Method for measuring liquid viscosity through bubble method

Abstract

The invention relates to a method for measuring liquid viscosity by a bubble method, which comprises the following steps of: under the condition that liquid stands, manufacturing a bubble ball at the bottom of the liquid, and floating the bubble ball under the action of liquid buoyancy; and meanwhile, the floating time t and the floating distance h of the small bubble ball are calculated. The introduced pollution is small, the method is simple and convenient, and compared with the same type of falling ball methods in previous patents, the small balls are easy to clean and rapidly and repeatedly measure. Therefore, the method is simpler, more convenient and more practical. Bubbles are processed into a small ball model, so that the released bubbles are spherical bubbles as much as possible, and data processing of accurate measurement is facilitated. The operation can be repeated, and the repeated operation is simple and convenient. The bubble method is suitable for non-ablative liquid with light weight and small viscosity.

Description

Technical Field

[0001] The invention relates to the measurement of liquid viscosity and provides a method for measuring liquid viscosity by using a bubble method. Relevant parameters are measured through the movement process of bubbles in the liquid to estimate the viscosity of the liquid. Background Art

[0002] Viscosity is an important physical parameter to measure the resistance of liquid to flow. The measurement of viscosity is closely related to the fields of petroleum, chemical industry, electric power, metallurgy and national defense. It is an important means of industrial process control, improving product quality, saving and developing energy. In the fields of physical chemistry, fluid mechanics and other scientific fields, viscosity measurement plays an important role in understanding the properties of fluids and studying the flow state.

[0003] In the existing falling ball method, the small ball is introduced, which pollutes the liquid. Moreover, the small ball needs to be repeatedly measured and cleaned, which is not only troublesome but also time-consuming. Summary of the invention

[0004] The present invention is implemented through the following technical solutions. The characteristics of the drum method are that it introduces little pollution, is simple and convenient, and is easier to clean and quickly repeat the measurement than the small balls in the same type of falling ball method in previous patents. Therefore, this method is more simple and practical. In the invention, the bubbles are processed into small ball models, so the released bubbles are spherical bubbles as much as possible, which is conducive to the data processing of accurate measurement. In terms of operation, it can be repeated, and repeated operation is simple to operate. The bubble method requires that the viscosity of the liquid to be measured should not be too large, so that the bubbles stagnate and the bubbles and liquid do not dissolve each other.

[0005] The present invention is achieved through the following technical solutions.

[0006] A method for measuring liquid viscosity by a bubble method, characterized in that: when the liquid is stationary, a bubble ball is generated at the bottom of the liquid by a bubble generating device, and the bubble ball floats up under the action of the buoyancy of the liquid; and the floating time t and floating distance h of the bubble ball are measured at the same time;

[0007] During the measurement, according to Stokes' law, the bubble in the liquid is subjected to the viscous force f 粘 :

[0008] f 粘 =6πη 液 r 泡 v 泡 (1)

[0009] Where r is the bubble radius and ηliquid is the kinematic viscosity of the liquid.

[0010] The buoyancy force F exerted by the liquid on the bubble 浮 ,

[0011] F浮 =ρgV 泡 (2)

[0012] Among them, ρliquid is the density of the liquid, Vbubble is the volume of the bubble, and g is the gravitational acceleration.

[0013] The bubble's own gravity Gbubble can also be ignored if a low-density gas is used, which has a very small density relative to the liquid. This greatly facilitates the estimation of viscosity.

[0014] G 泡 =mg=ρ 泡 V 泡 g (3)

[0015] Calculation of viscosity coefficient by float method,

[0016] According to the force relationship satisfied when the ball reaches a state of equilibrium,

[0017] ρgV 排 -G=6πηrv(4)

[0018] The advantage of using the bubble method is that the density of air is very small compared to the density of liquid.

[0019] ρgV 排 ≈6πηrv(5)

[0020] The viscosity coefficient of the fluid can be calculated from the force relationship

[0021]

[0022] Ignoring the bubble's own weight

[0023]

[0024] The volume of the bubble ball Substituting it into the above formula, we can get

[0025]

[0026] Among them, ρ 液 is the density of the liquid being measured, g is the gravity constant, r is the radius of the bubble ball, and v is the floating speed of the bubble. 液 , g and r are constant properties, and only v is the definite quantity to be measured.

[0027] The measurement of V can be determined by the movement time and distance of the bubble ball.

[0028]

[0029] Substituting the speed into the viscosity coefficient formula, the relationship between the viscosity coefficient and the measured value can be obtained as follows:

[0030]

[0031] The method for measuring liquid viscosity according to claim 1, characterized in that the dynamic viscosity of the liquid is obtained according to the kinematic viscosity of the liquid.

[0032] μ 液 =η 液 ×ρ 液 (11).

[0033] Compared with the prior art, the advantages of the present invention are: compared with the falling ball method and the liquid drop method, the bubble method introduces less pollution, is simple and convenient, and is easier to clean and quickly repeat the measurement than the small balls in the same type of falling ball method in previous patents. Therefore, this method is more simple and practical. In the invention, the bubbles are processed into small ball models, so the released bubbles are as spherical as possible, which is conducive to the data processing of accurate measurement. In terms of operation, it can be repeated, and repeated operation is simple to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the initial position and measurement of the bubble of the present invention.

[0035] In the figure: 1. container, 2. liquid to be tested, 3. bubble ball. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0037] like Figure 1 As shown, a method for measuring liquid viscosity by a bubble method is characterized in that: when the liquid is stationary, a bubble ball is generated at the bottom of the liquid by a bubble generating device, and the bubble ball floats up under the action of the buoyancy of the liquid; and at the same time, the floating time t and the floating distance h of the bubble ball are measured;

[0038] During the measurement, according to Stokes' law, the bubble in the liquid is subjected to the viscous force f 粘 :

[0039] f 粘 =6πη 液 r 泡 v 泡

[0040] Where r is the bubble radius, ηliquid is the kinematic viscosity of the liquid,

[0041] The buoyancy force F exerted by the liquid on the bubble 浮 ,

[0042] F 浮 =ρgV 泡

[0043] Among them, ρliquid is the density of the liquid, Vbubble is the volume of the bubble, and g is the gravitational acceleration.

[0044] The bubble's own gravity Gbubble, if a low-density gas is used, is extremely small relative to the liquid density and can also be ignored, which greatly facilitates the viscosity estimation. Low-density gas, with a density lighter than air as a reference, that is, a density lower than the air density of 1.29kg / m 3 Preferred gases include helium and nitrogen.

[0045] G 泡 =mg=ρ 泡 V 泡 g

[0046] Calculation of viscosity coefficient by float method,

[0047] According to the force relationship satisfied when the ball reaches a state of equilibrium,

[0048] ρgV 排 -G=6πηrv

[0049] The advantage of using the bubble method is that the density of air is very small compared to the density of liquid.

[0050] ρgV 排 ≈6πηrv

[0051] The viscosity coefficient of the fluid can be calculated from the force relationship

[0052]

[0053] Ignoring the bubble's own weight

[0054]

[0055] Where ρball is the density of the bubble ball. The density value is 1.29kg / m 3 For bubble balls with a radius of 1 mm to 5 mm, it is estimated based on the ball model: The volume is about 4.187×10 -9 ~104.667×10 -9 m 3 , the weight of the bubble ball is about 5.401×10 -9 ~135.02×10 -9 kg. Taking water as an example, its density is 1.0×10 3kg, the drainage volume is the volume of the small ball, so the comparison between the drainage mass of the small ball and the mass of the bubble in the small ball is an order of magnitude difference in density, which is about 1000 times, which is equivalent to the three decimal places and can be approximately ignored.

[0056]

[0057] If there is a liquid with a smaller density than air to measure the viscosity, the bubble sinking method can be used instead for measurement. The bubble method is also applicable, but there is currently no public report on such liquids in reality.

[0058] The volume of the bubble ball Substituting it into the above formula, we can get

[0059]

[0060] Among them, ρ 液 is the density of the liquid being measured, g is the gravity constant, r is the radius of the bubble ball, and v is the floating speed of the bubble. 液 , g and r are constant properties, and only v is the definite quantity to be measured.

[0061] The measurement of V can be determined by the movement time and distance of the bubble ball.

[0062]

[0063] Substituting the speed into the viscosity coefficient formula (*), the relationship between the viscosity coefficient and the measured value can be obtained as follows.

[0064]

[0065] The method for measuring liquid viscosity according to claim 1, characterized in that the dynamic viscosity of the liquid is obtained according to the kinematic viscosity of the liquid.

[0066] μ 液 =η 液 ×ρ 液 .

[0067] The bubble generating device is a specially designed device. Addition, such as a bubble blowing method, generates bubbles.

[0068] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring liquid viscosity by a bubble method, characterized in that: When the liquid is at rest, a bubble ball is generated at the bottom of the liquid through a bubble generating device. The bubble ball floats up under the action of the buoyancy of the liquid. At the same time, the floating time t and floating distance h of the bubble ball are measured. During the measurement, according to Stokes' law, the bubble in the liquid is subjected to the viscous force f 粘 : f 粘 =6πη 液 r 泡 v 泡 (1) Where r is the bubble radius, ηliquid is the kinematic viscosity of the liquid; The buoyancy force F exerted by the liquid on the bubble 浮 , F 浮 =ρgV 泡 (2) Among them, ρliquid is the density of the liquid, Vbubble is the volume of the bubble, and g is the gravitational acceleration; The bubble's own gravity Gbubble, in the case of low-density gas, is extremely small relative to the liquid density and can be ignored; G 泡 =mg=ρ 泡 V 泡 g (3) Calculation of viscosity coefficient by float method, According to the force relationship satisfied when the ball reaches a state of equilibrium, ρgV 排 -G=6πηrv (4) The density of air is very small relative to the density of liquid; ρgV 排 ≈6πηrv(5)The viscosity coefficient of the fluid can be calculated from the force relationship, Neglecting the deadweight of the bubbles, The volume of the bubble ball Substituting it into the above formula, we can get Among them, ρ 液 is the density of the liquid being measured, g is the gravity constant, r is the radius of the bubble ball, and v is the floating speed of the bubble; And 液 , g and r are constant properties, only v is the determined quantity to be measured; The measurement of V can be determined by the movement time and distance of the bubble ball. Substituting the speed into the viscosity coefficient formula, the relationship between the viscosity coefficient and the measured value can be obtained as follows: According to the kinematic viscosity of the liquid, the dynamic viscosity of the liquid is obtained. m 液 =the 液 ×r 液 (11)。

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