CN209878799U - Snow particle settling velocity measuring device - Google Patents

Abstract

The utility model provides a settling velocity measuring device for snow particles, which belongs to the technical field of disaster prevention, and comprises a cylinder stable section, a cylinder test section and an anemometer. The two ends of the cylinder stable section are open and the bottom end is fixed with a fan. , the stable section of the cylinder is also provided with a rectification mechanism for rectifying the airflow blown by the fan and a filter screen for placing snow particles, the rectification mechanism is arranged above the top of the fan at intervals, and the filter screen is arranged at intervals on the top of the rectification mechanism above; the two ends of the test section of the cylinder are open, set on the upper end of the stable section of the cylinder and detachably connected with the stable section of the cylinder; the anemometer is used to measure the wind speed at the end of the test section of the cylinder away from the stable section of the cylinder. The snow particle sedimentation velocity measurement device provided by the utility model can be placed in the external natural environment, and the same environmental conditions can be easily achieved. The various property parameters of the snow are not easily changed by the influence of the external environment. The device has a simple structure and is easy to operate.

Description

A device for measuring the sedimentation velocity of snow particles

technical field

The utility model belongs to the technical field of sedimentation velocity measurement, in particular relates to a snow particle sedimentation velocity measurement device.

Background technique

Wind and snow flow is a natural phenomenon in which snow particles drift and accumulate under the action of wind. When the blizzard occurs, the snow accumulation in some areas is severe, causing traffic jams, building damage and other phenomena, seriously affecting people's daily life. As the material source of snowstorms, the properties of snow have an important impact on the process of starting, drifting, and accumulation of snowstorms. The sedimentation velocity of snow is one of the important property parameters of snow. The settling velocity of snow refers to the velocity of snow particles settling at a constant velocity in still air. The maximum speed achieved.

In order to measure the sedimentation velocity of particulate matter, there are mainly two methods commonly used at present: 1. Test at a given time, measure the vertical distance passed by the particulate matter within a certain time interval; 2. Test at a given distance, measure and record the sedimentation process of particulate matter The time required for a fixed distance. Through the ratio of the particle settling distance to the settling time, a velocity of the particle is obtained, and the average value of multiple measurements is obtained to obtain the average settling velocity of the particle in the flowing medium. These two methods use cameras, computers, video recorders and other technical equipment to record and obtain experimental data during the measurement process. The working environment of such technical equipment has relatively large restrictions, and it cannot work normally in a cold and strong wind environment. Moreover, snow particles are different from ordinary particles. The properties and parameters of snow particles are greatly affected by the natural environment in which they are located. Factors such as temperature and humidity can significantly change the parameters such as snow particle size and sedimentation velocity. The property parameters of the snow can represent the property parameters of the snow in the real state.

Utility model content

The purpose of this utility model is to provide a snow particle sedimentation velocity measurement device, aiming to solve the problem that the environment has a great influence on the snow particles due to the limitation of the technical equipment in the measurement process and the temperature and humidity factors.

In order to achieve the above purpose, the technical solution adopted by the utility model is: provide a snow particle sedimentation velocity measurement device, including: cylinder stable section, cylinder test section and anemometer, the two ends of the cylinder stable section are open and the bottom A fan is fixed at the end, and a rectification mechanism for rectifying the airflow blown by the fan and a filter screen for placing snow particles are also provided in the stable section of the cylinder, and the rectification mechanism is arranged at intervals on the fan Above the top, the filter screen is arranged above the top of the rectifying mechanism at intervals; the two ends of the cylinder test section are open, arranged on the upper end of the cylinder stable section and detachable from the cylinder stable section Connection; the anemometer is used to measure the wind speed at the end of the test section of the cylinder away from the stable section of the cylinder.

Further, the rectifying mechanism includes a honeycomb.

Further, the rectification mechanism further includes a damping net, and the damping net is arranged above the honeycomb.

Further, the length of the stable section of the cylinder is 1.25-1.75 times the cross-sectional diameter of the stable section of the cylinder.

Further, the length of the stable section of the cylinder is 175mm, the diameter of the stable section of the cylinder is 100mm, and the length of the rectification mechanism is 60mm.

Further, the snow particle settling velocity measurement device also includes a snow collecting bucket, the two ends of the snow collecting bucket are open and the cross-sectional area in the horizontal direction increases sequentially from the bottom end to the top end, and the bottom end is outside the stable section of the cylinder. The surface is detachably attached to collect snow particles after the measurement is complete.

Further, the device for measuring the settling velocity of snow particles also includes a bracket, which is used to support the stable section of the cylinder.

Further, the anemometer is a hot wire anemometer.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the utility model, the following will briefly introduce the accompanying drawings that are required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only the practical For some novel embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative work.

Fig. 1 is the structural representation of the snow particle sedimentation velocity measuring device provided by the utility model embodiment;

Fig. 2 is a structural schematic diagram of a snow particle sedimentation velocity measuring device provided by another embodiment of the present invention;

Fig. 3 is a top view of the honeycomb provided by the embodiment of the present invention.

In the figure: 1, cylinder stabilization section; 2, cylinder test section; 3, fan; 4, rectification mechanism; 41, honeycomb device; 5, damping net; 6, filter screen; 7, bracket; 8, snow bucket ; 9, heat pipe.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

Please refer to Fig. 1 together, and now the snow particle sedimentation velocity measuring device provided by the utility model is described. Snow particle settling velocity measuring device, including cylinder stable section 1, cylinder test section 2 and anemometer, the two ends of cylinder stable section 1 are open and the bottom end is fixedly provided with fan 3, and cylinder stable section 2 is also equipped with There are rectifying mechanism 4 for rectifying the airflow blown by fan 3 and filter screens 6 for placing snow particles. Above; both ends of the cylinder test section 2 are open, set on the upper end of the cylinder stable section 1 and detachably connected with the cylinder stable section 1; the anemometer is used to measure the distance between the cylinder test section 2 and the cylinder stable section 1 wind speed at one end.

The snow particle sedimentation velocity measurement device provided by the utility model, compared with the prior art, the utility model snow particle sedimentation velocity measurement device is provided with a cylinder stabilization section 1, a cylinder test section 2 and an anemometer, and passes through the cylinder stabilization section 1 The fan 3 is fixedly installed at the bottom, the rectification mechanism 4 and the filter screen 6 are arranged in the stable section 1 of the cylinder, the rectification mechanism 4 and the filter screen 6 are arranged in sequence on the top of the fan 3, the fan 3 and the rectification mechanism 4, the rectification mechanism 4 and the filter screen 6 A certain distance is set between them, the cylinder stabilization section 1 is detachably connected to the cylinder test section 2, the snow particles are placed on the filter screen 6, the snow particles are kept in a stable suspension state through the adjustment of the wind speed, and the cylinder body is measured by an anemometer. The settling speed of snow particles can be obtained from the wind speed at the nozzle of the test section 2. The device of the utility model is not easily affected by the external environment and can easily achieve the same temperature and humidity when placed in the external environment.

In this embodiment, the fan 3 is a low-speed fan, and the fan 3 is glued to the inner wall of the stable section 1 of the cylinder or welded to a fixed support plate at the bottom of the inner wall of the stable section 1 of the cylinder to support the fan 3. Holes are arranged on the support plate for use To dissipate the heat generated by the fan 3 . A portable DC power supply is used to provide current to the low-speed fan. The portable DC power supply is preferably a low-temperature resistant battery, which can stably supply current to the low-speed fan in a cold external environment. The wind speed of the low-speed fan is continuously adjustable, and the airflow edge can be selected more accurately. The speed of the axial movement of the stable section 1 of the cylinder, while the stable section 1 of the cylinder is provided with an opening that can adjust the wind speed of the fan 3; The wind speed of the fan 3 in the cylinder stabilizing section 1 is adjusted, and the cylinder stabilizing section 1 is made of a steel equal-section cylinder.

The principle of the utility model is that when the snow particles are in the updraft whose flow velocity is equal to the settling velocity, the particles will be in a suspended state. At this time, the gravity, buoyancy, resistance and other forces on the snow particles reach a balance state. At this time, the speed of the updraft is called is the suspension speed. The settling velocity of snow refers to the velocity at which snow particles settle at a constant velocity in still air. Comparing the definitions of the sedimentation velocity and the suspension velocity, it can be found that the forces on the snow particles of both have reached an equilibrium state. It can be seen that the sedimentation velocity and the suspension velocity are different in meaning but equal in value. Therefore, the sedimentation velocity of the particles can be obtained by measuring the suspension velocity.

The mechanical analysis of snow particle settlement in still air, the fluid resistance of snow particles in the air can be calculated by formula (1):

In the formula: C _D — drag coefficient, which is related to parameters such as Reynolds number, Mach number and Storrowha number;

S—the cross-sectional area of snow particles in the direction of deposition;

υ—moving velocity of snow particles in the airflow;

ρ—fluid density.

The gravitational force on snow particles can be calculated by formula (2):

G= _ρn gV (2)

In the formula: ρ _n — snow particle density (kg/m ₃ );

V—volume of snow particles (m ₃ ).

The buoyancy force on snow particles can be calculated by formula (3):

F _float = ρgV (3)

When the snow particles are force-balanced in the still air, the sum of the gravity, resistance and buoyancy is 0, and the calculation formula (4) of the settling velocity υ ₀ of the snow particles in the still airflow can be obtained. At this time, the snow particles are in The velocity of motion in the airflow υ = υ ₀ .

Through the force analysis of snow particles in the vertically flowing air, it is assumed that the air inside the test device moves vertically upwards relative to the device at a uniform speed μ, and the snow particles in the flowing air move relative to the device at a speed ω. At this time, the relative velocity υ of snow particles relative to the flowing air can be calculated by formula (5).

υ＝ω+μ (5)

The calculation of the resistance, gravity and buoyancy of snow particles is consistent with the calculation method of snow particles in a static fluid. It can be obtained that the suspension velocity υ of snow particles when the force is balanced is equal to the settling velocity υ ₀ of snow particles in a static airflow. At this time, the moving speed ω of the snow particles relative to the device is the difference between the speed ν ₀ and the speed μ of the airflow relative to the measuring device. When the moving velocity μ of the airflow is equal to the settling velocity ν ₀ , the moving velocity ω of the snow particles relative to the device is 0, and at this moment, the snow particles will remain motionless in space. The settling velocity of snow particles can be obtained by reading the airflow velocity at this time.

As a specific embodiment of the snow particle settling velocity measuring device provided by the utility model, please refer to Fig. 1 and Fig. 3, the rectification mechanism 4 comprises a honeycomb 41, and the honeycomb 41 is assembled by a circular pipe, and the honeycomb 41 and The stable section 1 of the cylinder is detachably connected, preferably a threaded connection, and the exterior of the honeycomb 41 is provided with external threads, and the interior of the stable section 1 of the cylinder is correspondingly provided with internal threads; it can also be a frosted connection, and the exterior of the honeycomb 41 is set as a frosted surface. The interior of the barrel stabilization section 1 is set as a frosted surface. It is also possible to cement the honeycomb 41 and the cylinder stable section 1 . The honeycomb 41 can rectify the turbulent airflow blown by the fan 3 and reduce the turbulence of the airflow.

As a specific implementation of the utility model embodiment, please refer to Fig. 1, the rectification mechanism 4 also includes a damping net 5, the damping net 5 is arranged on the top of the honeycomb 41, and the damping net 5 and the filter net 6 are respectively stable with the cylinder Section 1 is detachably connected, and the damping net 5 and the filter net 6 are provided with curling around them, and the curling of the damping net 5 and the filter net 6 is inserted into the stable section 1 of the cylinder in turn; the stable section 1 of the cylinder can also be set Form two halves that are snapped together in the axial direction, place the damping net 5 and the filter screen 6 in the two halves of the stable section 1 of the cylinder, and then snap the two halves of the stable section 1 of the cylinder . The damping mesh 5 can make the flow velocity in the stable section more uniform, further destroy the vortex of the airflow passing through the honeycomb 41, and reduce the turbulence of the airflow in the stable section. Simultaneously, in the process of measuring the settling velocity of snow particles, the snow particles may melt, and the damping net 5 is arranged between the honeycomb 41 and the filter screen 6 to avoid corrosion of the honeycomb 41 after the snow particles melt, saving materials and cost .

As a specific implementation of the utility model embodiment, referring to Fig. 1, the length of the cylinder stabilization section 1 is 1.25-1.75 times the cross-sectional diameter of the cylinder stabilization section 1, and the airflow blown by the fan 3 is along the cylinder stabilization section 1. axial movement. Setting the length of the stable section 1 of the cylinder to 1.25-1.75 times the cross-sectional diameter of the stable section 1 of the cylinder mainly takes into account three factors, first of all, the stable section 1 of the cylinder can place the honeycomb 41, the damping net 5 and the filter screen 6, and a certain distance is set between the fan 3 and the honeycomb 41, and a certain distance is set between the damping net 5 and the filter screen 6, so that the air flow has a certain development length; followed by field tests, if the size of the device is too large, It is inconvenient to carry; finally, the fan 3 at the bottom occupies a certain space, and the length of the stable section 1 of the cylinder is appropriately lengthened. Generally, the space occupied by the fan 3 along the axial length of the stable section 1 of the cylinder is 25mm. Therefore, the length of the stable section 1 of the cylinder is finally set to be 1.25-1.75 times the cross-sectional diameter of the stable section 1 of the cylinder. The length of the cylinder test section 2 is not set to a fixed length, it is mainly set according to the proficiency of the operator, the longer the cylinder test section 2, the lower the requirements for the operator, so when measuring in the field, you can prepare different The length of the barrel test section 2, select different barrel test sections 2 according to the proficiency of the operator.

As a specific implementation of the utility model embodiment, please refer to Fig. 1, the length of the cylinder stabilization section 1 is 175mm, the diameter of the cylinder stabilization section 1 is 100mm, and the length of the rectification mechanism 4 is 60mm. Set the length of the stable section 1 of the cylinder to 175mm and the diameter to 100mm, which is convenient for carrying in the field. At the same time, a certain development length is reserved for the airflow blown by the fan 3, and the length of the rectification mechanism 4 is set to 60mm, which is more conducive to adjustment The turbulence of the airflow.

As a specific implementation of the utility model embodiment, please refer to Fig. 2, the snow particle settling velocity measurement device also includes a snow collection bucket 8, the two ends of the snow collection bucket 8 are open and the cross-sectional area in the horizontal direction is from the bottom to the bottom. The tops are incremented successively, and the bottom end is detachably connected to the outer surface of the stable section 1 of the cylinder body to collect snow particles after the measurement is completed. The snow collecting bucket 8 and the outer surface of the stable section 1 of the cylinder are preferably threaded, the inner side of the bottom of the snow collecting bucket 8 is provided with an internal thread, and the outer surface of the stable section 1 of the cylinder is correspondingly provided with an external thread; it can also be a frosted connection, The inner side of the bottom end of the snow collecting bucket 8 is set as a frosted surface, and the corresponding outer surface of the stable section 1 of the cylinder body is set as a frosted surface. After the snow particle settling velocity measurement is completed, increase the wind speed of the fan 3, so that the snow particles float out of the device and fall on the snow collecting bucket 8, so as to prevent the snow particles from falling on the filter screen 6 and melting to the damping net 5 and honeycomb 41 At the same time, the snow particles falling on the snow bucket 8 have a certain cooling effect on the stable section 1 of the cylinder.

As a specific implementation of the utility model embodiment, please refer to Fig. 1 and Fig. 2, the snow particle sedimentation velocity measuring device also includes a bracket 7, and the bracket 7 is used to support the stable section 1 of the cylinder body, and the bottom of the stable section 1 of the cylinder body The end is open, and the bracket 7 is used to support the stable section 1 of the cylinder body, which is convenient for cooling the fan 3 fixedly arranged on the stable section 1 of the cylinder body, and is beneficial to the stability of the overall device.

As a specific implementation of the utility model embodiment, please refer to Fig. 2, the snow particle sedimentation velocity measurement device also includes a heat pipe 9, the condensation section of the heat pipe 9 extends into the snow bucket 8, and the evaporation section of the heat pipe 9 passes through the cylinder The bottom end side surface of the stabilizing section 1 extends into the stabilizing section 1 of the cylinder body. The snow particles collected by the snow bucket 8 are used to cool down the fan 3 at the bottom of the stable section 1 of the cylinder body, so that the heat generated by the fan 3 can be quickly dissipated, and repeated experiments can be carried out at the same time, realizing the reuse of waste.

As a specific implementation of the embodiment of the present utility model, which is not shown in the figure, the anemometer is a hot wire anemometer. The top of the cylinder test section 2 is open, and the settling velocity of the snow particles can be measured by placing the measuring part of the anemometer at the nozzle of the cylinder test section 2. As the standard product of anemometer, hot wire anemometer is easy to carry and cost-effective.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model shall be included in this utility model. within the scope of protection of utility models.

Claims (8)

1. A snow particle sedimentation velocity measuring device, characterized in that, comprising: The stable section of the cylinder has open ends and a fan is fixed at the bottom end, and a rectifying mechanism for rectifying the airflow blown by the fan and a filter screen for placing snow particles are also provided in the stable section of the cylinder. The rectification mechanism is arranged at intervals above the top of the fan, and the filter screen is arranged at intervals above the top of the rectification mechanism; a cylinder test section, open at both ends, disposed on the upper end of said cylinder stabilization section and detachably connected to said cylinder stabilization section; and An anemometer, used to measure the wind speed at the end of the cylinder test section away from the cylinder stable section. 2. The snow particle sedimentation velocity measuring device according to claim 1, wherein the rectifying mechanism comprises a honeycomb. 3. The snow particle sedimentation velocity measurement device according to claim 2, wherein the rectification mechanism further comprises a damping net, and the damping net is arranged above the honeycomb. 4. The snow particle sedimentation velocity measuring device according to any one of claims 1-3, wherein the length of the stable section of the cylinder is 1.25-1.75 times the cross-sectional diameter of the stable section of the cylinder. 5. The snow particle sedimentation velocity measuring device according to any one of claims 1-3, wherein the length of the stable section of the cylinder is 175mm, the diameter of the stable section of the cylinder is 100mm, and the rectification The length of the mechanism is 60mm. 6. The snow particle settling velocity measuring device according to any one of claims 1-3, wherein the snow particle settling velocity measuring device further comprises: The snow bucket is open at both ends and the cross-sectional area in the horizontal direction increases successively from the bottom to the top. The bottom is detachably connected to the outer surface of the stable section of the cylinder, and is used to collect snow particles after the measurement is completed. 7. The snow particle sedimentation velocity measurement device according to any one of claims 1-3, wherein the snow particle sedimentation velocity measurement device further comprises: The bracket is used to support the stable section of the cylinder. 8. The snow particle sedimentation velocity measurement device according to any one of claims 1-3, wherein the anemometer is a hot wire anemometer.