CN108253524A - Double polygon prisms imitate dynamic natural wind generator - Google Patents

Abstract

The invention provides a double multi-prism imitation dynamic natural wind generator, comprising a rectangular air duct, the end of the rectangular air duct is provided with a rectangular air supply port, and a Karman vortex street generator is arranged in the rectangular air supply port; the Karman vortex street generator is Two polygonal columns, the two polygonal columns are both perpendicular to the long side of the rectangular air supply port. In the building space of the present invention, the air treated by the air conditioning system is sent to the end of the system through the air supply pipe, that is, the rectangular tuyere, and then passes through the Karman vortex generator, and when the steady flow bypasses the Karman vortex generator, The two sides of the Karman vortex street generator will periodically shed out the dicolumn vortex with opposite rotation direction and regular arrangement, and form Karman vortex street after nonlinear action. Increase the turbulence of the air flow, increase the turbulence intensity, increase the speed fluctuation, and eliminate the monotony of mechanical air supply.

Description

Double polygon imitation dynamic natural wind generator

technical field

The invention belongs to the technical field of heating, ventilating and air-conditioning, and in particular relates to a multi-prism imitation dynamic natural wind generator.

Background technique

At present, the air supply method in the building space is mostly mixed ventilation based on the dilution principle; the traditional mixed ventilation system air supply outlet is usually installed on the top of the room or in the middle of the side wall. The air supply air enters the air-conditioned room in the form of a free jet. The free jet is characterized by high speed, large momentum and turbulent air supply. Because the air supply port is easy to arrange in the building space, it does not occupy the lower building space (working area), and the free jet mixes Ventilation is still widely used today. The most common orifice free jet configuration is shown in Figure 1. The air supply method is the main factor affecting the thermal comfort of the human body. A reasonable air supply method can not only improve people's comfort of blowing, but also increase the upper limit of the human body's thermal comfort temperature and reduce the energy consumption of air conditioning. Therefore, the comfort of the human body can be satisfied by imitating the natural wind, the indoor air-conditioning equipment can be improved, and the humanized design of the air-conditioning equipment can be promoted. Air supply is one of the main factors that change the indoor thermal environment and affect the thermal comfort of the human body. The air flow formed by different air supply methods has great differences in velocity distribution, turbulence intensity, and spectral characteristics. The drying experience is also very different. Compared with the monotonous mechanical wind, the natural wind is generally loved by people for its fresh, soft, changeable and comfortable dynamic airflow. Dynamic and comfortable airflow is an important direction to improve the thermal environment of buildings.

Karman vortex street is an important phenomenon in fluid mechanics and can often be encountered in nature. When the fluid bypasses the bluff object, the paired, alternately arranged, antisymmetric vortices with opposite rotation directions are generated on the left and right sides of the wake of the object. The jet flow result is shown in Figure 2. Karman vortex street is a phenomenon studied in viscous incompressible fluid dynamics. Karman vortex street will be generated when fluid flows around tall chimneys, high-rise buildings, wires, oil pipelines and tube bundles of heat exchangers. In 1911, the German scientist von Karman found the theoretical basis for this vortex stability from the perspective of aerodynamics. However, the use of the periodic and alternating nature of the Karman vortex street makes the Karman vortex street have some very important applications. For example, it can be made into a Karman vortex flowmeter, which can determine the velocity or flow of the fluid by measuring the shedding frequency of the vortex. . The patent of this invention uses the principle of Karman vortex street to invent a new type of air outlet at the end of the air conditioning system, which can send out a dynamic airflow similar to natural wind, making the traditional mechanical air supply jet closer to natural wind and improving people's blowing experience .

Contents of the invention

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a multi-prism imitation dynamic natural wind generator, which solves the problem in the prior art that the air output of the indoor air conditioner is not soft enough, varied and comfortable.

In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve:

A double multi-prism imitation dynamic natural wind generator, comprising a rectangular air duct, the end of the rectangular air duct is provided with a rectangular air supply port, and a Karman vortex street generator is arranged in the rectangular air supply port; the Karman vortex street generator The device is two polygonal prisms, both of which are perpendicular to the long sides of the rectangular air supply port.

Further, guide rails are provided on the two opposite long side inner walls of the rectangular air supply port, and the two ends of the Karman vortex generator are respectively arranged in the guide rails, and can move left and right along the guide rails.

Further, it also includes a control mechanism for adjusting the left and right movement frequency of the Karman vortex generator in the guide rail.

Further, the frequency at which the Karman vortex street generator moves left and right in the guide rail is 6 times/min to 15 times/min.

Further, the outer edge of the Karman vortex street generator is flush with the outer edge of the rectangular air supply port.

Further, the polygonal prisms may be 3 prisms or 5-9 prisms.

Further, when the polygonal prisms are 5-9 prisms, the ratio of the perimeter length of the polygonal prisms to the length of the long side of the rectangular air supply port is 0.25-0.70.

Further, when the polygonal prism is a triangular prism, the ratio of the circumference of the polygonal prism to the length of the long side of the rectangular air outlet is 0.06-0.19.

Further, the material of the polygonal columns is wood, plastic or metal.

Compared with the prior art, the present invention has the following technical effects:

The present invention adopts integrated structure, simple structure, convenient installation and disassembly. In the building space, the air treated by the air conditioning system is sent to the end of the system through the air supply pipe, that is, the rectangular air outlet, and then passes through the Karman vortex generator. When the steady flow bypasses the Karman vortex generator, the Karman vortex Both sides of the street generator will periodically fall out of the dicolumn vortex with opposite rotation direction and regular arrangement, and form a Karman vortex street after nonlinear action. Increase the turbulent flow of the airflow, increase the turbulent flow intensity, increase the speed fluctuation, and eliminate the monotony of mechanical air supply. In addition, due to the increased turbulence intensity, the convective heat transfer between the human body and the environment increases, thus enhancing the cooling effect of the airflow and making people feel more comfortable.

Description of drawings

Fig. 1 is a schematic diagram of a circular orifice free jet structure;

Figure 2 is a schematic diagram of the Karman vortex street;

Fig. 3 is a structural schematic diagram of a double polygonal prism imitating dynamic natural wind generator of the present invention under an embodiment;

Fig. 4 is a schematic diagram of the structure of the double polygonal prism imitating dynamic natural wind generator of the present invention under an embodiment;

Fig. 5 (a) is the histogram of double pentagonal wind speed probability distribution during mechanical wind of the present invention;

Figure 5(b) is a histogram of the probability distribution of the wind speed of the double pentagonal prism when the perimeter of the Karman vortex street generator is 80mm;

Figure 5(c) is a histogram of the probability distribution of the double pentagonal wind speed when the perimeter of the Karman vortex street generator is 225mm;

Fig. 6 (a) is the histogram of the probability distribution of double heptagonal prism wind speed during mechanical wind of the present invention;

Figure 6(b) is a histogram of the probability distribution of the double heptagonal prism wind speed when the perimeter of the Karman vortex street generator is 80 mm;

Figure 6(c) is a histogram of the probability distribution of the double heptagonal prism wind speed when the perimeter of the Karman vortex street generator is 225mm;

Fig. 7 (a) is the histogram of the probability distribution of double nine prism wind speed during the mechanical wind of the present invention;

Figure 7(b) is a histogram of the probability distribution of the double nine prism wind speed when the perimeter of the Karman vortex street generator is 80mm;

Figure 7 (c) is a histogram of the probability distribution of the double nine prism wind speed when the perimeter of the Karman vortex street generator is 225mm;

Fig. 8 (a) is the cloud diagram of the turbulence intensity of the double pentagonal prism when the perimeter of the single polygonal prism Karman vortex street generator and the long side ratio of the rectangular tuyeres are 0.25;

Fig. 8 (b) is the speed contour diagram of the double pentagonal prism when the ratio of the perimeter of the single polygonal prism Karman vortex street generator to the long side of the rectangular tuyere is 0.25 in the present invention

Fig. 9 (a) is the cloud map of the turbulence intensity of the double heptagonal prism when the perimeter of the single multi-prism Karman vortex street generator and the long side ratio of the rectangular tuyere are 0.25;

Fig. 9 (b) is the speed contour diagram of the double heptagonal prism when the perimeter of the single polygonal prism Karman vortex street generator and the long side ratio of the rectangular tuyere are 0.25 in the present invention

Fig. 10 (a) is the turbulence intensity nephogram of double nine prisms when the perimeter of a single polygonal prism Karman vortex street generator and the long side ratio of a rectangular tuyere are 0.25 in the present invention;

Fig. 10 (b) is the speed contour diagram of double nine prisms when the ratio of the perimeter of a single polygonal prism Karman vortex street generator to the long side of a rectangular tuyere is 0.25 in the present invention

Fig. 11 (a) is the turbulence intensity cloud map of the double pentagonal prism when the perimeter of the single polygonal prism Karman vortex street generator and the long side ratio of the rectangular tuyeres are 0.70 in the present invention;

Fig. 11 (b) is the speed contour diagram of the double pentagonal prism when the ratio of the perimeter of the single polygonal prism Karman vortex street generator to the long side of the rectangular tuyere is 0.70 in the present invention

Fig. 12 (a) is the turbulence intensity cloud map of the double heptagonal prism when the perimeter of the single polygonal prism Karman vortex street generator and the long side ratio of the rectangular tuyere are 0.70;

Fig. 12 (b) is the speed contour diagram of the double heptagonal prism when the ratio of the perimeter of the single polygonal prism Karman vortex street generator to the long side of the rectangular tuyere is 0.70 in the present invention

Fig. 13 (a) is the turbulence intensity nephogram of double nine prisms when the ratio of the perimeter of a single multi-prism Karman vortex street generator to the long side of a rectangular tuyere is 0.70;

Fig. 13 (b) is the speed contour diagram of double nine prisms when the perimeter of a single polygonal prism Karman vortex street generator and the long side ratio of a rectangular tuyere are 0.70;

Fig. 14 (a) is the histogram of the probability distribution of wind speed during mechanical wind of the present invention;

Fig. 14 (b) is the histogram of the probability distribution of wind speed when the edge of the Karman vortex street generator gets 20mm toward the outer side of the air duct in the present invention;

Fig. 14 (c) is the histogram of the wind speed probability distribution when the edge of the Karman vortex street generator gets 60mm toward the outer side of the air duct in the present invention;

Fig. 15 (a) is the turbulence intensity nephogram when the ratio of the edge length of a single triangular prism Karman vortex street generator towards the outside of the air duct to the long side of the rectangular tuyere is 0.19;

Fig. 15 (b) is the speed contour diagram when the single triangular prism Karman vortex street generator edge is towards the outside side length of the air duct and the ratio of the long side of the rectangular tuyere is 0.06 in the present invention;

The meanings of each label in the figure are: 1-rectangular air duct, 2-rectangular air supply port, 3-Karman vortex generator, 4-control mechanism.

The specific content of the present invention will be further explained in detail below in conjunction with the accompanying drawings.

Detailed ways

It should be noted that as shown in Fig. 3 and Fig. 4, the two long sides of the rectangular air supply port 2 in this application refer to the top and bottom sides in the figure, and the left and right in this application refer to the air supply along the rectangular shape. The two directions in which the long side of the tuyere extends.

In the building space, the air treated by the air conditioning system is sent to the end of the system through the air supply pipe, that is, the rectangular air outlet 2, and then passes through the Karman vortex street generator 3, and the steady incoming flow bypasses the Karman vortex street generator 3 , the two sides of the Karman vortex street generator 3 will periodically shed out the dicolumn vortices with opposite rotation directions and regular arrangement, and form a Karman vortex street after nonlinear action. Increase the turbulent flow of the airflow, increase the turbulent flow intensity, increase the speed fluctuation, and eliminate the monotony of mechanical air supply.

Specific embodiments of the present invention are provided below, and it should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations done on the basis of the technical solutions of the present application all fall within the scope of protection of the present invention.

Example:

According to the above-mentioned technical scheme, as shown in Fig. 3 to Fig. 4, this embodiment provides a double polygonal prism imitation dynamic natural wind generator, including a rectangular air duct 1, and the end of the rectangular air duct 1 is provided with a rectangular air supply port 2, A Karman vortex street generator 3 is arranged in the rectangular air supply port 2 . In this embodiment, the vortex air flow produced by the Karman vortex street generator is used to simulate the soft, changeable and comfortable blowing experience of natural wind. This air supply device can not only improve people's blowing experience, but also increase the upper limit of the thermal comfort temperature of the human body and reduce the energy consumption of the air conditioner. It is also helpful to improve indoor air-conditioning equipment, promote the humanized design of air-conditioning equipment, and improve the quality of indoor temperature environment.

The Karman vortex street generator 3 in the present embodiment is two multi-prisms, and two multi-prisms are all perpendicular to the long side of rectangular air supply port 2, and multi-prisms can be 3 prisms or 5 prisms～9 prisms, and the material of multi-prisms is Wood, plastic or metal.

When the polygonal prism is 5-9 prisms, the ratio of the perimeter of the polygonal prism to the length of the rectangular air supply port 2 is 0.25-0.70. When the ratio is less than 0.25, the Karman vortex street phenomenon is not obvious, and the effect of imitating natural wind is not obvious. Well, when the ratio is greater than 0.70, on the one hand, the Karman vortex street phenomenon is not obvious, on the other hand, it will affect the air supply volume of the air duct.

When the polygonal prism is a triangular prism, the ratio of the diameter of the triangular prism to the length of the long side of the rectangular air supply port 2 is 0.25 to 0.70. When the ratio is less than 0.25, the Karman vortex street phenomenon is not obvious, and the effect of imitating natural wind is not good. When the ratio When it is greater than 0.70, on the one hand, the Karman vortex street phenomenon is not obvious, on the other hand, it will affect the air supply volume of the air duct.

In this embodiment, guide rails are provided on the inner walls of the two opposite long sides of the rectangular air supply port 2, and the two ends of the Karman vortex generator 3 are respectively arranged in the guide rails, and can move left and right along the guide rails. Like this, by moving the Karman vortex street generator 3 left and right, the wind sent by the rectangular air supply port 2 can realize left and right sweeping, and can not only concentrate on one point of blowing, and the human body feels more comfortable. In order to be more intelligent, the present embodiment also includes a control mechanism 4 for adjusting the frequency of Karman vortex generator 3 moving left and right in the guide rail, which can control the frequency of Karman vortex generator 3 moving left and right in the guide rail to be 6 times/ min～15 times/min.

In this embodiment, in order to verify the air outlet characteristics of the double polygonal prism imitation dynamic natural wind generator, the following two embodiments have been mentioned:

Example 1:

When the multi-prisms are 5-6 prisms, the length × width × height of the room is 10 × 8 × 6m, the size of the end of the rectangular air duct is 320mm × 250mm; the air supply speed is 4m/s; the height of the rectangular air outlet from the ground is 4800mm; The number of rectangular air outlets is 4; the perimeters of the prisms of the Karman vortex street generator are respectively 800mm and 225mm; there are 2 return air outlets, and the size is 400×200mm.

In this embodiment, the κ-ε double-equation model is used for simulation calculation. The control equation is based on the above assumptions, and the time-average control equation of the κ-ε turbulence mathematical model is obtained, which is expressed in tensor form. The governing equations are established as follows:

Continuity equation:

Momentum equation:

Energy equation:

Where: i=1,2,2; j=1,2,3; u is indoor air velocity; k is turbulent pulsating kinetic energy; T is indoor air temperature; μ is laminar dynamic viscosity; μ _t is turbulent dynamic viscosity coefficient ; p is the air pressure; ρ is the air density; C _p is the constant pressure specific heat capacity; q is the heat flux density; _β is the fluid volume expansion coefficient; _c is the smoke concentration; _r is the Prandtl number.

The degree of fluctuation of airflow velocity can be expressed by the intensity of turbulence. Turbulence intensity is defined as the ratio of the standard deviation of velocity fluctuations to the average velocity, which indicates the level of wind velocity fluctuations in a certain period of time.

The natural wind caused by atmospheric circulation is mostly in a turbulent state, and the movement form of its airflow is extremely unstable.

Take five points on the central axis of the air duct that are 200mm, 400mm, 600mm, 800mm, and 1000mm from the air outlet, and record A1, A2, A3, A4, and A5. The simulation was carried out using Fluent software. When the girth of the Karman vortex street generator (3) is 80mm and 225mm, that is, the ratio of the girth of the Karman vortex street generator to the long side of the rectangular tuyere is 0.25 and 0.70, the imitation natural wind and mechanical wind of the five prisms, the heptagonal prisms and the nine prisms (That is, no Karman vortex generator is added at the end of the air supply duct.) The turbulence intensity simulation results are shown in Table 1, and the velocity results of each group are shown in Figures 5-7.

Table 1 Turbulence intensity at each point when the perimeter of the Karman vortex street generator is taken as 80mm and 225mm

Example 2:

When the polygonal prism is a triangular prism, the room length × width × height of this embodiment is 10 × 8 × 6m; the size of the end air duct is 320mm × 250mm; the air outlet speed is 4m/s; the height of the rectangular air outlet from the ground is 4800mm; The number of air outlets is 4; the side lengths of the Karman vortex street generator are respectively taken as 20mm and 60mm; there are 2 return air outlets, and the size is 400×200mm.

In order to verify the air outlet characteristics of the double triangular prism imitation dynamic natural wind generator, the gas flow in the simulated building space is regarded as an incompressible fluid; at the same time, the air temperature does not change much, that is, the density does not change much, so it can be considered as an indoor The air flow conforms to the Boussinesq assumption. For this purpose, the κ-ε double-equation model is used for simulation calculation. The control equation is based on the above assumptions, and the time-average control equation of the κ-ε turbulent mathematical model is obtained, which is expressed in tensor form. The governing equations are established as follows:

Continuity equation:

Momentum equation:

Energy equation:

Where: i=1,2,2; j=1,2,3; u is indoor air velocity; k is turbulent pulsating kinetic energy; T is indoor air temperature; μ is laminar dynamic viscosity; μ _t is turbulent dynamic viscosity coefficient ; p is the air pressure; ρ is the air density; C _p is the constant pressure specific heat capacity; q is the heat flux density; _β is the fluid volume expansion coefficient; _c is the smoke concentration; _r is the Prandtl number.

The degree of fluctuation of airflow velocity can be expressed by the intensity of turbulence. Turbulence intensity is defined as the ratio of the standard deviation of velocity fluctuations to the average velocity, which indicates the level of wind velocity fluctuations in a certain period of time.

The natural wind caused by atmospheric circulation is mostly in a turbulent state, and the movement form of its airflow is extremely unstable.

Take five points on the central axis of the air duct that are 200mm, 400mm, 600mm, 800mm, and 1000mm from the air outlet, and record A1, A2, A3, A4, and A5 as the points where the edge of the triangular prism faces the outside of the air duct; record B1, B2, B3, B4, and B5 are the points where the edge of the triangular prism faces the outside of the air duct. Use Fluent software to simulate; when the diameter of the Karman vortex street generator (3) is 20mm, 60mm, that is, the ratio of the side length of the Karman vortex street generator to the long side of the rectangular tuyere is 0.06, 0.19, the imitation of natural wind and mechanical wind (i.e. air supply) The simulation results of turbulent flow intensity without adding Karman vortex generator at the end of the pipeline are shown in Table 2, and the velocity results of each group are shown in Figures 14-15.

Table 2 Turbulence intensity at each point when the side length of the Karman vortex street generator is 20mm and 60mm

Through simulation, compared with the wind speed change of the mechanical wind sent by the traditional rectangular tuyere, the speed fluctuation of the simulated natural wind sent by the double multi-prism dynamic natural wind generator is larger, and the turbulence intensity of the simulated natural wind is also greater than that of the mechanical wind turbulence intensity. This will make people feel the airflow fluctuation imitating natural wind. The fluctuating airflow imitating the natural wind can make people feel natural, fresh and comfortable. Reduced the monotony of mechanical wind blowing. On the other hand, the turbulence intensity of the imitation natural wind sent by the double polygon imitation dynamic natural wind generator is relatively large, which increases the convective heat exchange between the human body and the environment, thereby enhancing the cooling effect of the airflow. The influence of the turbulence intensity of the airflow on the cooling effect is obvious, but the influence of the turbulence intensity on the thermal comfort of the human body should also be noticed. When the turbulence is too high, the strong gusts caused by excessive airflow fluctuations can cause human discomfort.

In addition, compared with the traditional mechanical wind, the speed of the imitation natural wind varies greatly, and it is random and uncertain. According to the current research, the speed distribution of the mechanical wind is a relatively regular normal distribution, but the speed distribution of the imitation natural wind sent by the double multi-prism imitation dynamic natural wind generator is not a normal distribution of complete random variables, but Due to the indirect influence of turbulence, the velocity distribution deviates from the normal distribution. The simulated natural wind with skewed distribution of wind speed is more acceptable than the mechanical wind with normal distribution. This is mainly because the skewed airflow makes people feel the fluctuating wind speed more easily, and the low wind speed takes longer to act, which also reduces the fatigue of blowing.

Claims (9)

1. a kind of dynamic natural wind generator imitating two multi-prisms is characterized in that, comprises rectangular air duct (1), and the end of described rectangular air duct (1) is provided with rectangular air supply port (2), and described rectangular air supply port (2) is provided with a Karman vortex generator (3); the Karman vortex generator (3) is two polygonal prisms, and the two polygonal prisms are perpendicular to the long side of the rectangular air supply port (2). 2. double polygonal prism imitation dynamic natural wind generator according to claim 1, is characterized in that, two relative long side inner walls of described rectangular air supply port (2) are provided with guide rail, and Karman vortex street generator (3 ) are respectively arranged in the guide rail, and can move left and right along the guide rail. 3. The double polygonal prism imitation dynamic natural wind generator according to claim 2, is characterized in that, also comprises the control mechanism (4) that is used for adjusting the left and right movement frequency of Karman vortex street generator (3) in guide rail. 4. double multi-prism imitation dynamic natural wind generator according to claim 3, is characterized in that, the frequency that described Karman vortex street generator (3) moves left and right in guide rail is 6 times/min～15 times/min . 5. The double polygonal prism imitation dynamic natural wind generator according to claim 1, characterized in that, the outer edge of the Karman vortex street generator (3) is flush with the outer edge of the rectangular air supply port (2). 6. The dynamic natural wind generator with double polygonal prisms according to claim 1, characterized in that, the polygonal prisms can be 3 prisms or 5-9 prisms. 7. The imitation dynamic natural wind generator with double polygonal prisms according to claim 6 is characterized in that, when the polygonal prisms are 5 to 9 prisms, the perimeter of the polygonal prisms is as long as the rectangular air supply port (2) The ratio of side to side length is 0.25 to 0.70. 8. double multi-prism imitation dynamic natural wind generator according to claim 6, is characterized in that, when described multi-prism is 3 prisms, the perimeter of described multi-prism and rectangular air supply port (2) long side The long ratio is 0.06-0.19. 9. The double polygonal prism imitating dynamic natural wind generator according to claim 1, characterized in that, the material of the polygonal prism is wood, plastic or metal.