SU834457A1

SU834457A1 - Vibration liquid density meter

Info

Publication number: SU834457A1
Application number: SU792762372A
Authority: SU
Inventors: Петр Александрович Малышев; Константин Ильич Ткаченко
Priority date: 1979-05-07
Filing date: 1979-05-07
Publication date: 1981-05-30

Description

(54) ВИБРАЦИОННЫЙ ПЛОТНОМЕР ЖИДКОСТИ(54) VIBRATION FLUID DENSITY

II

Изобретение относитс к контрольно-измерительной технике и. может использоватьс при измерени х плотности жидкости.This invention relates to instrumentation engineering and. can be used when measuring fluid density.

Известен вибрационный плотномер, содержащий сосуд с исследуемой средой и механический колебательный элемент 1.Known vibrating densitometer containing a vessel with the test medium and the mechanical oscillatory element 1.

Однако плотномер имеет низкую точность измерений, обусловленную вли нием в зкостных свойств контролируемой жидкости на гидравлическое сопротивление колебательного элемента.However, the density meter has a low measurement accuracy due to the influence of the viscosity of the controlled fluid on the hydraulic resistance of the oscillatory element.

Наиболее б.лизкий к предлагаемому вибрационный плотномер содержит сосуд с измер емой средой, механический резонатор в виде пластины и экрана также плоской формы, св занный с резонатором, регулируемый по частоте возбудитель колебаний и датчик колебаний резонатора 2.The closest to the proposed vibratory density meter contains a vessel with the measured medium, a mechanical resonator in the form of a plate and a screen, also flat in shape, connected to the resonator, a frequency-controlled exciter of oscillations and a vibration sensor of the resonator 2.

Недостатком плотномера вл етс низка точность измерений, обусловленна вли нием в зкостных свойств контролируемой жидкости на гидравлическое сопротивление колебательного элемента. /The disadvantage of the densitometer is the low measurement accuracy due to the viscosity effect of the controlled fluid on the hydraulic resistance of the vibrating element. /

Цель изобретени - повышение точности измерений.The purpose of the invention is to improve the measurement accuracy.

Поставленна цель достигаетс тем, что в вибрационном плотномере жидкости, содержащем емкость, механический резонатор, датчик Колебаний и регулируемый возбудитель колебаний резонатора, емкость жестко св зана с возбудителем колебаний резонатора , который выполнен упругим и объемно сжимаемым, причем плотность жидкости, резонансна , частота колебаний резонатора и конструктивные параметры плотномера св заны соотношениемThe goal is achieved by the fact that in a vibration densitometer of a liquid containing a capacitance, a mechanical resonator, an oscillation sensor and an adjustable resonator vibration exciter, the capacitance is rigidly connected to the resonator vibration exciter, which is elastic and volumetric compressible, and the density of the liquid is resonant, the resonator frequency and design parameters of the densitometer are related by

К,TO,

--гг- yy

fz-Kjfz-kj

Р - определ ема плотностьР - determined density

гдеWhere

жидкости;liquids;

f - резонансна частота колебаний резонатора;f is the resonant frequency of the resonator;

Кч п8Ра/4зг УН - посто нные коэффициенHK2 hSg/47r2V ты;Kch p8Pa / 4zg UN - constant coefficientsHK2 hSg / 47-2V;

гдеп - показатель политропыwheredep is an indicator of polytropic

заполн ющего резонатор газа;gas filling the resonator;

S - площадь поперечного сечени емкости;S is the cross-sectional area of the tank;

Claims

PO is the gas pressure above the free surface of the liquid; V is the volume of gas in the resonator; h is the depth of immersion of the resonator; g - free fall acceleration. Vibrating densitometer is shown schematically in the drawing. The densitometer contains a container 1, completely or partially filled with the liquid under study 2 and rigidly connected with the exciter 3 oscillations. The container 1 has the possibility of reciprocating motion and contains a mechanical resonator 4, made in the form of a volume-compressible elastic body, for example, a gas-filled ball with elastic walls. In the liquid, the sensor 5, made, for example, of a piezocrystal, which functions as a transducer for the hydrodynamic pressure of the liquid into an alternating current electrical signal, is preferably located at the level of the location of the resonator 4. The output circuit of sensor 5 is connected to the input of a millivolt amplifier, meter 6, and then to a frequency meter 7. The device operates as follows. When the oscillator is switched on, the vibrator table 3, as well as capacitance 1 and WIL / 1 / I DflVyi / VJ - П .LClCl I I V., holding fluid 2 with it, make oscillating periodic movements, for example, in a vertical plane (shown by arrows) . Fluid vibrations are transmitted to the resonator 4, which begins to perform radial pulsations, in which the volume of the resonator 4 periodically, with the frequency of external influences, changes due to the compressibility of the walls of the resonator 4 and the gas filling it. When the frequency of external effects coincides with the natural frequency of oscillations of the resonator 4, a resonant mode occurs, accompanied by a sharp increase (by 10–15 times) in the amplitude of the pulsations. The pulsation movements of the resonator 4 cause a proportional increase in the hydrodynamic pressure of the fluid in the vicinity of the resonator 4. The pressure is converted by the sensor 5 into an alternating current electrical voltage, which is amplified by the amplifier 6. The frequency of the electrical signal is recorded by the frequency meter 7. The accelerometer, usually mounted on table vibrost nda. To measure the density of the fluid, where the frequency of the oscillator 3 oscillations changes while accelerating the vibration is constant, a mode of movement is found at which the readings of millivoltmeter b have the maximum value. In this mode, the readings of the frequency meter 7 are recorded. By which the density of the liquid is judged. Estimation of the density as a function and the measured resonant frequency and constructive parameters, Ki parameters of the mechanical oscillatory system can be made according to the following relation; where is the density of the liquid; K., nSPa / 4T Vh - constant coefficients of Kj. nSg / 4s-2V you; n is the polytropic index for the gas filling the resonator (n 1 -1.4 for air); V is the volume of gas in the resonator, h is the depth of immersion of the resonator, m; S is the cross-sectional area of the capacitance, RI is the gas pressure above the free surface of the liquid, g is the acceleration of free fall, f is the resonant frequency of pulsation oscillations of the resonator, Hz. From the above expression, it can be seen that the realized oscillatory process is involved / mass forces, and the forces of viscous friction and the temperature of the liquid do not affect the measurement result. Thus, the proposed technical solution has the advantage of increasing measurement accuracy. The device is distinguished by the simplicity of the circuit design, ease of use and the possibility of using it in conditions of small and strong gravitational fields. Vibration Fluid Densimeter containing a capacitor, a mechanical resonator, an oscillation sensor, and an adjustable resonant resonant vibration characterized by the fact that, in order to improve the measurement accuracy, the capacitance is rigidly connected to the resonator vibration exciter, which is made elastic and volumetric compressible, moreover, the density of the liquid, the resonant frequency of oscillations of the resonator and the design parameters of the densitometer are related by the ratio. J is the fluid density; f is the resonant frequency of the resonator; Pa / 4. - constant coefficient g / 4Jr2V you; n is the polytropic index for the gas filling the resonator; S is the cross-sectional area of the tank;