω, and the output signal from the sound pressure sensor 23 is a bandpass signal. The sound pressure P of the angular frequency ω is input to the filter 25.
_A signal representing _W is extracted and input to the arithmetic unit 26.
Data about γ _eff measured in advance in the system shown in FIG. 2 is stored in the calculation unit 26,
In the calculation unit 26, the volume V _G (t) of the gas inside the mixing chamber 10 is obtained based on the above-mentioned equation (19).

In this way, in the calculation unit 26, the liquid 1
1 inflow volume velocity Q _L, and _in (t), the volume V _G of the gas inside the 12 (t) is obtained in the mixing chamber 10, further outflow volume velocity of the liquid 11 on the basis of the foregoing equation (2) QL _{, out}
(T) is required.

[0049]

As described above, according to the present invention,
The injection amount of the liquid in the injection multiphase flow can be measured separately from the injection amount of the gas.

[Brief description of drawings]

1 is a diagram illustrating the principle of the present invention, in which various symbols are added to the schematic diagram of the mixing chamber shown in FIG.

FIG. 2 is a schematic view showing a state in which an embodiment of the flow rate measuring device of the present invention is attached to the mixing chamber shown in FIG.

FIG. 3 is a schematic view of a mixing chamber.

[Explanation of symbols]

 10 Mixing chamber 11 Liquid 12 Gas 13 Liquid inflow pipe 20 Laser Doppler velocity meter 21 Sound source 22 Pressure sensor 23 Sound pressure sensor 24, 25 Filter 26 Calculation unit

Claims (2)

[Claims] 1. A flow rate measuring device for measuring the ejection amount of a liquid in a multiphase flow in which a gas and a liquid are mixed and which is ejected from a predetermined mixing chamber into which both the gas and the liquid flow. A flow sensor for measuring the flow rate of the liquid flowing into the mixing chamber, a volume sensor for measuring the volume or volume change of the gas in the mixing chamber, the flow rate measured by the flow sensor and the volume sensor. A flow rate measuring device, comprising: a calculation unit that determines the ejection amount of the liquid in the multiphase flow based on the volume or the volume change. 2. The sound source for emitting a sound wave having at least a predetermined frequency into the gas in the mixing chamber, the pressure sensor for measuring the pressure in the mixing chamber, and the predetermined sensor in the mixing chamber. The sound flow sensor according to claim 1, further comprising: a sound pressure sensor that measures sound pressure of the frequency.