CN115406616A

CN115406616A - Wind resistance detection and analysis method

Info

Publication number: CN115406616A
Application number: CN202211159779.2A
Authority: CN
Inventors: 郭健; 毋少峰; 倪静; 王志强
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2022-09-22
Filing date: 2022-09-22
Publication date: 2022-11-29

Abstract

The invention discloses a wind resistance detection and analysis method; the method comprises the following steps: 1. arranging a mounting hole group on the windward side of the structure to be tested; the density of the mounting holes of the plane part of the windward side is less than that of the mounting holes of the curved part of the windward side. 2. A pressure measuring unit is installed in each of the installation holes. And covering a color development layer on the windward side of the structure to be detected. The color development layer adopts a flexible display screen. When the pressure measuring unit detects different pressures, the corresponding positions on the flexible display screen display different colors. 3. Placing the structure to be measured in a wind tunnel; the wind tunnel applies different wind power to the measured structure, and each pressure measuring unit respectively detects the pressure change of the pressure measuring unit; and different positions of the color development layer display different colors according to the pressure measured by the corresponding pressure measurement unit. The invention can intuitively show the wind resistance conditions of windward sides with different shapes through the color change of the color development layer in the wind resistance test, thereby helping designers to improve the aerodynamics of the tested structure.

Description

Wind resistance detection and analysis method

Technical Field

The invention relates to the technical field of wind resistance detection, in particular to a wind resistance detection analysis method.

Background

When fluid surface pressure or pressure bearing surface pressure is measured, the existing measuring mode can only carry out pressure measurement on individual points of the surface or overall pressure evaluation on a local surface, but cannot measure the specific distribution condition of the surface pressure. But measuring surface pressure distribution, especially micro-pressure distribution, is particularly important, where a pressure sensor for a certain point cannot accomplish this goal. In the prior art, wind resistance detection of a windward structure is mostly carried out through a wind tunnel; however, the existing wind resistance detection mode is difficult to intuitively see the wind resistance conditions of different positions of the windward side on a detected structure.

Disclosure of Invention

The invention aims to provide a wind resistance detection and analysis method.

A wind resistance detection and analysis method comprises the following steps:

step one, arranging a mounting hole group on the windward side of a structure to be tested; the density of the mounting holes of the plane part of the windward side is less than that of the mounting holes of the curved part of the windward side.

And step two, installing a pressure measuring unit in each installation hole. And a color development layer is covered on the windward side of the structure to be detected. The color development layer adopts a flexible display screen. When the pressure measuring unit detects different pressures, the corresponding positions on the flexible display screen display different colors.

Step three, placing the structure to be measured into a wind tunnel; the wind tunnel applies different wind power to the measured structure, and each pressure measuring unit respectively detects the pressure change of the pressure measuring unit and uploads the pressure change to the controller. The controller controls different positions of the color development layer to display different colors according to the pressure measured by the corresponding pressure measurement unit. And the working personnel judge the wind resistance conditions of the whole and the local part of the tested structure according to the colors of different positions of the tested structure.

Preferably, the center distance between two adjacent mounting holes on the plane part of the windward side is 3cm; the center distance between two adjacent mounting holes on the curved surface part of the windward side is 1cm.

Preferably, the structure to be measured is a shell of a vehicle.

Preferably, the pressure measurement unit comprises a graphene film, a Fabry-Perot cavity, a multimode fiber, a light source and a spectrum acquisition system. The cross-sectional shape of the multimode optical fiber is the same as the cross-sectional shape of the mounting hole. A Fabry-Perot cavity is formed in one end of the multimode optical fiber, and a graphene film is arranged on the multimode optical fiber. The outer side surface of the graphene film is flush with the detection surface of the detected structure. The other end of the multimode fiber is provided with a light source and is connected with an optical signal input interface of the spectrum acquisition system. Light emitted by the light source is transmitted in the multimode optical fiber and is reflected at the Fabry-Perot cavity. The spectrum acquisition system detects the interference condition of Fabry-Perot cavity reflected light and judges the pressure applied to the graphene film according to the interference change condition.

Preferably, the detection part of the pressure measurement unit is flush with the windward side of the structure to be measured.

Preferably, the spectrum acquisition system adopts a fiber grating demodulator.

Preferably, the Fabry-Perot cavity is an air cavity formed on the end face of the optical fiber through chemical corrosion.

The invention has the following beneficial effects:

1. the invention can intuitively show the windage conditions of windward sides with different shapes through the color change of the color development layer in the windage test, thereby helping designers to improve the aerodynamics of the tested structure.

2. The invention realizes multi-point micro-pressure measurement on a measured structure in any shape through a distributed pressure measurement array, thereby achieving comprehensive detection of integral and local wind resistance.

Drawings

The invention is further described below with reference to the accompanying drawings.

FIG. 1 is a schematic structural view of example 1 of the present invention;

FIG. 2 is a schematic structural view of a pressure measuring unit in embodiment 1 of the present invention;

FIG. 3 is a schematic view of the working principle of the pressure measuring unit in embodiment 1 of the present invention;

fig. 4 is a schematic signal transmission diagram of the pressure measurement unit in embodiment 1 of the present invention.

Fig. 5 is a schematic front view of a structure to be measured in a wind tunnel in embodiment 2 of the present invention.

Fig. 6 is a schematic side view of a structure to be measured in a wind tunnel according to embodiment 2 of the present invention.

Reference numerals are as follows: in fig. 1 and 2, 1 is a graphene thin film; 2 is a Fabry-Perot cavity; 3 is a multimode optical fiber; 4 is a pressure measuring unit; and 5, a structure to be measured. In FIG. 3, L0 is the lumen length; e0 is the incident light amplitude; e1 is the amplitude of the reflected light on the Fabry-Perot cavity; e2 is the amplitude of the reflected light in the Fabry-Perot cavity; e2i is the amplitude of incident light in the graphene; e2r is the amplitude of the reflected light at the graphene. In fig. 5 and 6, 6 is the structure to be measured, 7 is a wind tunnel.

Detailed Description

The invention will now be described more closely with reference to examples.

Example 1

As shown in fig. 1, a distributed measurement system for micro-pressure measurement includes a structure to be measured 5, a pressure measurement unit 4, a color development layer, and a controller. The detection surface of the detected structure 5 may be a plane or a curved surface. The detection surface of the detected structure 5 is provided with an array of mounting holes. The mounting hole array comprises a plurality of mounting holes which are arranged in a matrix shape. A pressure measuring unit 4 is mounted in each mounting hole. The center distance between two adjacent mounting holes is 1cm. The color-developing layer is arranged on the detection surface of the detected structure 5. The detection part of the pressure measurement unit 4 is flush with the detection surface of the structure 5 to be detected, so that the accuracy of the data measured by the sensor is ensured. The structure 5 to be measured is the windward side of a car or a motor car.

The pressure measuring unit 4 comprises a graphene film 1, a Fabry-Perot cavity 2, a multimode fiber 3, a light source (not shown in the figure) and a spectrum acquisition system (not shown in the figure). The cross-sectional shape of the multimode optical fiber 3 is the same as the cross-sectional shape of the mounting hole. One end of the multimode optical fiber 3 is provided with a Fabry-Perot cavity 2; the opening of the Fabry-Perot cavity 2 is pasted and covered with a graphene film 1. The outer side surface of the graphene film 1 is flush with the detection surface of the detected structure 5. The other end of the multimode fiber 3 is provided with a light source and is connected with an optical signal input interface of the spectrum acquisition system. The Fabry-Perot cavity 2 is an air cavity formed on the end face of the optical fiber through chemical corrosion. In this embodiment, the light source is integrated in the spectrum acquisition system.

During operation, light emitted by the light source is transmitted in the multimode optical fiber 3 and reflected at the Fabry-Perot cavity 2. The spectrum acquisition system detects the interference condition of the reflected light of the Fabry-Perot cavity 2. When the graphene film 1 is under pressure, the Fabry-Perot cavity 2 deforms, so that the reflection characteristic of the Fabry-Perot cavity 2 is changed, and the interference condition measured by the spectrum acquisition system changes. The spectrum acquisition system adopts a fiber grating demodulator. Specifically, the pressure measurement unit 4 measures the pressure by detecting light, and the specific principle is that after the incident light enters the fabry-perot cavity, part of the incident light is reflected back by the graphene, and the other part of the incident light is reflected back by the concave surface of the optical fiber (i.e., the interface of the fabry-perot cavity), and the two parts of light have the same frequency, so that an interference phenomenon occurs. When pressure on the graphene film changes, the film is deformed, and therefore reflected light interference light changes. When the graphene film is deformed due to pressure change, the interference spectrum of the reflected light is changed, the change of the cavity length can be known by detecting the change of the reflected light, and the change condition of the pressure can be further known by calculation. The dimensionless relational expression of the pressure and the cavity length change is known to be L =50-30 xP through theoretical derivation; l is the cavity length, the unit is mum, P is the pressure, the unit is MPa, the measurement range of the pressure is from 0 to 0.1MPa, and the measurement precision is not less than 50nm/kPa.

The fiber grating demodulator can conveniently transmit and remotely control the acquired data, and set the frequency of a 5Hz light source and the sampling time interval of 10 times per minute. The quantity of information collected by the fiber grating demodulator is large, so that the collected data needs to be detected and analyzed, some disturbance is filtered, burrs and distortion are avoided in the collected data, and the data is processed by using a smooth function, so that a finally obtained data curve becomes smooth.

A software system in the controller needs to realize data acquisition, calculate the pressure and store the data so as to facilitate subsequent processing. The color rendering layer adopts a flexible display screen; the color-developing layer is capable of displaying different colors at different positions under the control of the controller. And establishing a mapping relation between different pressure values and different colors. According to the pressure change of different positions on the measured structure, the colors of different positions of the color development layer are adjusted, so that the surface pressure of the measured structure 5 can be visually observed.

Example 2

As shown in fig. 5 and 6, a wind resistance detection analysis method includes the following steps:

step one, arranging a mounting hole array on the windward side of a tested structure 6; the center distance between two adjacent mounting holes on the plane part of the windward side is 3cm; the center distance between two adjacent mounting holes on the curved surface part of the windward side is 1cm. The accuracy of the wind resistance measurement can be adjusted by varying the density of the mounting holes. In this embodiment, the structure 6 to be measured is an automobile or a motor car.

And step two, installing the pressure measuring unit 4 in each installation hole. The structure of the pressure measuring unit 4 is the same as that described in embodiment 1. And a color development layer is covered on the windward side of the structure to be detected. The color development layer adopts a flexible display screen. When the pressure measuring unit 4 detects different pressures, the corresponding positions on the flexible display screen display different colors. Therefore, the pressure change condition on the windward side is visually displayed on the measured structure in a color mode.

Step three, placing the structure to be measured into the wind tunnel 7; the wind tunnel 7 applies different wind forces to the structure to be measured, and each pressure measuring unit 4 respectively detects the pressure change of the pressure measuring unit and uploads the pressure change to the controller. The controller controls different positions of the color-developing layer to display different colors according to the pressure measured by the corresponding pressure measurement unit 4. And a software system in the controller realizes the collection of spectral data, calculates the pressure and outputs a color distribution signal. According to the port of the customized distributed film type pressure sensor, the controller controls the light source frequency, the sampling frequency and the sampling time interval of the whole system, the data of the sensor are processed, and the pressure distribution condition of the whole surface can be calculated through the controller.

The staff judges the wind resistance size of this structure under different wind-force according to the colour of the different positions of survey structure, and then carries out aerodynamic improvement and perfect to the shape of survey structure.

Claims

1. A wind resistance detection and analysis method is characterized by comprising the following steps: the method comprises the following steps:

step one, arranging a mounting hole group on the windward side of a structure to be tested; the density of the mounting holes of the plane part of the windward side is less than that of the mounting holes of the curved part of the windward side;

step two, installing a pressure measuring unit (4) in each installation hole; covering a color development layer on the windward side of the structure to be detected; the color rendering layer adopts a flexible display screen; when the pressure measuring unit (4) detects different pressures, the corresponding positions on the flexible display screen display different colors;

thirdly, placing the structure to be measured into a wind tunnel; the wind tunnel applies different wind power to the measured structure, and each pressure measuring unit (4) respectively detects the pressure change of the pressure measuring unit and uploads the pressure change to the controller; the controller controls different positions of the color development layer to display different colors according to the pressure measured by the corresponding pressure measurement unit (4); and the working personnel judge the wind resistance conditions of the whole and the local part of the tested structure according to the colors of different positions of the tested structure.

2. The wind resistance detection and analysis method according to claim 1, wherein: the center distance between two adjacent mounting holes on the plane part of the windward side is 3cm; the center distance between two adjacent mounting holes on the curved surface part of the windward side is 1cm.

3. The wind resistance detection and analysis method according to claim 1, wherein: the structure to be measured is a shell of a vehicle.

4. The wind resistance detection and analysis method according to claim 1, wherein: the pressure measurement unit (4) comprises a graphene film (1), a Fabry-Perot cavity (2), a multimode optical fiber (3), a light source and a spectrum acquisition system; the cross section shape of the multimode fiber (3) is the same as that of the mounting hole; one end of the multimode fiber (3) is provided with a Fabry-Perot cavity (2) and a graphene film (1); the outer side surface of the graphene film (1) is flush with the detection surface of the detected structure (5); the other end of the multimode optical fiber (3) is provided with a light source and is connected with an optical signal input interface of the spectrum acquisition system; light emitted by the light source is transmitted in the multimode optical fiber (3) and is reflected at the Fabry-Perot cavity (2); the spectrum acquisition system detects the interference condition of the reflected light of the Fabry-Perot cavity (2), and judges the pressure applied to the graphene film (1) according to the interference change condition.

5. The wind resistance detection and analysis method according to claim 5, wherein: the detection part of the pressure measurement unit (4) is flush with the windward side of the structure to be detected.

6. The wind resistance detection and analysis method according to claim 5, wherein: the spectrum acquisition system adopts a fiber grating demodulator.

7. The wind resistance detection and analysis method according to claim 5, wherein: the Fabry-Perot cavity (2) is an air cavity formed on the end face of the optical fiber through chemical corrosion.