A centrifuge supergravity field pure pressure energy gradient permeation test device

Abstract

The application discloses a centrifuge supergravity field pure pressure energy gradient permeation test device, which comprises a permeation pressure chamber, a syringe pump, an outflow cylinder, a supporting frame and a measuring unit; the permeation pressure chamber, the syringe pump and the outflow cylinder are connected with the supporting frame through fasteners; cavities are arranged in a sample cap and a sample base in the permeation pressure chamber; the syringe pump is arranged on the left or right side of the permeation pressure chamber; the outflow cylinder is arranged below the permeation pressure chamber; the measuring unit is used for collecting the speed of the fluid injected by the syringe pump, the pressure of the fluid at both ends of the sample in the permeation pressure chamber and the temperature of the fluid; the application can not only study the mechanism of the fluid density and field acceleration on the permeation under the driving of the pressure energy gradient in the centrifuge supergravity field, but also study the mechanism of the fluid density and field acceleration on the permeation under the driving of the pressure energy gradient in the earth gravity field; the influence of the temperature change of the fluid on the permeation coefficient in the permeation test can be considered, and the time when the permeation reaches stability and the size of the permeation speed can be obtained through the measuring unit.

Description

Technical Field

[0001] This invention relates to a centrifuge-based pure pressure energy gradient permeation test device under a centrifugal hypergravity field, belonging to the technical field of porous media permeation characteristic analysis. Background Technology

[0002] Darcy's law is a fundamental theory describing the permeation of fluids in porous media. Darcy's law states that permeation is driven by a gradient of mechanical energy, with fluids flowing from areas of higher mechanical energy to areas of lower mechanical energy in porous media. Currently, the mathematical expression of Darcy's law varies in gravitational fields, and its expression in the hypergravity field of a centrifuge also differs from that in a gravitational field. This diversity in the expression of Darcy's law indicates differing understandings, leading to frequent deviations and ambiguities in the analysis of seepage phenomena. Therefore, a unified understanding of the mechanisms by which the various variables in Darcy's law affect permeation, and the establishment of appropriate expressions for Darcy's law in different application scenarios and force fields, are of great significance. It is essential to experimentally investigate the influence of fluid gravity (density and field acceleration) and subsequently establish appropriate expressions for Darcy's law in different application scenarios and force fields.

[0003] Darcy's permeation is driven by both potential energy and pressure energy, but the effects of density and field acceleration on these two factors remain unclear. Although there are various existing permeation testing methods, in a gravitational field, indoor permeation tests are divided into six methods: constant head method, downward head and constant tail method, downward head and rising tail method, constant flow rate method, constant volume-constant head method, and constant volume-downward head and rising tail method. In centrifuge-based permeation tests in hypergravity fields, constant head method, downward head and constant tail method, and downward head and rising tail method are already available. However, in existing permeation testing methods, permeation is driven by both potential energy and pressure energy, making it difficult to distinguish the effects of each on seepage and thus failing to achieve the goal of exploring the mechanism of density and field acceleration on permeation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a centrifuge ultragravity field pure pressure energy gradient permeation test device. By conducting pure pressure energy driven permeation tests with fluids of different densities in different field acceleration environments, researchers can explore the mechanism of the effect of density and field acceleration on pressure energy, and technicians can also determine the permeability coefficient of low-permeability porous media.

[0005] To achieve the above objectives, the present invention provides a centrifuge ultragravity field pure pressure energy gradient osmosis test device, comprising an osmosis pressure chamber, an injection pump, an outlet flow cylinder, a support frame, and a measuring unit;

[0006] The osmotic pressure chamber, injection pump, and outlet flow cylinder are connected to the support frame by fasteners;

[0007] The sample cap and sample base in the osmotic pressure chamber are each provided with a cavity.

[0008] The injection pump is located to the left or right of the osmotic pressure chamber;

[0009] The outlet flow cylinder is located below the osmotic pressure chamber;

[0010] The measuring unit is used to collect the speed of the fluid injected by the injection pump, the pressure of the fluid at both ends of the sample in the osmotic pressure chamber, and the temperature of the fluid.

[0011] Preferably, the measuring unit includes a sensor data acquisition device, several water pressure sensors for measuring the fluid pressure at both ends of the sample in the osmotic pressure chamber, several temperature sensors for measuring the fluid temperature, and several laser displacement sensors for measuring the actual velocity of the fluid injected by the injection pump.

[0012] The water pressure sensor is installed at both ends of the sample in the osmotic pressure chamber, the laser displacement sensor is installed at the left end of the injection pump, the water pressure sensor is installed at the center of the bottom of the flow cylinder, and the temperature sensor is installed next to the water pressure sensor at the bottom of the flow cylinder; the output ends of the water pressure sensor, temperature sensor and laser displacement sensor are all electrically connected to the input end of the sensor data acquisition device.

[0013] Preferably, the osmotic pressure chamber includes: a circular top plate, an outer cover, a circular bottom plate, a sample cap, and a sample base;

[0014] The circular top plate is equipped with an vent for venting air from the osmotic pressure chamber and an inlet for passing through the inlet pipe, with an inlet valve installed at the inlet position. An outer cover is positioned between the circular top plate and the circular base plate. The circular base plate is equipped with an outlet for passing through the outlet pipe and a confining pressure hole connecting the osmotic pressure chamber and the confining pressure pipe, with corresponding outlet and confining pressure valves installed. A sample base for placing the sample is fixed at the center of the circular base plate, and a sample cap is placed on the sample. During the filling of the pressure chamber with water, the vent serves to vent air from the osmotic pressure chamber. When the pressure chamber is full of water, the vent is tightened with bolts to prevent air leakage from the osmotic pressure chamber.

[0015] To ensure uniform distribution of the permeating fluid, a cavity is provided inside the sample cap and a cavity is provided inside the sample base. Two water pressure sensors are installed in the two cavities to measure the pressure values ​​at both ends of the sample. The pipes connecting the cavities are bent upwards, with the length of the upward bend being 1-5 mm longer than the sample radius. This prevents the fluid in the upper part of the cavity from flowing out due to the potential energy difference with the outlet hole of the sample base, which could lead to unsaturation in the upper part of the sample or inconsistent flow field distribution between the upper and lower parts.

[0016] Preferably, the cavity is a frustum-shaped cavity with a gradually changing cross-sectional area. The cavity is designed as a frustum-shaped cavity with a gradually changing cross-sectional area to allow the fluid to transition smoothly and disperse evenly while minimizing mechanical energy loss.

[0017] Preferably, the inlet and outlet lines form a permeation line, with the inlet line connecting the syringe and sample cap on the injection pump, and the outlet line connecting the outlet valve of the osmotic pressure chamber chassis to the atmosphere.

[0018] Preferably, the permeation tubing is arranged on the same plane as the axial section of the cylindrical specimen perpendicular to the support frame. During the centrifuge hypergravity field test, the centrifuge arm axis is located on the axial section of the cylindrical specimen perpendicular to the support frame, which can prevent the permeation tubing from being thrown off due to centrifugal force.

[0019] Preferably, the permeation pipeline is a metal pipe or a rigid thermoplastic pipe to prevent greater mechanical energy loss and errors caused by deformation of the pipeline material transporting the fluid due to pressure changes.

[0020] Preferably, the end of the outflow pipe is attached to the side wall of the outflow cylinder with a clamp, forming an acute angle with the side wall so that the outflow fluid slides down the side wall of the outflow cylinder instead of dripping into the outflow cylinder.

[0021] Preferably, the top of the flow meter is provided with a cover plate to prevent the fluid in the flow meter from evaporating due to the wind caused by the centrifuge rotation, which would affect the measurement of the outflow rate.

[0022] Preferably, the support frame is made of stainless steel.

[0023] The beneficial effects achieved by this invention are as follows:

[0024] (1) The device of the present invention can be used to study the mechanism of fluid density and field acceleration on the infiltration when fluid infiltrates only under the drive of pressure energy gradient in the centrifuge hypergravity field and in the Earth's gravity field.

[0025] (2) The present invention can take into account the effect of fluid temperature change on permeability coefficient in permeation test, and can obtain the time for permeation to reach stability and the magnitude of permeation rate through water pressure sensor. Attached Figure Description

[0026] Figure 1a 1b and 1c are the front view, left view and top view of the present invention, respectively;

[0027] Figure 2a 2b and 2c are the front view, left view, and top view of the osmotic pressure chamber, respectively;

[0028] Figure 3 This is a 1-1 cross-sectional view of the osmotic pressure chamber;

[0029] Figure 4a 4b and 4c are the front view, left view and top view of the sample holder in the osmotic pressure chamber, respectively.

[0030] Figure 5a 5b and 5c are the front view, left view, and top view of the support frame, respectively.

[0031] Meaning of the reference numerals in the attached figures: 1-Osmotic pressure chamber; 2-Injection pump; 3-Outlet flow cylinder; 4-Support frame; 5-Water pressure sensor; 6-Temperature sensor; 7-Laser displacement sensor; 8-Sample holder in the osmotic pressure chamber; 9-Containing pressure tube; 10-Lifting ring; 11-Cavity; 12-Circular top plate; 13-Outer cover; 14-Circular base plate; 15-Sample cap; 16-Sample base; 17-Fixing bolt. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0033] Example 1

[0034] This invention relates to a centrifuge ultragravity field pure pressure energy gradient osmosis test device, comprising an osmosis pressure chamber 1, an injection pump 2, an outlet flow cylinder 3, a support frame 4, and a measuring unit;

[0035] The osmotic pressure chamber 1 includes a circular top plate 12, an outer cover 13, a circular base 14, a sample cap 15, a sample base 16, and fixing bolts 17. The circular top plate 12 has a vent hole at its center, which serves to expel air from the osmotic pressure chamber 1 during water filling. When the pressure chamber is full, the vent hole is tightened with bolts to prevent air leakage. There is also an inlet hole through which the inlet pipe passes, and an inlet valve is installed at the inlet hole location. The outer cover 13 is a transparent acrylic cylinder for easy observation of the sample's condition. The circular base 14 has an outlet hole and a confining pressure hole on its side, with corresponding outlet valves and confining pressure valves installed. There is also a wiring hole for the data cable of the water pressure sensor 5. A sample base 16 is fixed at the center of the base 14. During the test, the sample base... A sample is placed on the sample base 16, and a sample cap 15 is placed on the sample. In order to make the permeating fluid evenly distributed, a cavity 11 is set in the sample cap 15 and the sample base 16. Two water pressure sensors 5 are set in the two cavities 11 to directly measure the pressure values ​​at the left and right ends of the sample and to monitor whether the permeation test has reached a stable flow. The pipe connecting the cavity (11) is slightly curved upward. In this embodiment, it is a Z-shaped bend upward. The length of the upward bend is 22.00 mm, which is slightly larger than the radius of the cylindrical sample 19.55 mm in this embodiment. This prevents the fluid in the upper part of the cavity 11 from flowing out due to the potential energy difference with the outlet hole of the sample base 16, which would cause the upper part of the sample to be unsaturated or the distribution of the flow field in the upper and lower parts to be inconsistent.

[0036] A small hole is made in the center of the sample cap 15, sample base 16 and cavity 11 away from the sample end in the osmotic pressure chamber 1 to connect the inlet pipe. Another small hole is made next to the center of cavity 11 to install water pressure sensor 5. The line of water pressure sensor 5 passes through the circular base 14 and is led out of the osmotic pressure chamber 1 along the wire hole at the bottom of the circular base 14. The inlet pipe at the sample cap 15 end passes through the top plate 12 and is connected to the syringe on the injection pump 2. The outlet pipe at the sample base 16 end passes through the circular base 14 and then through the middle plate of the support frame 4 to reach the top of the outlet flow cylinder 3. The end of the outlet pipe is fixed to the side wall of the outlet flow cylinder 3 with a clamp and forms a 10° angle with the side wall to ensure that the outflowing fluid slides down the side wall instead of dripping onto the liquid surface in the outlet flow cylinder 3.

[0037] The water pressure sensor 5 head is threaded, allowing for easy disassembly and replacement of the water pressure sensor 5 with the corresponding range according to the test pressure, making it convenient to use.

[0038] The measurement unit includes a sensor data acquisition device, several water pressure sensors 5 for measuring the fluid pressure at both ends of the sample, several temperature sensors 6 for measuring the fluid temperature, and several laser displacement sensors 7 for measuring the speed of the fluid injected by the injection pump 2. Two water pressure sensors 5 are respectively set at both ends of the sample to monitor the magnitude of the fluid pressure at both ends of the sample and whether the difference is stable. One water pressure sensor 5 is placed at the bottom center of the outflow cylinder 3 to monitor the pressure change at the bottom of the outflow cylinder 3. One temperature sensor 6 is set at the bottom of the outflow cylinder 3 to monitor the change of fluid temperature during the permeation test. One laser displacement sensor 7 is set at the left end of the injection pump 2 to monitor the actual movement speed of the syringe piston on the injection pump 2 during the test, and the actual permeation speed of the permeation test fluid is calculated based on the actual movement speed of the syringe piston.

[0039] The output terminals of water pressure sensor 5, temperature sensor 6, and laser displacement sensor 7 are all electrically connected to the input terminal of the sensor data acquisition device; that is, the data measured by water pressure sensor 5, temperature sensor 6, and laser displacement sensor 7 are transmitted to the sensor data acquisition device for recording via wires, facilitating subsequent analysis.

[0040] The measurement unit can monitor the fluid permeation rate, pressure, and temperature of the sample in real time during the permeation process, thereby obtaining the permeation rate of the permeation test and the time when the permeation reaches a stable state. It can also correct for changes in the permeability coefficient of porous media caused by temperature variations, providing accurate data for analyzing the direct relationship between permeation rate and fluid density and field acceleration.

[0041] The confining pressure of the sample in the osmotic pressure chamber 1 is provided by a metal or rigid thermoplastic tube that communicates with the interior of the osmotic pressure chamber 1. This tube is called the confining pressure tube 9. The confining pressure tube 9 is fixed to the support frame 4 and extends to the centrifuge arm and is tied to the centrifuge arm during the centrifuge test.

[0042] When conducting a pure pressure energy gradient osmosis test, the pressure chamber is positioned perpendicular to the centrifuge's hypergravity field. One end of the sample cap 15 is unsupported. Under the combined effect of gravity and centrifugal force (centrifuge hypergravity field test), the sample position will shift, causing errors in the test. Therefore, after sample loading, the sample holder 8 is placed on the side of the sample furthest from the centrifuge's rotation axis to avoid this error.

[0043] The top of the support frame 4 and the support screw is equipped with a lifting ring 10, which makes it easy to hoist the device into the centrifuge basket and also makes it easy to move the device.

[0044] The support frame 4 is made of stainless steel, and the pipes are made of metal or rigid thermoplastic pipes.

[0045] The specific working process of this invention:

[0046] Step 1: Fill the cavity 11 of the sample base 16 with test fluid, and place the sample and sample cap 15 in sequence (when the sample is a rigid sample, there is no risk of particles clogging the permeable stone, adding filter paper is not necessary, and adding permeable stone will change the seepage path length, so no permeable stone or filter paper is added to the two ends of the sample).

[0047] Step 2: Place the rubber membrane inside the membrane holder, fold both ends out of the holder, and use a suction bulb to draw air through the suction hole to make the membrane adhere tightly to the inner wall of the membrane holder. Place the membrane on the sample, release the air, fold up both ends of the rubber membrane, and remove the membrane holder. Secure both ends of the rubber membrane to the sample base 16 and sample cap 15 with rubber bands. Place the sample holder 8 on one side of the sample, which is located away from the centrifuge shaft after the osmotic pressure chamber 1 is laid horizontally.

[0048] Step 3: Install the outer cover 13 and the circular top plate 12, tighten the fixing bolts 17 to prevent water leakage, and check whether each pipe joint is leaking;

[0049] Step 4: Unscrew the vent bolt and fill the osmotic pressure chamber 1 with water. When the osmotic pressure chamber 1 is almost full of water, reduce the water inlet speed. When water overflows from the vent, screw the vent back on.

[0050] Step 5: Place the osmotic pressure chamber 1 horizontally. After the centrifuge reaches the target speed and the test officially begins, the sample is vertical. Every point on the sample axis is equidistant from the zero potential energy reference surface of the centrifuge's hypergravity field, and the potential energy at the inlet and outlet positions is equal.

[0051] Step 6: Then raise the water-filled confining pressure pipe 9 to a certain height and close the solenoid valve on the confining pressure pipe 9. The water level in the confining pressure pipe 9 can ensure that the confining pressure is greater than the inflow pressure during the test.

[0052] Step 7: Sensor Installation. Connect the water pressure sensor 5 and temperature sensor 6 to the pre-reserved interface at the bottom of the flow cylinder 3. Install the laser displacement sensor 7 to the left of the syringe pump 2. Connect the sensor output to the input of the sensor data acquisition device.

[0053] Step 8: Use a level to check whether the middle plate and bottom plate of the support frame 4 are level. If they are not level, adjust them to be level.

[0054] Step 9: Set the outflow rate on syringe pump 2. Start the centrifuge, and after reaching the target acceleration, open the solenoid valve to generate the required confining pressure on the rubber diaphragm using the water column;

[0055] Step 10: Monitor the outflow rate in flow cylinder 3, and stop the test after 6 hours.

[0056] Steps one through ten were repeated using several fluids of different densities at several centrifuge speeds. The relationship between pressure difference and seepage velocity across samples of the same density fluid at different centrifuge speeds and fluids of different densities at the same centrifuge speeds was plotted. The expressions for fluid density and field acceleration in permeation driven purely by pressure energy gradients were summarized and compared with the existing Darcy's law expression.

[0057]

[0058] The results are compared to verify their accuracy. Here, μ is the dynamic viscosity of the fluid, v is the seepage velocity, L is the seepage path length, and K is the intrinsic permeability coefficient of the sample.

[0059] In addition, during the centrifugal force field test, the pressure value u at the bottom of the flow cylinder is measured, and the real-time outflow rate is calculated and compared with the inflow rate at the same time to determine whether the test has reached a stable state.

[0060] The formula for calculating the pressure value u is:

[0061]

[0062] In the formula, r1 and r2 are the distances between the liquid level inside the flow cylinder 3 and the bottom inner surface of the flow cylinder 3 and the center of the centrifuge shaft, respectively.

[0063] Example 2 differs from Example 1 in that the water pressure sensor 5, which monitors the pressure change at the bottom of the flow cylinder 3, is removed during the gravity field test. Instead, a high-precision electronic scale is used to weigh the mass of the outflowing fluid. The data output terminal of the electronic scale is connected to a computer to collect data in real time.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A centrifuge-based pure pressure energy gradient osmosis test apparatus under a hypergravity field, characterized in that, It includes an osmotic pressure chamber (1), an injection pump (2), an outlet flow cylinder (3), a support frame (4), and a measuring unit; The osmotic pressure chamber (1), injection pump (2), and outlet flow cylinder (3) are connected to the support frame (4) by fasteners; The sample cap (15) and sample base (16) in the osmotic pressure chamber (1) are each provided with a cavity; The injection pump (2) is located to the left or right of the osmotic pressure chamber (1); The outlet flow cylinder (3) is located below the osmotic pressure chamber (1); The measuring unit is used to collect the speed of the fluid injected by the injection pump (2), the pressure of the fluid at both ends of the sample in the osmotic pressure chamber (1), and the temperature of the fluid; The osmotic pressure chamber (1) includes: a circular top plate (12), an outer cover (13), a circular bottom plate (14), a sample cap (15), and a sample base (16); The circular top plate (12) is provided with an exhaust hole for discharging air from the osmotic pressure chamber (1) and an inlet hole for passing through the inlet pipe. An inlet valve is installed at the inlet hole position. The outer cover (13) is located between the circular top plate (12) and the circular base plate (14). The circular base plate (14) is provided with an outlet hole for passing through the outlet pipe and a confining pressure hole for connecting the osmotic pressure chamber (1) and the confining pressure pipe (9). An outlet valve and a confining pressure valve are installed accordingly. A sample base (16) for placing the sample is fixed at the center of the circular base plate (14). A sample cap (15) is placed on the sample. The sample support (8) is placed on one side of the sample. This side is located away from the centrifuge shaft after the osmotic pressure chamber (1) is laid horizontally. A cavity (11) is provided inside the sample cap (15) and the sample base (16); two water pressure sensors (5) are set in the two cavities (11) to measure the pressure values ​​at both ends of the sample. The inlet and outlet pipes constitute the permeation pipes; the permeation pipes are arranged on the same plane of the cylindrical sample perpendicular to the axial section of the middle plate of the support frame (4), and the centrifuge arm axis is located on the axial section of the cylindrical sample perpendicular to the middle plate of the support frame (4) during the centrifuge hypergravity field test.

2. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 1, characterized in that, The measuring unit includes a sensor data acquisition device, several water pressure sensors (5) for measuring the fluid pressure at both ends of the sample in the osmotic pressure chamber (1), several temperature sensors (6) for measuring the fluid temperature, and several laser displacement sensors (7) for measuring the actual speed of the fluid injected by the injection pump (2). The water pressure sensor (5) is installed at both ends of the sample in the osmotic pressure chamber (1), the laser displacement sensor (7) is installed at the left end of the injection pump (2), the water pressure sensor (5) is installed at the center of the bottom of the flow cylinder (3), and the temperature sensor (6) is installed next to the water pressure sensor (5) at the bottom of the flow cylinder (3); the output ends of the water pressure sensor (5), the temperature sensor (6) and the laser displacement sensor (7) are all electrically connected to the input end of the sensor data acquisition device.

3. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 1, characterized in that, The pipe connecting the cavity (11) is bent upwards, and the length of the upward bend is 1~5mm longer than the radius of the sample.

4. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 1, characterized in that, The cavity (11) is a frustum-shaped cavity with a gradually changing cross-sectional area.

5. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 3, characterized in that, The inlet line is connected to the syringe and sample cap (15) on the injection pump (2), and the outlet line is connected to the outlet valve of the circular chassis (14) and the atmosphere.

6. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 5, characterized in that, The permeation pipeline is a metal pipe or a rigid thermoplastic pipe.

7. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 3, characterized in that, The end of the outflow pipe is attached to the side wall of the outflow cylinder (3) with a clamp, and forms an acute angle with the side wall so that the outflow fluid slides down the side wall of the outflow cylinder (3).

8. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 1, characterized in that, The top of the outlet cylinder (3) is provided with a cover plate.

9. The centrifuge-based ultragravity field pure pressure energy gradient osmosis test apparatus according to claim 1, characterized in that, The support frame (4) is made of stainless steel.

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