RU135148U1 - MOBILE INSTALLATION FOR MEASURING SPEED AND DIRECTIONS OF WATER FLOW IN OPEN WATERS - Google Patents

Abstract

A mobile device for measuring the speed and direction of the flow of water in open streams, containing a working fluid suspended from rotation around a vertical axis, a means of measuring deviations from the vertical of the working fluid, means of determining the direction of flow, characterized in that a metal ball is used as the working fluid, suspended on a flexible medium, moreover, the medium is labeled and attached to a rod made with metric marking, and the means for determining the direction of flow, which is about At the same time, a means for visual measurement of the deviation of the ball from the vertical is made in the form of a shield with a graduated scale applied on it and mounted on a bar with the possibility of rotation around it under the influence of a water stream.

Description

The utility model relates to the field of measuring the velocity of fluids and indicating the direction of movement of water flows and can find applications for measuring the flow velocity in small rivers, streams, channels for the subsequent calculation of roughness coefficients, water flow rates and hydraulic calculations.

The closest analogue is a device for determining the speed and direction of fluid flow (RU 2413232, IPC G01P 5/06, G01V 1/38, 001815/58, G01C 17/32, published on September 20, 2010) containing a measuring unit connected in series , a receiving unit and an information recording and processing unit, wherein the measuring unit is made in the form of a sealed enclosure with blades, balancing the float with an adjusting weight, a speed sensor and a suspension unit mounted on a rigid carrier equipped with a cable line and configured to rotate the measuring block around a vertical axis. The housing is equipped with a signal processing and transmission system containing a sensor deviation from the direction of the magnetic field. The signal processing and transmission system is digital, it additionally contains a vertical deviation sensor made in the form of a biaxial inclinometer, while the deviation from the magnetic field direction is a three-axis electronic compass, and the suspension unit is designed to swing around a horizontal axis.

The disadvantages of the above device can be attributed to its high cost, due to the complexity of its manufacture due to the need to make the case airtight and an energy source for operation, which limits its use in preliminary hydraulic calculations.

The utility model solves the problem of reducing the cost of a device for determining the speed and direction of fluid flow by simplifying its design due to the use of a visual method of measuring the deviation of the working fluid from the vertical and applying the found deviation in the calculations to determine the speed.

To achieve the desired technical result in a known device for measuring the speed and direction of the flow of water, containing a working fluid suspended from the vertical axis, means for measuring deviations from the vertical of the working fluid, means for determining the direction of flow, it is proposed to use a metal ball as a working fluid, suspended on a flexible carrier, the carrier being provided with a mark and attached to a rod made with metric marking, and the means for determining the flow phenomena, which is simultaneously a means for visually measuring the deviation of the ball from the vertical, made in the form of a shield with a graduated scale applied on it, and fixed on the bar with the possibility of rotation around it under the influence of a water stream.

The attached diagrams show:

figure 1 - the proposed device in a calm state;

figure 2 - the deviation of the working fluid from the vertical;

figure 3 - the forces acting on the working fluid, when it deviates from the vertical.

The following notation is used in the diagrams:

1 - free water level; 2 - a bar marked on decimeters; 3 - carrier; 4 - a shield with a graduated scale; 5 - label on the medium; 6 - a ball; 7 - bottom of the watercourse, 8 - support, h - height of the mark on the carrier under the influence of the current; h ₁ - the height of the ball under the action of the current; l is the distance from the carrier attachment point to the mark (radius of rotation of the mark); l ₁ is the length of the carrier; T is the carrier tension force; G is the gravity of the ball in water; F is the force of the hydrodynamic resistance of the ball to the flowing stream; β is the angle of deviation of the carrier relative to the vertical;

In the proposed device (figure 1), the determination of the speed and direction of the flow of water is as follows.

The device is installed vertically and secured to the bottom 7 of the watercourse using the support 8. The shield 4, which serves as a means of determining the direction of the flow of water, is made with metric marking, decimetric marking was used in the prototype. Under the influence of the water flow, the shield 4, mounted on the rod 2 with the possibility of rotation around the rod 2, rotates and is installed parallel to the water flow, thereby showing the direction of the flow like a weather vane.

Under the influence of the hydrodynamic forces of the flowing water acting on the ball 6, the carrier 3 deviates from its original vertical position. By determining the height by which the mark 5 on the carrier 3 with respect to the horizontal plane is determined by the graduated scale of the shield 4, the speed of the water flow can be calculated.

The device is designed to measure the flow velocity over the entire range of real flow velocities of flat rivers from 0.1-1 m / s. In the prototype, the diameter of the ball was 2 cm, it is better to choose aluminum as the material for the ball, because at a higher density of the ball material in the indicated range of flow velocities, the deviation angles will be small, which will complicate the visual measurement. The height of the rod was 1.5 m. Methodology and calculation example.

The value of kinematic viscosity at a temperature of 20 ° C, υ = 10 ⁶ m ^{2 /} s. In the range of Reynolds numbers Re from 10 ³ to 10 ^{5 the} value of the resistance coefficient C is almost stable and can be taken equal to 0.46 (L. Prandtl Hydroaeromechanics. - M .: Publishing house of foreign literature, 1949. - 529 s).

In the range of the diameter of the ball from 1 to 3 cm and water flow velocities from 0.1 to 3 m / s, the Reynolds numbers take values from 10 ³ to 10 ³ .

Consider the balance of a ball 6 of diameter d suspended on a carrier 3, part of which, together with the ball 6, is immersed in water (Fig. 1). The length of the carrier 3 is l ₁ , the distance from the mounting point of the carrier 3 to the mark 5 (radius of rotation of the mark) l, the ball 6 rises to a height h ₁ under the action of the flow, the mark 5 on the carrier rises to a height h under the action of the flow (Fig. 2) .

The ball 6 is affected by the tension force of the carrier 3 equal to T, the gravity of the ball 6 in water is G and the hydrodynamic resistance of the ball 6 to the flowing fluid is F (Fig. 3).

The forces acting on the carrier are not taken into account.

We project the forces acting on the ball on the x and y axes. We get

Where:

F is the force of the hydrodynamic resistance of the ball to the flowing stream, H;

T is the carrier tension force, H;

β — carrier deflection angle relative to the vertical, degrees;

G is the gravity of the ball in water, H;

From the expressions (1), (2) we obtain

The known force of the hydrodynamic resistance of the ball to the flowing fluid flow F

where: C - resistance coefficient (Prandtl L. Hydroaeromechanics. - Izhevsk: Research Center “Regular and chaotic dynamics”, 2000, pp. 260-261);

ρ _in - the density of water, kg / m;

V is the velocity of the water flow in the river, m / s;

d is the diameter of the ball, m;

π - 3.14.

Gravity of a ball in water G

where: ρ _W - the density of the material of the ball, kg / m;

g is the acceleration of gravity, m / s ² ;

ρ _in - the density of water, kg / m ³ ;

d is the diameter of the ball, m;

π - 3.14.

From expressions (3) - (5), the velocity of water flow in the river V

where: ρ _o = (ρ _ш / ρ _в ) is the relative density of the ball material.

According to the diagram in figure 3:

where: h is the height of the ball under the action of the current, m;

l is the length of the carrier, m

From expressions (6) - (7)

where, V is the velocity of the water flow in the river, m / s;

С - resistance coefficient (Prandtl L. Hydroaeromechanics. - Izhevsk: Research Center “Regular and chaotic dynamics”, 2000, pp. 260-261);

ρ _about = (ρ _W / ρ _in ) is the relative density of the ball material;

d is the diameter of the ball, m;

g is the acceleration of gravity, m / s ² ;

h is the height of the ball under the action of the current, m;

l is the length of the carrier, m

Consider an example calculation for an aluminum ball.

Let C = 0.46, ρ ₀ = 2.7, d = 0.02 m, g = 9.81 m / s ² , l = 0.2 m, h = 0.07 m. Let us determine the flow velocity of water V.

Substituting the given values into expression (6), we obtain

From the expression (9), V = 0.414 m / s.

The proposed utility model is extremely simple, and therefore, a very cheap mobile device for determining the values of the current velocity and direction of the current in open streams. By visually measuring the deviation of the working fluid from the vertical, the current velocity is easily calculated using the proposed technique.

Claims (1)

A mobile device for measuring the speed and direction of the flow of water in open streams, containing a working fluid suspended from rotation around a vertical axis, a means of measuring deviations from the vertical of the working fluid, means of determining the direction of flow, characterized in that a metal ball is used as the working fluid, suspended on a flexible medium, moreover, the medium is labeled and attached to a rod made with metric marking, and the means for determining the direction of flow, which is about At the same time, a means for visually measuring the deviation of the ball from the vertical is made in the form of a shield with a graduated scale applied on it and mounted on a bar with the possibility of rotation around it under the influence of a water stream.

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