A method for designing the ventilation area of ​​a water tank, a water tank, a storage medium and an electronic device

Abstract

The present invention belongs to the technical field of drainage devices, and discloses a method for designing the ventilation area of ​​a water tank, a water tank, a storage medium and an electronic device. The top of the water tank is provided with a ventilation slit with an area that can be adjusted in real time, and the bottom of the water tank is provided with a water outlet. The present invention establishes a judgment model for whether bubbles are generated during the drainage process of the water tank, and then on this basis establishes the relationship between the water outlet and the size of the ventilation slit that meets the condition of not generating bubbles during the drainage process, thereby obtaining a reasonable design range for the size of the ventilation slit, and then selects a reasonable size of the ventilation slit according to the actual needs of the ventilation slit of the water tank, so that the designed ventilation slit size can ensure the drainage efficiency and avoid the environment inside the water tank from being polluted by the outside world as much as possible, thereby achieving a reasonable balance between the two, providing a brand-new idea for the existing water tank design, and its progressive significance is self-evident.

Description

Technical Field

[0001] The invention belongs to the technical field of drainage devices, and in particular relates to a design method for the ventilation area of ​​a water tank, a water tank, a storage medium and an electronic device. Background Art

[0002] A water tank is a common water storage device in life and industry. Its drainage efficiency is often an important indicator of its quality. The drainage position of a water tank is generally set at the bottom. When the bottom drain port is opened, if the ventilation above the water tank is not smooth, the bottom drain port will be affected by the external atmospheric pressure and will take in air upward while draining water, generating bubbles, which will enter the air cavity above the water surface to maintain the air pressure balance inside and outside the water tank. In the process of generating bubbles, the drainage speed of the water tank will be significantly reduced. If a ventilation slit is set on the top of the water tank, the air intake of the bottom drain hole can be reduced, thereby correspondingly increasing the drainage speed. Figure 3 The figure shows the drainage speed of the water tank under three different ventilation conditions. However, due to the need to ensure the cleanliness of the internal environment of the water tank, the vent hole on the top should be as small as possible to avoid pollution to the environment inside the water tank as much as possible. However, it is difficult to achieve a balance between the two when designing the ventilation seam of the water tank in the prior art. Either the top ventilation seam is too large, which makes the inside of the water tank easily polluted, or the ventilation seam is too small or there is no ventilation seam, which leads to low drainage efficiency of the water tank. Therefore, a design method for the ventilation seam of the water tank is urgently needed to achieve a balance between the size of the ventilation seam area and the drainage efficiency. Summary of the invention

[0003] The purpose of the present invention is to provide a method for designing the ventilation area of ​​a water tank, a water tank, a storage medium and an electronic device, so as to solve the problems raised in the above-mentioned background technology.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for designing the ventilation area of ​​a water tank, wherein a ventilation slit with an area that can be adjusted in real time is provided on the top of the water tank, and a water outlet is provided on the bottom of the water tank. The drainage process includes the following steps:

[0006] S1. Establish a judgment model for whether bubbles appear during drainage;

[0007] S2. Establish the relationship between the size of the water outlet and the vent hole that does not generate bubbles during drainage: According to the force balance of the water outlet at the bottom of the water tank, the critical condition for bubbles to enter the water tank from the bottom water outlet is obtained, and its critical expression is: Where P1 is the relative pressure in the top area of ​​the water tank, in Pa; P s P is the additional pressure of surface tension at the orifice, in Pa, and its size is determined according to the actual size of the water outlet of the water tank; atmis the relative atmospheric pressure, in Pa; ρ w is the density of water in kg / m 3 ; g is the acceleration due to gravity, in m / s 2 ;

[0008] S2. Establish the relationship between the size of the water outlet and the venting slit that satisfies the condition of no bubble generation during drainage: Based on the conservation of mass and energy during the emptying of the water tank, the relationship between the pressure at the top of the water surface and the water depth is obtained. Combined with the critical condition for bubbles to enter the water tank from the bottom water outlet, the conditional expression for no bubble generation during drainage is obtained:

[0009]

[0010] ζ0 is the local head loss coefficient of the bottom outlet, dimensionless; z1 and z2 are the position heads of the water surface in the water tank and the outlet, in m; v1 and v2 are the average flow velocities of the water surface in the water tank and the liquid surface at the outlet, in m / s; ρ a is the density of air, in kg / m 3 ; k0 is the local head loss coefficient of the ventilation gap, dimensionless; h is the depth of water in the water tank, t is time; ε s is the contraction coefficient of the ventilation gap, dimensionless; A0 is the area of ​​the water outlet hole at the bottom of the water tank, A s is the area of ​​the top ventilation slit.

[0011] S3. Calculate the minimum ventilation slit area required to avoid bubbles from being generated during drainage, and adjust the ventilation slit area of ​​the water tank to implement drainage.

[0012] A water tank has a ventilation slit on the top and a water outlet hole on the bottom. The ventilation area design method of the water tank is used to adjust the area of ​​the ventilation slit in real time and determine the size relationship between the water outlet hole and the ventilation slit.

[0013] A storage medium stores a computer program, wherein the computer program includes a sequence and program code for controlling an execution process, and the execution process includes the above-mentioned method for designing the ventilation area of ​​a water tank.

[0014] An electronic device comprises a storage device, a processor and a display module. The storage device comprises the above-mentioned storage medium. The processor runs a computer program in the storage medium. The display module is used to output calculation results.

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. The present invention establishes a judgment model for whether bubbles are generated during the drainage process, and then establishes the relationship between the water outlet hole and the size of the ventilation slot that meets the condition of not generating bubbles during the drainage process, thereby finally obtaining a reasonable design range of the ventilation slot, and then selecting a reasonable ventilation slot size according to the actual needs of the water tank ventilation slot, so that the designed ventilation slot size can ensure the drainage efficiency and avoid the environment inside the water tank from being polluted by the outside world as much as possible, thereby achieving a reasonable balance between the two, providing a new idea for the existing water tank design, and its progressive significance is self-evident.

[0017] 2. The present invention integrates the design method and process conversion program code into electronic equipment or storage media, so that the design method of the present invention can be separated from manuscript paper and the mental calculation of designers, and the size of the ventilation gap can be designed in real time according to design requirements and on-site conditions, freeing the hands of designers, giving them higher design efficiency, and further reducing the probability of design errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the appearance of the water tank of the present invention;

[0019] Figure 2 It is a schematic diagram of the cross-section model of the water tank of the present invention;

[0020] Figure 3 It is a schematic diagram of the drainage efficiency of the water tank under three different ventilation conditions;

[0021] Figure 4 This is a comparison chart of the experimental and model results of the present invention.

[0022] In the figure: 1. Water tank; 2. Ventilation slit; 3. Water outlet. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figures 1 to 4 As shown, the embodiment of the present invention provides a design method for the ventilation area of ​​a water tank and its use. Considering the influence of bubbles at the bottom orifice on the drainage process, firstly, a judgment condition for whether bubbles appear during the drainage process is established. According to the force balance at the orifice at the bottom of the water tank, the critical condition expression for bubbles to enter the water tank is obtained:

[0025]

[0026] Where P1 is the relative pressure in the top area of ​​the water tank, in Pa; P s P is the additional pressure of surface tension at the orifice, in Pa, and can be determined according to the actual size of the water outlet of the water tank; atm is the relative atmospheric pressure, in Pa; ρ w is the density of water in kg / m 3 ; g is the acceleration due to gravity, in m / s 2 .

[0027] Secondly, the relationship between the size of the water outlet and the vent is established to meet the condition of no bubbles during drainage. Based on the mass conservation and energy conservation equations, the formula for the change of the top air pressure with the water depth during the water tank emptying process is derived. The derivation steps are as follows:

[0028] Assuming that during the emptying process, the water depth change value in the water tank within a very short time dt is dh, and the outflow velocity of the bottom orifice is v2, according to the law of conservation of energy, the Bernoulli equation is formulated for the gas-liquid interface aa inside the water tank and the outer interface bb of the orifice at the bottom of the water tank:

[0029]

[0030] Where P1 is the relative pressure in the top area of ​​the water tank, in Pa; P2=0 is the pressure at the interface bb, in Pa, which is approximately equal to the atmospheric pressure (relative pressure); ζ0 is the local head loss coefficient of the bottom water outlet, dimensionless; z1 and z2 are the position heads at the interfaces aa and bb, in m; v1 and v2 are the average flow velocities of the liquid surface at the interfaces aa and bb, in m / s.

[0031] According to the law of conservation of mass, the continuity equation between interfaces aa and bb can be listed as:

[0032] v1A1=v2A2 (3)

[0033] Where A1 is the cross-sectional area of ​​the water tank, in m 2 ; A2 is the contraction cross-sectional area at the interface bb, in m 2 ;

[0034] The contraction cross-sectional area A2 can be calculated using the following formula:

[0035] A2=ε0A0 (4)

[0036] Where ε0 is the contraction coefficient of the bottom opening, dimensionless; A0 is the area of ​​the bottom opening of the water tank, unit is m 2 ;

[0037] Assume that the air velocity at the top vent is v a, and the water heads at the interfaces cc and dd are very close. According to the law of conservation of energy, the Bernoulli equation is formulated for the inner and outer cross-sections cc and dd of the ventilation seam at the top of the water tank:

[0038]

[0039] Where P3=0 is the pressure at the cc section, which is approximately equal to the standard atmospheric pressure (relative pressure), in Pa; P4 is the pressure at the dd section, that is, the air pressure in the top area of ​​the water tank, in Pa; ρ a is the density of air, kg / m 3 ; k0 is the local head loss coefficient of the ventilation joint, dimensionless;

[0040] Assume that in time dt, the volume of liquid flowing out from the orifice at the bottom of the water tank is dV w It can be calculated by the following formula:

[0041]

[0042] v2 can be obtained by the following steps: Substitute formula (4) into formula (3) to obtain the relationship between v1 and v2, and then substitute the relationship into formula (2). After sorting, the relationship between v2 and P1 can be obtained and substituted into formula (6).

[0043] Assume that in the same time dt, the volume of gas entering the water tank from the vent at the top of the water tank is dV a It can be calculated by the following formula:

[0044]

[0045] where ε s is the shrinkage coefficient of the ventilation gap, dimensionless; v a It can be derived from formula (4);

[0046] Assume that in a very short time dt, the volume of liquid flowing out of the tank is dV w Equal to the volume of air entering the water tank dV a ,Right now:

[0047] dV a =dV w (8)

[0048] Substituting formula (6) and formula (7) into formula (8), we can get the relationship between the air pressure P1 at the top of the water tank and the water depth h during the emptying process:

[0049] P1=Kh (9-1)

[0050] in,

[0051] Combining equation (1) with equation (9), we can obtain the conditional expression for not generating bubbles:

[0052]

[0053] That is, the water outlet area A0 at the bottom of the water tank and the vent area A s If the relationship (10) is satisfied, it can be ensured that no bubbles are generated at the bottom of the water tank during drainage. When the water is drained, there is still 10mm of water in the water tank. Therefore, if h = 10mm, it just satisfies the relationship (10). At this time, A s It is the minimum ventilation area required to design without generating bubbles during the drainage process.

[0054] For this experiment, it is known that g = 9.8 m / s 2 , ρ w =1000kg / m 3 , ρ a =1.29kg / m 3 , k0=0.06, ε0=0.64, ε s =0.64, ζ0=0.06, A1=0.04m 2 , A0=1.256×10 -3 m 2 , P s =20Pa, P atm =0Pa, h=0.01m, The value of is too small and can be ignored. Substituting the above data into formula (10), we can get the vent area A s Need to meet condition A s ≥2.36×10 -5 m 2 =23.6mm 2 Considering that in actual water tank use, the smaller the vent area, the lower the risk of water contamination in the water tank, so consider a smaller area A s =30mm 2 , and repeated the drainage test. The experimental results show that the emptying time is 25.6s, which is better than A s =0mm 2 With A s =5mm 2 The efficiency of the two working conditions has been greatly improved. Therefore, this calculation method is highly feasible for guiding the design of the water tank ventilation area.

[0055] Then, the drainage efficiency calculation formula under the above insufficient ventilation conditions is established. Assuming that the change value of the water depth inside the water tank is dh within the time dt, v1 in formula (2) can be expressed as:

[0056]

[0057] Substituting formulas (3), (4) and (11) into formula (2), we can obtain:

[0058]

[0059] Substituting formula (9) into formula (12) yields the differential equation expression for the change in water depth dh in the water tank within a very short time dt:

[0060]

[0061] in

[0062]

[0063] Select different integral regions for integration to obtain the calculation formula for the change of water depth in the water tank over time and the time required for the water tank to be emptied. Specifically, when the integral domain on the left side of formula (13-1) is set to [0, t] and the integral domain on the right side of the formula is set to [H0, h] for integration, the calculation formula for the change of water depth in the water tank over time during the emptying process can be obtained:

[0064]

[0065] Where H0 is the initial water depth in the water tank, m;

[0066] The integral domain of the left side of formula (13-1) is set to [0,T e ], when the integral domain on the right side of the formula is set to [H0,0] for integration, the time T required to complete the emptying can be obtained. e :

[0067]

[0068] Comparison of model calculation data and experimental data Figure 4 As shown, the curves fit well, indicating that the prediction model is feasible.

[0069] The design method obtained in the above embodiment can be integrated into a related device such as a storage medium, which stores a computer program. The computer program includes a control execution process sequence and a program code, and the execution process includes the three basic steps of implementing the above design:

[0070] The first step is to establish a judgment model for whether bubbles appear during drainage;

[0071] The second step is to establish the size relationship between the water outlet and the ventilation slit to meet the condition of no bubbles generated during drainage;

[0072] The third step is to calculate the minimum ventilation slit area required to avoid bubble generation during drainage, and adjust the ventilation slit area of ​​the water tank to implement drainage.

[0073] The storage medium is not limited to hard disks, flash memories, etc. After being connected to a computer device, the above-mentioned design steps can be called up, and the basic algorithm can be used to design the size of ventilation gaps at construction or related drainage sites. It is flexible and has a wide range of applications. Combined with existing storage media, it can be plug-and-play, eliminating the need for manual design and calculation in the office, which takes a lot of time.

[0074] Another example is an electronic device, which has several basic modules such as a memory, a processor, an input module and a display module. The memory of the electronic device stores the above-mentioned basic steps for implementing the ventilation seam design and the algorithm process of the implementation method. The processor is configured to execute the above-mentioned design steps and algorithms. The user can input relevant parameters of the site or the water tank to be designed through the input module, and the display module intuitively outputs the design results after calculation. The device is professionally used in this field and has strong adaptability. Since the device can work independently, its stability is relatively better and it can be lightweight in design. For example, handheld computers, smart watches, etc. can implement the design of the present invention.

[0075] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for designing the ventilation area of ​​a water tank, wherein a ventilation slit with an area that can be adjusted in real time is provided on the top of the water tank, and a water outlet is provided on the bottom of the water tank, characterized in that: The drainage process includes the following steps: S1. Establish a judgment model for whether bubbles appear during drainage: According to the force balance of the water outlet at the bottom of the water tank, the critical condition for bubbles to enter the water tank from the bottom water outlet is obtained, and its critical expression is: Where P1 is the relative pressure in the top area of ​​the water tank, in Pa; P s P is the additional pressure of surface tension at the orifice, in Pa, and its size is determined according to the actual size of the water outlet of the water tank; atm is the relative atmospheric pressure, in Pa; ρ w is the density of water in kg / m 3 ; g is the acceleration due to gravity, in m / s 2 ; h is the depth of water in the water tank, t is the time; S2. Establish the relationship between the size of the water outlet and the venting slit that satisfies the condition of no bubble generation during drainage: Based on the conservation of mass and energy during the emptying of the water tank, the relationship between the pressure at the top of the water surface and the water depth is obtained. Combined with the critical condition for bubbles to enter the water tank from the bottom water outlet, the conditional expression for no bubble generation during drainage is obtained: ζ0 is the local head loss coefficient of the bottom outlet, dimensionless; ρ a is the density of air, in kg / m 3 ; k0 is the local head loss coefficient of the ventilation joint, dimensionless; ε s is the contraction coefficient of the ventilation gap, dimensionless; A0 is the area of ​​the water outlet hole at the bottom of the water tank, A s is the area of ​​the top ventilation slit; A1 is the cross-sectional area of ​​the water tank; ε0 is the contraction coefficient of the bottom orifice; S3. Calculate the minimum ventilation slit area required to avoid bubble generation during drainage according to the formula in S2 above, and adjust the ventilation slit area to implement drainage.

2. A water tank, wherein a ventilation slit is provided at the top of the water tank, and a water outlet is provided at the bottom of the water tank, characterized in that: The method for designing the ventilation area of ​​a water tank as claimed in claim 1 is used to adjust the area of ​​the ventilation slit in real time and determine the size relationship between the water outlet and the ventilation slit.

3. A storage medium, characterized in that: The storage medium stores a computer program, which includes a sequence and program code for controlling an execution process, and the execution process includes the method for designing the ventilation area of ​​the water tank according to claim 1.

4. An electronic device, comprising a storage device, a processor and a display module, characterized in that: The storage device includes the storage medium as claimed in claim 3, the processor runs the computer program in the storage medium, and the display module is used to output the calculation result.

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