Method for calculating waterproof/dust aperture of sound barrier
阅读说明：本技术 一种计算声屏障防水/尘孔径的方法 (Method for calculating waterproof/dust aperture of sound barrier ) 是由 许树东 于 2021-09-01 设计创作，主要内容包括：本发明一种计算声屏障防水/尘孔径的方法,属于声屏障技术领域,本发明克服了现有技术存在的不足,提供了一种计算声屏障防水/尘孔径的方法,从根本上解决了声屏障防水、防尘的问题,本发明通过理论计算,在孔径大于0.1mm即可保证雨滴即使在暴雨时也无法通过圆孔,较大孔径只能够在小雨和风速较低的情况下保证雨滴无法破碎铺展,相反0.5mm以上的孔径会增大雨滴直接通过小孔的概率,综上所述加工0.3mm的孔即可,从根本上解决了声屏障防水、防尘的问题；本发明可广泛应用于声屏障领域。(The invention relates to a method for calculating the waterproof/dust aperture of a sound barrier, which belongs to the technical field of sound barriers, overcomes the defects in the prior art, provides a method for calculating the waterproof/dust aperture of the sound barrier, and fundamentally solves the waterproof and dust-proof problems of the sound barrier, through theoretical calculation, raindrops can be ensured to not pass through a round hole even in heavy rain when the aperture is larger than 0.1mm, the raindrops can be ensured to be not broken and spread only in light rain and at low wind speed when the aperture is larger than 0.5mm, on the contrary, the probability that the raindrops directly pass through the small hole can be increased when the aperture is larger than 0.5mm, and in conclusion, the waterproof and dust-proof problems of the sound barrier can be fundamentally solved by processing the 0.3mm hole; the invention can be widely applied to the field of sound barriers.)
1. A method of calculating the water/dust aperture of a sound barrier, characterised in that the surface tension of the water is 7.2 x 10 at an ambient temperature of 25 DEG C-2N·m-1Different levels of wind can make the raindrop produce different level impact velocity, and different rainfall levels produce the raindrop that the quality differs, and both influence the momentum when the raindrop strikes the drill way jointly, and it is about 0.01s to establish the time that the raindrop falls to zero and spreads to the sound barrier face from striking the drill way to speed, and then whether the raindrop can break through the impact force size computational formula of surface tension restraint to the drill way striking in-process as follows:
I＝mv＝Ft
the impact force F is given by the formula:
due to the fact that the raindrops exist in a spherical shape due to the surface tension, the raindrops splashed on the plate generate pressure at the orifice under the action of gravity, and the pressure is calculated according to the formula:
p＝ρgh
Wherein rho is the density of rainwater, g is the acceleration of gravity, and h is the height from the bottom of the liquid drop to the orifice.
When raindrops can break through the surface tension constraint, the raindrops flow into the hole under the action of the speed of splashing to the hole opening and the pressure, and finally the raindrops stop flowing under the on-way resistance of the circular tube.
When raindrops splash to the hole, the raindrops flow into the hole from the condition of breaking through surface tension constraint to the condition of stopping flowing, the time for spreading to the surface of the sound barrier is set to be 0.01s, and the rainwater flows in the hole within 0.01s according to a small hole flow formula as follows:
in the formula:
mu is a flow coefficient and is determined by the shape of the orifice;
a is the cross section of the orifice;
delta p is the pressure difference between the two ends of the hole, and the pressure difference between the inside and the outside of the raindrop is obtained at the moment;
ρ is the density of rainwater.
The flow rate is the flow rate of raindrops flowing into the hole within 0.01s, the speed of rainwater after 0.01s is zero and does not flow any more, the flow rate and the flowing time t are multiplied by 0.01 to obtain the volume V of the rainwater flowing into the hole, and the distance length l of the rainwater passing hole is obtained by dividing the volume V by the sectional area A of the hole, and the formula is expressed as follows:
lambda is an on-way resistance coefficient, and the magnitude of lambda is 0.1;
therefore, after the raindrops break through the surface tension constraint, the distance of the circular holes is only related to the internal and external pressure difference of the raindrops;
substituting the wind speed and the rainfall into the formula to respectively obtain:
the wind speed and rainfall impact force summary table is as follows:
General table of permeation, table below:
From the above calculations it can be found that:
the hole length is greater than 0.1mm and can guarantee that the raindrop also can't pass through the round hole even when rainstorm, and the unable broken probability of spreading of raindrop can only be guaranteed to the great aperture under the lower condition of light rain and wind speed, and the aperture more than 0.5mm can increase the raindrop and directly pass through the aperture probability on the contrary, consequently, when sound barrier aperture is 0.1mm ~ 0.5mm, can realize waterproof/dirt.
2. A method of calculating the water/dust barrier pore size according to claim 1, wherein the water/dust barrier is realized with a pore size of 0.3 mm.
Technical Field
The invention discloses a method for calculating the waterproof/dust aperture of a sound barrier, and belongs to the technical field of sound barriers.
Background
At present, sound barriers have various structures, but the waterproof and dustproof problems of the sound barriers cannot be solved all the time while sound shielding is improved, and how to fundamentally solve the technical problem is always the focus of research of technical personnel in the field.
Disclosure of Invention
The invention overcomes the defects in the prior art, provides a method for calculating the waterproof/dust aperture of the sound barrier, and fundamentally solves the problems of water resistance and dust prevention of the sound barrier.
In order to solve the technical problems, the invention adopts the technical scheme that: a method for calculating the water/dust-proof aperture of a sound barrier, the surface tension of water being 7.2 x 10 at 25 deg.C-2N·m-1Different levels of wind force will cause raindrops to produce different levelsThe impact speed, the raindrops with different quality are produced by different rainfall levels, the raindrops and the raindrops jointly influence the momentum when the raindrops impact the orifice, and the time from the impact of the raindrops to the orifice to the speed reduction to zero spreading to the surface of the sound barrier is about 0.01s, so that the calculation formula of the impact force for judging whether the raindrops break through the surface tension constraint in the orifice impact process is as follows:
I＝mv＝Ft
the impact force F is given by the formula:
due to the fact that the raindrops exist in a spherical shape due to the surface tension, the raindrops splashed on the plate generate pressure at the orifice under the action of gravity, and the pressure is calculated according to the formula:
p＝ρgh
light rain
Medium rain
Heavy rain
Heavy Rain
p(Pa)
4.9
10.41
20.82
28.18
Wherein rho is the density of rainwater, g is the acceleration of gravity, and h is the height from the bottom of the liquid drop to the orifice.
When raindrops can break through the surface tension constraint, the raindrops flow into the hole under the action of the speed of splashing to the hole opening and the pressure, and finally the raindrops stop flowing under the on-way resistance of the circular tube.
When raindrops splash to the hole, the raindrops flow into the hole from the condition of breaking through surface tension constraint to the condition of stopping flowing, the time for spreading to the surface of the sound barrier is set to be 0.01s, and the rainwater flows in the hole within 0.01s according to a small hole flow formula as follows:
in the formula:
mu is a flow coefficient and is determined by the shape of the orifice;
a is the cross section of the orifice;
delta p is the pressure difference between the two ends of the hole, and the pressure difference between the inside and the outside of the raindrop is obtained at the moment;
ρ is the density of rainwater.
The flow rate is the flow rate of raindrops flowing into the hole within 0.01s, the speed of rainwater after 0.01s is zero and does not flow any more, the flow rate and the flowing time t are multiplied by 0.01 to obtain the volume V of the rainwater flowing into the hole, and the distance length l of the rainwater passing hole is obtained by dividing the volume V by the sectional area A of the hole, and the formula is expressed as follows:
lambda is an on-way resistance coefficient, and the magnitude of lambda is 0.1;
therefore, after the raindrops break through the surface tension constraint, the distance of the circular holes is only related to the internal and external pressure difference of the raindrops;
substituting the wind speed and the rainfall into the formula to respectively obtain:
the wind speed and rainfall impact force summary table is as follows:
general table of permeation, table below:
light rain
Medium rain
Heavy rain
Heavy Rain
l(mm)
0.0614
0.0624
0.0895
0.1041
From the above calculations it can be found that:
the hole length is greater than 0.1mm and can guarantee that the raindrop also can't pass through the round hole even when rainstorm, and the unable broken probability of spreading of raindrop can only be guaranteed to the great aperture under the lower condition of light rain and wind speed, and the aperture more than 0.5mm can increase the raindrop and directly pass through the aperture probability on the contrary, consequently, when sound barrier aperture is 0.1mm ~ 0.5mm, can realize waterproof/dirt.
Preferably, the sound barrier is waterproof/dust proof with a pore size of 0.3 mm.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, through theoretical calculation, the raindrops can be ensured to not pass through the round holes even in heavy rain when the aperture is larger than 0.1mm, the raindrops can be ensured not to be broken and spread only under the conditions of light rain and low wind speed when the aperture is larger than the aperture, and on the contrary, the probability that the raindrops directly pass through the small holes can be increased by the aperture of more than 0.5mm, so that the problem of water and dust prevention of the sound barrier can be fundamentally solved by processing the aperture of 0.3 mm.
Drawings
The invention is further described below with reference to the accompanying drawings.
FIG. 1 is a schematic structural diagram of the present invention.
Detailed Description
As shown in fig. 1, in the method for calculating the waterproof/dust aperture of the sound barrier according to the present invention, when raindrops fall from high altitude, the raindrops fall at a certain angle θ with the vertical line under the action of gravity and wind force until the raindrops splash onto the sound barrier panel.
When raindrops splash onto the sound barrier plate, the impact effect on the small holes on the sound barrier plate is only the component generated by wind power, and if the instantaneous pressure when the raindrops splash onto the small holes on the sound barrier plate is greater than the surface tension of the raindrops at the orifices, the raindrops can break and spread at the orifices, and then seepage flows into the orifices.
The surface tension of water is 7.2X 10 at 25 deg.C-2N·m-1Different levels of wind can make the raindrop produce different level impact velocity, and different rainfall levels produce the raindrop that the quality differs, and both influence the momentum when the raindrop strikes the drill way jointly, and it is about 0.01s to establish the time that the raindrop falls to zero and spreads to the sound barrier face from striking the drill way to speed, and then whether the raindrop can break through the impact force size computational formula of surface tension restraint to the drill way striking in-process as follows:
I＝mv＝Ft
the impact force F is given by the formula:
different pore sizes produce different surface tensions as shown in the following table, too large pore sizes will cause raindrops to directly pass through the pores of the plate, and too small pore sizes will cause higher processing difficulty, so that the following table only lists a few representative pore sizes.
Due to the fact that the raindrops exist in a spherical shape due to the surface tension, the raindrops splashed on the plate generate pressure at the orifice under the action of gravity, and the pressure is calculated according to the formula:
p＝ρgh
light rain
Medium rain
Heavy rain
Heavy Rain
p(Pa)
4.9
10.41
20.82
28.18
Wherein rho is the density of rainwater, g is the acceleration of gravity, and h is the height from the bottom of the liquid drop to the orifice.
When raindrops can break through the surface tension constraint, the raindrops flow into the hole under the action of the speed of splashing to the hole opening and the pressure, and finally the raindrops stop flowing under the on-way resistance of the circular tube.
When raindrops splash to the hole, the raindrops flow into the hole from the condition of breaking through surface tension constraint to the condition of stopping flowing, the time for spreading to the surface of the sound barrier is set to be 0.01s, and the rainwater flows in the hole within 0.01s according to a small hole flow formula as follows:
in the formula:
mu is a flow coefficient and is determined by the shape of the orifice;
a is the cross section of the orifice;
delta p is the pressure difference between the two ends of the hole, and the pressure difference between the inside and the outside of the raindrop is obtained at the moment;
ρ is the density of rainwater.
The flow rate is the flow rate of raindrops flowing into the hole within 0.01s, the speed of rainwater after 0.01s is zero and does not flow any more, the flow rate and the flowing time t are multiplied by 0.01 to obtain the volume V of the rainwater flowing into the hole, and the distance length l of the rainwater passing hole is obtained by dividing the volume V by the sectional area A of the hole, and the formula is expressed as follows:
lambda is an on-way resistance coefficient, and the magnitude of lambda is 0.1;
according to the formula, after the raindrops break through the surface tension constraint, the distance of the circular holes is only related to the pressure difference between the inside and the outside of the raindrops. The wind ratings available from national standards are shown in the following table:
raindrop quality is related to its own size, which is related to the rainfall level, and is divided as follows:
wind speed and rainfall impact force general meter
Summary of permeation events
Light rain
Medium rain
Heavy rain
Heavy Rain
l(mm)
0.0614
0.0624
0.0895
0.1041
The hole length obtained by the calculation is larger than 0.1mm, so that raindrops can be ensured to pass through the round hole even in heavy rain, the larger hole diameter can only ensure that the raindrops can not be broken and spread under the conditions of light rain and low wind speed, and on the contrary, the hole diameter of more than 0.5mm can increase the probability that the raindrops directly pass through the small hole, so that the 0.3mm hole is processed.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.