Oil viscosity detection device

Abstract

The utility model relates to the technical field of oil liquid detection, and discloses an oil liquid viscosity detection device which comprises an oil supply mechanism and a testing mechanism, the oil supply mechanism comprises an oil storage tank and an oil pump, the testing mechanism comprises a testing box, an oil outlet pipe, an oil receiving disc, a flow meter and a liquid level adjusting assembly, and the oil storage tank is communicated with the testing box through the oil pump; the liquid level adjusting assembly is used for controlling the height of the liquid level in the testing box, the oil outlet pipe is horizontally arranged, one end of the oil outlet pipe is connected to the position close to the bottom of the testing box and communicated with the testing box, the other end of the oil outlet pipe is located above the oil receiving disc, one end of the flow meter is communicated with the oil receiving disc, and the other end of the flow meter is located above the oil receiving disc. And the other end of the flow meter is communicated with the oil storage tank. According to the invention, the convenience of oil viscosity detection can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil detection, and particularly to an oil viscosity detection device. BACKGROUND

[0002] Lubricating oil, hydraulic oil and fuel oil and other types of oil are widely used in engineering machinery, transportation, metallurgy, manufacturing, petrochemical industry and power industry, and are important commodities related to national economy and people's livelihood. The density and viscosity characteristics of oil are important physical and chemical indexes in industrial production, so how to detect the density and viscosity of these oils in real time in process control is crucial.

[0003] At present, the density and viscosity of lubricating oil are mostly detected by large experimental instruments, such as automatic viscosity tester, densimeter and other measuring instruments. These instruments are generally expensive, bulky, complex to operate, and require a very stable operating environment, such as a laboratory.

[0004] However, the flow rate of the oil in the field, the representativeness of the oil sample, and the temperature of the oil product are all different from those in the laboratory, and the data measured by these instruments have a large gap with the working conditions of the oil in the field. The manual periodic oil taking operation not only brings experimental errors, but also cannot monitor the running condition of the oil in real time, and lacks timeliness in judging sudden accidents.

[0005] In addition, the existing oil quality detection device cannot measure the density and viscosity at the same time, and lacks some measurement indexes. In theory, multiple sensors can be installed to measure the density and viscosity at the same time, but multiple sensors not only increase the production cost, but also are not conducive to the integration of the system. CONTENT OF THE INVENTION

[0006] In order to alleviate the above technical problems, the present application provides an oil viscosity detection device.

[0007] The oil viscosity detection device provided by the present application adopts the following technical scheme:

[0008] An oil viscosity detection device, comprising an oil supply mechanism and a test mechanism, the oil supply mechanism comprising an oil storage tank and an oil pump, the test mechanism comprising a test tank, an oil outlet pipe, an oil receiving disc, a flow meter and a liquid level adjusting assembly, the oil storage tank being communicated with the test tank through the oil pump, the liquid level adjusting assembly being used to control the liquid level in the test tank, the oil outlet pipe being horizontally arranged, one end of the oil outlet pipe being connected to a position close to the bottom of the test tank and the oil outlet pipe being communicated with the test tank, the other end of the oil outlet pipe being located above the oil receiving disc, one end of the flow meter being communicated with the oil receiving disc, the other end of the flow meter being communicated with the oil storage tank.

[0009] By adopting the technical scheme, the oil tank is communicated with the test tank through the oil pump, the oil in the test tank flows into the oil receiving disc through the oil outlet pipe, the oil level adjusting assembly is used to adjust the oil level in the test tank, thereby changing the oil flow rate in the oil outlet pipe, according to

[0010]

[0011] In the formula, Q 理 is the calculated orifice flow, with the unit of ml / min; C d is the flow coefficient, dimensionless; A0 is the orifice flow area, with the unit of mm 2 ; ρ is the fluid density, with the unit of kg / m 3 ; d is the orifice diameter, with the unit of mm; ΔP is the pressure difference at both ends of the orifice, with the unit of Pa; g is the gravitational acceleration, which can be taken as 9.8 m 2 / s; h is the height from the oil liquid surface in the test tank to the center of the orifice, with the unit of mm; the critical tearing speed V c of the oil liquid in the oil outlet pipe is calculated, the measured flow Q 实 of the flowmeter is compared with Q 理 , in the case that the measured flow Q 实 is close to the theoretical flow Q 理 , the oil amount pumped into the test tank by the oil pump is controlled; when the orifice outlet distance is retracted backward, the measured flow Q 实 should be substantially equal to the theoretical flow Q 理 , in the case that the two conditions are met, the liquid surface height h in the test tank is recorded and kept; in the case that the liquid surface height h is stable, Q 实 is measured three times, the average value Q 平 is calculated, the orifice flow area A0 is calculated according to the orifice diameter d, and then the critical tearing speed V c = Q 平 / A0 can be obtained.

[0012] By defining H to represent the characteristic parameter for ensuring continuous flow of the fluid, r a v c represents the size thereof, v c xr a represents the direction of the motion of the viscous rotational direction, and a dimensionless coefficient k is further introduced, so that the kinematic viscosity γ = μ / ρ = kH can be obtained, and the kinematic viscosity is connected with the characteristic parameter H representing the continuous flow of the fluid, that is.

[0013] Therefore, the Reynolds number R e = ρvd / μ can also be expressed as:

[0014]

[0015] where v is the flow velocity in the orifice, d is the diameter of the orifice, μ is the dynamic viscosity, ρ is the fluid density, H is a characteristic parameter for ensuring continuous flow of the fluid, H = γ / k, with the same unit as the kinematic viscosity γ, k is a dimensionless coefficient, r a is the gasification distance after the tear of the molecular group, and v c is the critical tear velocity.

[0016] According to the typical curve of the relationship between the orifice flow coefficient and the Reynolds number, when the flow velocity v = v c , assuming that the rigid small ball structure between the fluid molecules still maintains the close arrangement, then the average distance between the molecules in the orifice reaches the tear (gasification) distance r a , but because the fluid is in a three-dimensional space, only one dimension r a ≈10r0 in the flow direction, due to the approximate incompressibility of the fluid, the molecular distance in other directions basically remains no more than r0, the density ρ up ≈ρ at the front end of the orifice, so the fluid density in the orifice decreases by about 10 times, ρ down ≈ρ / 10; therefore, the pressure difference potential energy ΔP not only ensures that the flow velocity v = v c in the orifice, but also, with the spatial restriction of the pipe wall, ensures that the molecular arrangement density ρ in the non-flow direction does not change, and the energy of the two parts of the density difference and the flow is equal under the equalization of the molecular thermal motion, i.e. Thus, the flow coefficient C d =sqrt(1 / 2)=0.707, which is almost equal to the extreme value 0.7 of the orifice flow coefficient in the typical curve of the relationship between the orifice flow coefficient and the Reynolds number, so it is considered that C d =sqrt(1 / 2)=0.707 corresponds to the critical Reynolds number R e =100, and the critical Reynolds number in the middle part of the orifice is:

[0017]

[0018] where ρ down is the fluid density in the orifice after the fluid density decreases to the cavitation flow due to the flow, v is the flow velocity in the orifice, d is the diameter of the orifice, μ is the dynamic viscosity, ρ is the fluid density, H is a characteristic parameter for ensuring continuous flow of the fluid, H = γ / k, with the same unit as the kinematic viscosity γ, k is a dimensionless coefficient, r a is the gasification distance after the tear of the molecular group, and v c is the critical tear velocity.

[0019] Thus, we have:

[0020]

[0021] Substitute the calculation formula of Reynolds number at normal temperature and pressure, and simplify to obtain

[0022]

[0023] Extract the dynamic viscosity mu to obtain

[0024] Introducing the unit of dynamic viscosity pa.s and the unit of orifice diameter mm, the conversion can be obtained

[0025]

[0026] In the formula, mu is the dynamic viscosity, the unit is pa.s; rho is the fluid density, the unit is kg / m 3 ; d is the orifice diameter, the unit is mm; v c is the critical tearing speed, the unit is m / s;

[0027] Further, the kinematic viscosity gamma = mu / rho can be obtained

[0028] Introducing the unit of kinematic viscosity (m^2) / s and the unit of orifice diameter mm, the conversion can be obtained

[0029]

[0030] In the formula, gamma is the kinematic viscosity, the unit is (m^2) / s; d is the orifice diameter, the unit is mm; v c is the critical tearing speed, the unit is m / s; the calculation is convenient.

[0031] Optionally, the liquid level adjusting assembly comprises a plurality of drainage tubes in communication with the test tank, the plurality of drainage tubes are arranged at intervals along the height direction of the test tank, the other end of the drainage tube is in communication with the oil storage tank, a switch valve for controlling the on-off of the drainage tube is arranged on the drainage tube, a liquid level sensor is arranged in the test tank, and the oil pump is electrically connected with a controller.

[0032] By adopting the above technical scheme, a plurality of drainage tubes are arranged at intervals along the height direction of the test tank, and a switch valve is correspondingly arranged on each drainage tube, the height of the oil in the test tank is adjusted by opening the corresponding switch valve and adjusting the flow of the oil pump, and the liquid level height in the test tank is adjusted conveniently.

[0033] Optionally, the oil outlet pipe is made of transparent material, and the test mechanism further comprises a laser particle detection device for testing the oil particles at the positions of both ends of the oil outlet pipe.

[0034] By adopting the technical scheme, the liquid level in the test tank is controlled from low to high, when the laser particle detection equipment finds that the particles increase, and the outflow speed is less than the maximum outflow speed, at this time, the liquid level in the stable large oil tank is stabilized, the maximum flow is measured through the flow meter, the measured maximum flow Q is substituted into The calculated flow, if the error of both ends of the formula is less than 5%, then through Q / A0=V c , the critical tearing speed V c is calculated. BRIEF DESCRIPTION OF DRAWINGS

[0035] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0036] Figure 1 is a schematic diagram of the overall structure of the embodiment of the present application;

[0037] Figure 2 is a typical curve of the relationship between the flow coefficient of the oil outlet pipe and the Reynolds number in the embodiment of the present application.

[0038] Figures: 100, oil supply mechanism; 110, oil storage tank; 120, oil pump; 200, test mechanism; 210, test tank; 220, oil outlet pipe; 230, oil receiving disc; 240, flow meter; 250, liquid level adjusting assembly; 251, drainage pipe; 252, on-off valve; 253, controller; 254, liquid level sensor. DETAILED DESCRIPTION

[0039] In order to more clearly explain the overall concept of the present application, the following will be combined with the drawings to further specifically explain the present application. Figures 1-2 The present application is further described in detail.

[0040] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below. It should be noted that the embodiments of the present application and the features in each embodiment can be combined with each other without conflict.

[0041] The embodiment of the present application discloses an oil viscosity detection device. Referring to Figure 1The oil viscosity detection device comprises an oil supply mechanism 100 and a test mechanism 200. The oil supply mechanism 100 comprises an oil tank 110 and an oil pump 120. The test mechanism 200 comprises a test tank 210, an oil outlet pipe 220, an oil receiving disc 230, a flow meter 240 and a liquid level adjusting assembly 250. The oil tank 110 is communicated with the test tank 210 through the oil pump 120. The liquid level adjusting assembly 250 is used for controlling the liquid level in the test tank 210. The oil outlet pipe 220 is horizontally arranged. One end of the oil outlet pipe 220 is connected to a position close to the bottom of the test tank 210 and the oil outlet pipe 220 is communicated with the test tank 210. The other end of the oil outlet pipe 220 is located above the oil receiving disc 230. One end of the flow meter 240 is communicated with the oil receiving disc 230. The other end of the flow meter 240 is communicated with the oil tank 110.

[0042] The liquid level adjusting assembly 250 comprises a plurality of drainage pipes 251 communicated with the test tank 210. The plurality of drainage pipes 251 are arranged at intervals along the height direction of the test tank 210. The other end of the drainage pipe 251 is communicated with the oil tank 110. A switch valve 252 for controlling the opening and closing of the drainage pipe 251 is arranged on the drainage pipe 251. A liquid level sensor 254 is arranged in the test tank 210. The oil pump 120 is electrically connected with a controller 253. The controller 253 is used for controlling the flow rate of the oil in the oil pump 120. The controller 253 is electrically connected with the liquid level sensor 254.

[0043] In other preferable embodiments, the oil outlet pipe 220 is made of transparent material. The test mechanism 200 further comprises a laser particle detection device for testing the oil particles at the two ends of the oil outlet pipe 220.

[0044] The application further discloses an oil viscosity detection method. The detection method adopts the detection device and mainly comprises the following steps.

[0045] S1, according to

[0046]

[0047] In the formula, Q 理 is the calculated orifice flow, with the unit of ml / min; C d is the flow coefficient, with no dimension; A0 is the orifice flow area, with the unit of mm 2 ; ρ is the fluid density, with the unit of kg / m 3 ; d is the orifice diameter, with the unit of mm; ΔP is the pressure difference at the two ends of the orifice, with the unit of Pa; g is the gravity acceleration, which can be taken as 9.8 m 2 / s; and h is the height of the oil liquid surface in the test tank to the center of the orifice, with the unit of mm.

[0048] The critical tearing speed V c, the liquid level in the test tank is adjusted from low to high by the liquid level adjusting assembly, the actual flow rate Q 实 of the flowmeter is measured, and the flow rate Q 理 of the flowmeter is compared with the theoretical flow rate Q 实 , the oil pump is controlled to pump oil into the test tank when the actual flow rate Q 理 is close to the theoretical flow rate Q 实 , the actual flow rate Q 理 is substantially equal to the theoretical flow rate Q 实 , the liquid level h in the test tank is recorded and kept constant, the actual flow rate Q 平 is measured three times, the average value Q c is calculated, the orifice flow area A0 is calculated according to the orifice diameter d, and the critical tearing speed V 平 = Q a / A0 is obtained.

[0049] S2, the dynamic viscosity μ is calculated, the characteristic parameter H representing the continuous flow of fluid is defined, and the size of the characteristic parameter H is represented by r c v c , the direction of the viscous rotational shear of the motion is represented by v a × r e , and a dimensionless coefficient k is introduced, so that the kinematic viscosity γ = μ / ρ = kH is obtained, and the kinematic viscosity is related to the characteristic parameter H representing the continuous flow of fluid.

[0050] Therefore, the Reynolds number R a = ρvd / μ can be expressed as:

[0051]

[0052] In the formula, v is the flow rate in the orifice, d is the diameter of the orifice, μ is the dynamic viscosity, ρ is the density of the fluid, H is the characteristic parameter representing the continuous flow of fluid, H = γ / k, the unit of the kinematic viscosity γ is the same as that of the characteristic parameter H, k is a dimensionless coefficient, r c is the gasification distance after tearing of the molecular group, and v c is the critical tearing speed.

[0053] According to the typical curve of the relationship between the flow coefficient of the orifice and the Reynolds number, when the flow rate v = v a , it is assumed that the fluid molecules still maintain the rigid ball structure with close arrangement, the average distance between the molecules in the orifice reaches the tearing (gasification) distance r a , but in the three-dimensional space of the fluid, only one dimension r up ≈ 10r0 in the flow direction, due to the approximate incompressibility of the fluid, the average distance of the molecular motion in other directions remains substantially not greater than r0, and the density ρ≈p, so, the fluid density in the orifice drops about 10 times, p down ≈p / 10; therefore, the pressure difference potential energy ΔP not only ensures the flow velocity v=v c in the orifice, but also, with the help of the spatial restriction of the pipe wall, ensures the molecular arrangement density p in the non-flow direction unchanged, and maintains the energy of the two parts of the density difference and the flow under the equalization of the molecular thermal motion, i.e. Thus, the flow coefficient C d =sqrt(1 / 2)=0.707, which is almost equal to the extreme value 0.7 of the typical curve of the orifice flow coefficient and Reynolds number relationship, so it is considered that C d =sqrt(1 / 2)=0.707 corresponds to the critical Reynolds number R e =100, then the critical Reynolds number in the middle of the orifice is:

[0054]

[0055] In the formula, p down is the fluid density in the orifice after the fluid density drops to the cavitation flow due to flow, v is the flow velocity of the liquid in the orifice; d is the diameter of the orifice; μ is the dynamic viscosity; p is the fluid density; H represents a characteristic parameter for ensuring continuous flow of the fluid, H=γ / k, the unit is the same as the kinematic viscosity γ; k is a dimensionless coefficient; r a is the gasification distance after the molecular group is torn apart; v c is the critical tearing speed;

[0056] Then:

[0057]

[0058] Substitute the calculation formula of the Reynolds number at normal temperature and pressure, and simplify to obtain

[0059]

[0060] Extract the dynamic viscosity μ to obtain

[0061] Introduce the dynamic viscosity unit pa.s and the orifice diameter unit mm, and convert to obtain

[0062]

[0063] In the formula, μ is the dynamic viscosity, the unit is pa.s; p is the fluid density, the unit is kg / m 3 ; d is the diameter of the orifice, the unit is mm; v c is the critical tearing speed, the unit is m / s;

[0064] Further, the kinematic viscosity γ = μ / ρ can be obtained

[0065] The kinematic viscosity unit (m2) / s and the throttle hole diameter unit mm are introduced, and the conversion can be obtained

[0066]

[0067] In the formula, γ is the kinematic viscosity, unit (m2) / s; d is the throttle hole diameter, unit mm; v c is the critical tearing speed, unit m / s;

[0068] According to the Bernoulli equation, the throttle hole flow calculation formula is derived, In the formula, Q represents the flow, unit m3 / s; C d is the flow coefficient, dimensionless; A0 is the flow area of the throttle hole, A0 = π / 4 * d 2 , unit m2; ρ is the density of the fluid, unit Kg / m 3 ; ΔP is the pressure difference before and after the throttle hole, unit Pa.

[0069] The flow revision coefficient C d is less than 100%, then if the flow coefficient C d is moved into The square root, it can be seen that the pressure potential contained in the pressure difference ΔP in the square root is not all converted into kinetic energy of fluid flow. If it is one-dimensional pipe flow, under the condition that the flow area A0 is constant, the pressure difference potential between the throttle holes is converted into fluid flow, and the other part is still acting on the normal direction of the pipe wall through the continuous heat motion, which indirectly provides support for the flow direction of the fluid (if there is no such pressure difference support to ensure flow, one is a static communication device, the fluid no longer flows, and the pressure difference at both ends is 0; another is to flow in an open one-dimensional flow pipe, such as a river, the pressure head difference at both ends directly acts on the flow of the fluid, thereby forming a Figure 2 The parabolic shape before the flow coefficient is 0.7, which increases with the increase of pressure or flow rate, and does not need the pressure difference between the throttle hole walls to gather pressure. The two parts of energy are essentially the heat motion of fluid molecules, so under the average action of heat motion, the energy of the two parts should be uniform, that is, each occupies half of the pressure difference potential ΔP between the throttle holes (half for maintaining the pressure head of the flow, and half for the flow of the fluid). Therefore, according to The flow coefficient of the throttle hole will not exceed 1 / 2 of the square root, that is, 0.707, and this conclusion is also consistent with Figure 2 The typical curve of the relationship between the flow and the Reynolds number of the throttle hole flow coefficient C d, the typical experimental value of 0.7 is quite close to the maximum value, which shows that this method of calculating the flow coefficient by energy balance is reliable.

[0070] For Figure 2 The typical curve of the relationship between the flow coefficient C d After reaching 0.7, it decreases with the increase of flow rate, and then gradually stabilizes at about 0.6, which shows that in the one-dimensional pipeline turbulent flow (torn cavity flow), part of the pressure potential energy still needs to act on the normal direction of the pipe wall to provide support force in the direction of fluid flow. In addition, two parts of the pressure potential energy are converted into fluid flow kinetic energy and the oscillation energy generated by the continuous disappearance and generation of high-speed torn cavities. These three parts of energy are still balanced and consistent at the molecular thermal motion level. Therefore, according to the balance principle of the three parts of energy, the pressure potential energy used for fluid flow only accounts for 1 / 3 of the pressure potential energy ΔP between the throttling holes. Therefore, the flow coefficient

[0071] The above flow coefficient C d The theoretical derivation of the maximum value 0.7 and the stable value 0.6 is carried out, and this inference is in good agreement with the flow coefficient 0.7 and 0.6 obtained by experiment Figure 2 The flow coefficient C d The flow coefficient 0.7 and 0.6 reflected by the typical curve of the relationship between the flow coefficient and the Reynolds number are well fitted, so this further shows that our assumption of torn cavitation caused by too fast flow is more reliable.

[0072] Select the flow coefficient Cd = 0.707 in Figure 2 , and calculate the flow rate Q

[0073] For the critical tearing speed V c , the present application provides two calculation methods:

[0074] Method 1, according to

[0075]

[0076] In the formula, Q 理 is the calculated flow rate of the throttling hole, unit: ml / min; C d is the flow coefficient, dimensionless; A0 is the flow area of the throttling hole, unit: mm 2 ; ρ is the fluid density, unit: kg / m 3 ; d is the diameter of the throttling hole, unit: mm; ΔP is the pressure difference between the two ends of the throttling hole, unit: Pa; g is the acceleration of gravity, which can be taken as 9.8 m 2 / s; h is the height from the oil level in the test box to the center of the throttle hole, unit: mm;

[0077] Calculate the critical tearing velocity V of the oil in the oil outlet pipe c , adjust the liquid level in the test box from low to high through the liquid level adjustment component, and change the measured flow rate Q of the flow meter 实 With Q 理 For comparison, the measured flow rate Q 实 Close to theoretical flow rate Q 理 In the case of , control the oil pump to pump the oil into the test box; when the outflow distance of the throttle hole is retracted, the measured flow rate Q 实 Should be basically equal to the theoretical flow rate Q 理 When these two conditions are met, record and keep the liquid level h in the test box; when the liquid level h is stable, measure Q three times. 实 , calculate the average value Q 平 Then, the orifice flow area A0 is calculated based on the orifice diameter d, and the critical tearing velocity V is obtained. c =Q 平 / A0;

[0078] Method 2: Control the liquid level in the test box from low to high. When the laser particle detection equipment finds that the particles increase, and the outflow rate is less than the maximum outflow rate, stabilize the liquid level in the large oil tank, measure the maximum flow rate through the flow meter, and substitute the measured maximum flow rate Q into If the error between the two ends of the calculated flow rate is less than 5%, then Q / A0=V c , calculate the critical tearing velocity V c .

[0079] The kinematic viscosity coefficient γ is often used in fluid calculations. Its value is the ratio of the dynamic viscosity coefficient μ to its density ρ, that is, γ = μ / ρ, and its dimension is M. 2 / S, there is no special physics, just related to the viscous force and inertial force respectively, then, multiplying them together can get the characteristic parameter r that characterizes the continuous flow of the fluid a v c , whose dimension is also M 2 / S, and has a more obvious physical meaning, which is the product of the critical parameters before the fluid cavitation, that is, the critical tearing speed v must be reached at the same time c and tearing (gasification) distance r a The fluid may experience cavitation with discontinuous streamlines, which is a parameter used to characterize the difference between laminar flow and turbulent flow. Let this characterization parameter r a v c =H, used to characterize the maximum adhesion characteristics of critical cavitation of flowing liquid. Define H to characterize the characteristic parameter that ensures continuous flow of fluid. a vc Indicate its size, use v c ×r a The direction of the movement represents the viscous shear direction, and further introducing a dimensionless coefficient k, we can get the kinematic viscosity γ = μ / ρ = kH, and we can get that the kinematic viscosity is related to the characteristic parameter H that characterizes the continuous flow of the fluid.

[0080] Therefore, the Reynolds number R e =ρvd / μ can also be expressed as:

[0081]

[0082] Where v is the flow velocity in the orifice; d is the orifice diameter; μ is the dynamic viscosity; ρ is the fluid density; H represents the characteristic parameter that ensures the continuous flow of the fluid, H = γ / k, with the same unit as the kinematic viscosity γ; k is the dimensionless coefficient; r a v is the vaporization distance after the molecular cluster is torn; c is the critical tearing speed;

[0083] Reference Figure 2 According to the typical curve of the relationship between the orifice flow coefficient and the Reynolds number, when the flow velocity v=v c Assuming that the fluid molecules still maintain a dense rigid spherical structure, the average distance between the molecules in the throttle hole reaches the tearing (gasification) distance r a However, in the three-dimensional space of the fluid, only one dimension r in the flow direction is a ≈10r0. Due to the approximate incompressibility of the fluid, the molecular distance in other directions is basically kept no greater than r0. The density ρ at the front end of the throttle hole up ≈ρ, so the fluid density in the throttle hole drops by about 10 times, ρ down ≈ρ / 10; therefore, the pressure difference potential energy ΔP is not only used to ensure the flow velocity v=v in the throttle hole c Moreover, the spatial restriction of the tube wall is used to ensure that the molecular arrangement density ρ in the non-flow direction remains unchanged, and the energy of the two parts of the density difference and the flow is equal under the equilibrium effect of molecular thermal motion. Figure 2 ,Right now Thus, the flow coefficient C can be obtained d =sqrt(1 / 2)=0.707, which is almost equal to the extreme value of 0.7 of the typical curve of the relationship between the orifice flow coefficient and the Reynolds number, so it is believed that C d =sqrt(1 / 2)=0.707 corresponds to the critical Reynolds number R e =100, then the critical Reynolds number in the middle of the throttle hole is:

[0084]

[0085] In the formula, p down is the fluid density in the throttle hole after the fluid density drops due to flow to cavitation flow, v is the flow velocity in the throttle hole; d is the throttle hole diameter; μ is the dynamic viscosity; p is the fluid density; H represents a characteristic parameter for ensuring continuous flow of the fluid, H = γ / k, with the same unit as the dynamic viscosity γ; k is a dimensionless coefficient; r a is the gasification distance after the molecular group is torn apart; v c is the critical tearing speed;

[0086] Then:

[0087]

[0088] Substitute the calculation formula of the Reynolds number at normal temperature and pressure, and simplify to obtain

[0089]

[0090] Extract the dynamic viscosity μ to obtain

[0091] Introduce the dynamic viscosity unit pa.s and the throttle hole diameter unit mm, and convert to obtain

[0092]

[0093] In the formula, μ is the dynamic viscosity, with the unit pa.s; p is the fluid density, with the unit kg / m 3 ; d is the throttle hole diameter, with the unit mm; v c is the critical tearing speed, with the unit m / s;

[0094] Further, extract the dynamic viscosity γ = μ / p to obtain

[0095] Introduce the dynamic viscosity unit (m^2) / s and the throttle hole diameter unit mm, and convert to obtain

[0096]

[0097] In the formula, γ is the dynamic viscosity, with the unit (m^2) / s; d is the throttle hole diameter, with the unit mm; v c is the critical tearing speed, with the unit m / s;

[0098] The places not mentioned in the application can be realized by using or referring to the existing technology.

[0099] The above are preferred embodiments of the application, and do not limit the protection scope of the application, so: any equivalent changes made on the structure, shape, principle of the application should be covered within the protection scope of the application.

Claims

1. An oil viscosity detection device, characterized by: The oil supply mechanism comprises an oil storage tank and an oil pump, and the test mechanism comprises a test tank, an oil outlet pipe, an oil receiving disc, a flow meter and a liquid level adjusting assembly.

2. The oil viscosity detection device according to claim 1, characterized in that: The liquid level adjusting assembly comprises a plurality of drainage pipes in communication with the test tank, the drainage pipes are arranged at intervals along the height direction of the test tank, the other ends of the drainage pipes are in communication with the oil storage tank, and switch valves for controlling the opening and closing of the drainage pipes are arranged on the drainage pipes.

3. The oil viscosity detection device according to claim 2, characterized in that: The oil outlet pipe is made of transparent material, and the test mechanism further comprises a laser particle detection device for testing the oil particle at the two ends of the oil outlet pipe.

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