How is kinematic viscosity tested? Kinematic viscosity calculation formula

At a constant temperature, a certain volume of specimen is determined to flow through a calibrated sample under gravity.

The time of the glass capillary viscometer, the product of the capillary viscometer constant and the flow time, is that.

Determination of the kinematic viscosity of liquids at temperature.

For specifying the same capillary viscometer, the capillary constant c is a constant (attached to the Pinch viscometer strip).

Then the kinematic viscosity is calculated as follows:

=ηdv/dx=ηd。

The kinematic viscosity is the ratio of the dynamic viscosity of a fluid to the density of the fluid at the same temperature. The unit is (m2) s. It is denoted by the lowercase letter v.

Viscosity Determination Method:

1. Dynamic viscosity: t is the resistance generated when the two liquid layers are 1 cm apart from each other, and their areas are 1 relative to the moving speed of 1 cm second, and the unit is gramm·s. 1 gram centimeter·second = 1 poise, the unit of dynamic viscosity in general industry is expressed in poise.

2. Kinematic viscosity: when the temperature t is disturbed, the kinematic viscosity is expressed by symbols, in the International System of Units, the viscosity unit of the kinematic front is Si, that is, square meters per second, and the actual measurement is commonly used in cents, which means that the unit of centimeters is millimeters square per second. The kinematic viscosity is widely used to determine the viscosity of liquid petroleum products such as jet fuel oil, diesel oil, lubricating oil, dark petroleum products, lubricating oil after use, etc., and the determination of kinematic viscosity adopts the countercurrent method.

3. Conditional viscosity: refers to the viscosity expressed in conditional units measured by different specific viscometers, which is widely used for the determination of liquid stone-based oil products such as jet fuel oil, diesel oil, and lubricating oil. <>

Formula for calculating the dynamic viscosity of Yunhu Deficiency: (Dynamic viscosity.

dv/dx=ηd。Dynamic viscosity, also known as dynamic viscosity, absolute viscosity or simple viscosity, is defined as the ratio of stress to strain rate, which is numerically equal to the internal friction force generated by the interaction of fluids between two plates with an area of 1 m apart and 1 m apart when they move relative to each other at a speed of 1 m s.

Viscosity is a physical chemical property of a substance.

Defined as a pair of parallel plates with an area of A, separated by DR, and filled with a certain liquid between the plates; Now apply a thrust f to the upper plate so that it produces the force required by a degree of velocity variation. Due to the action of viscosity, the object is subjected to frictional resistance and differential pressure resistance when moving in the fluid, resulting in mechanical energy.

(see Flow Resistance).

The correct way to write kinematic viscosity is kinematic viscosity, and kinematic viscosity is fluidDynamic viscosityThe ratio of the density of the fluid at the same temperature. The unit is (m2) s, which is denoted by the lowercase letter v.

Note: The units used to be used are st(s), cst(rees) and (m2) s, and the relationship between the advance rate is: 1(m2) s=10 4st=10 6cst.

where "CST" is pronounced as "centicent"), the liquid flowing is seen as many layers moving parallel to each other, and the velocity of each layer is different, forming a velocity gradient (dv dx), which is the basic characteristic of flow.

Viscosity determination:

There are three methods for determining dynamic viscosity, kinematic viscosity and conditional viscosity.

1) Dynamic viscosity: t is the resistance generated when two liquid layers are 1 cm apart from each other, and their areas are 1 (square centimeters) and their relative moving speed is 1 cm second, and the unit is Crimi ·s. 1 gram cm·s = 1 poise general:

In industry, the unit of dynamic viscosity is expressed in terms of poise.

2) Kinematic viscosity: At the temperature t, the kinematic viscosity is expressed by a symbol, in the International System of Units.

, the unit of kinematic viscosity is s, that is, square meters per second (m2 s), and in actual measurement, centis, (cst) is commonly used in the unit of centicents square millimeters per second.

i.e. 1cst=1mm2 s).

3) Conditional viscosity: refers to the viscosity expressed in conditional units measured by different specific viscometers.

Wuhan Huatian Electric Power specializes in the production of kinematic viscometer (also known as automatic kinematic viscosity tester), and the following is an introduction to the kinematic viscosity formula.

Kinematic viscosity is a measure of the inherent resistance of a fluid to flow without applying an external force (other than gravity). It is the ratio of dynamic viscosity to its density and is independent of force. Kinematic viscosity can be obtained by dividing the absolute viscosity of the fluid by the mass density of the fluid.

Kinematic viscosity = dynamic viscosity Fluid limb ulnar mass density. The equation is written.

We have :: kinematic viscosity.

Fluid density. Dynamic viscosity.

Kinematic viscosity formula problem: high content.

1) What is the kinematic viscosity of mercury weighing 2 kg per liter?

Answer: The dynamic viscosity of mercury is = Pa * S. First, calculate the density mass of mercury using the formula = mass volume.

2 kg 1 liter = 2 kg m3 = 2000 kg m3

The kinematic viscosity is then calculated using its formula.

pa * s / 2000 kg / m 3 =（ n * s / m 2）/（2000 kg / m 3）

m 2 seconds.

2) What is the density of a fluid with a kinematic viscosity of 1 m2 s and a dynamic viscosity of Pa*s?

Answer: According to the kinematic viscosity formula, we can find the density, = and then substitute the value, = ( n * s m 2) (1 m 2 s) = kg m 3

Respondent: Huatian Power.

The kinematic viscosity is calculated by the following formula: (dynamic viscosity width positive) = dv dx = d. Dynamic viscosity, also known as dynamic viscosity, absolute viscosity or simple viscosity, is defined as the ratio of stress to strain rate, which is numerically equal to the internal friction caused by the interaction of fluids between two Qiqing plates with an area of 1 m apart and a distance of 1 m between them when they move relative to each other at a speed of 1 m s.

The "kinematic viscosity tester" is suitable for determining the kinematic viscosity of liquid petroleum products. This method is suitable for the determination of kinematic viscosity of liquid petroleum products. Kinematic viscosity is a measure of the internal friction of a liquid as it flows under gravity, and its value is the ratio of the dynamic viscosity to its density at the same temperature.

It is one of the important physical and chemical performance indicators for the identification of oil grade and quality. In practical applications, choosing the right viscosity of lubricating oil can ensure the normal and reliable operation of machinery and equipment. We take the widely used "A1010 kinematic viscosity tester" on the market as an example, and pay attention to the following aspects when buying a "kinematic viscosity tester":

1.It is composed of computer temperature control, timing, constant temperature, water bath and other parts. The thermostatic bath is a small cylinder, a round cylinder, a double layer, and the temperature distribution in the bath is uniform, and the temperature control effect is excellent.

2.LCD screen Chinese display, man-machine dialogue interface, preset temperature, test time and other parameters, menu prompt input, actuator adopts advanced SSR, its characteristics no contact, no action noise, no sparks, vibration resistance, long life.

3.The inner parts of the bath, such as the heater and the deflector cylinder, are made of stainless steel, which is corrosion-resistant and durable.

4.Ring fluorescent lighting, easy to observe.

5.Automatically calculates the product of the capillary constant and the mean value of the test time; The temperature control accuracy is high and the accuracy is good.

Pay attention to the above points, you can buy a satisfactory "kinematic viscosity tester".

The ratio of the dynamic viscosity of a fluid to the density of that fluid at the same temperature.

The unit is (m2) s. It is denoted by the lowercase letter v. Note:

The units used to be used are st(s), cst (reese) and (m2) s, and the relationship between the rate of progress is: 1 (m 2) s=10 4st = 10 6cst. where "CST" is pronounced as "centicent"), the liquid flowing is seen as many layers moving parallel to each other, and the velocity of each layer is different, forming a velocity gradient (dv dx), which is the basic characteristic of flow.

This force exerted per unit of liquid layer area is known as shear stress (n m2).

Shear rate (d) d=d v d x (s-1).

Shear stress and shear rate are the two basic parameters that characterize the rheological properties of a system.

Newton defined the viscosity of a fluid in the pattern of Figure 4-1. Two fluids of different planes but parallel have the same area "a", are separated by a distance of "dx", and flow in the same direction at different flow rates "v1" and "v2";

Newtonian postulated that the force that keeps this different flow velocity proportional to the relative velocity or velocity gradient of the fluid, i.e.: = dv dx = d (Newton's formula) where related to the properties of the material, we call it "dynamic viscosity".

Definition of dynamic viscosity: two plates with an area of 1m2 are immersed in a liquid, and the distance between the two plates is 1 m, if a shear stress of 1n is added to make the relative rate between the two plates 1 m s, then the viscosity of this liquid is.

Newtonian fluids: Fluids that conform to Newton's formula. Viscosity is only related to temperature, not to shear rate, and is directly proportional to d.

Non-Newtonian fluid: does not conform to Newton's formula d=f(d), and a represents the viscosity under a certain (d), which is called apparent viscosity.

Viscosity tensor. In general, the stress in the flow can be partly due to the deformation of the material from the resting state (elastic stress) and partly to the rate of change of the deformation over time (viscous stress). In fluids, elastic stress includes, by definition, only hydrostatic pressure.

In general terms, the viscosity of a fluid is the relationship between the strain rate and the viscous stress.

In the Newtonian fluid model, the relationship is given by defining a linear map, described by the viscosity tensor, multiplied by the strain rate tensor (which is the velocity gradient of the flow).

In general, viscosity tensors have nine independent degrees of freedom. Isotropic Newtonian fluids, which can be reduced to two independent parameters. The most common are stress viscosity and bulk viscosity.