GB/T 2423.41-2013Environmental testing - Part 2: Test methods - Wind pressure (English PDF)

2.1 Wind tunnel

A piping system, which is designed according to special requirements, uses a fan and other power devices to artificially generate and control airflow, to simulate the airflow around the test piece AND measure the effect of the airflow on the test piece. The part, where the test piece is installed, is called the test section.

Wind tunnels, which have wind speeds lower than 135 m/s, are called low-speed wind tunnels.

2.2 Wind tunnel test

Install the test piece in the test section of the wind tunnel; measure the aerodynamic force acting on the test piece, when the air flows through the […]

2.7 Aerodynamic coefficient

The aerodynamic force (torque) is divided by the characteristic area of the test piece (the characteristic area times the characteristic length) AND the dimensionless coefficient of the air flow pressure.

Aerodynamic coefficient Cr = F/(Q · S); Aerodynamic torque coefficient Cm = M/(Q · S · L). Among them, F and M are the force and moment, respectively;

Cr and Cm are their coefficients, respectively; S is the characteristic area, which is, in this Part, the maximum projected area of the solid part of the test piece; L is the characteristic length, which is, in this Part, the maximum extension length of the solid part of the test piece; Q is dynamic pressure, Q = 0.5 · rho · v2 (where rho is air density, v is wind speed).

2.8 Wind pressure

The pressure, which is generated on the surface of the test piece, when the air flows through it. The wind pressure coefficient is Cp = (p1 - pinfinity)/Q, where p1 is the pressure value at a certain point of the test piece; pinfinity is the static pressure value, which is not disturbed by the test piece, far in front of the incoming flow.

2.9 Wind speed

The relative speed of the test piece and the airflow. For the test piece, which is installed on the moving equipment (such as ship radar), it refers to the vector sum of the wind speed in the atmosphere AND the moving speed of the equipment.

2.10 Reynolds number

The dimensionless parameter, which characterizes the relative magnitude of the air inertial force and viscous force, which is denoted as Re. Re = (rho · v · L)/µ, where rho is the air density, µ is the dynamic viscosity coefficient of the air, v is the wind speed, L is the characteristic length.

2.11 Body axes system

The orthogonal coordinate axis systems ox1, oy1, oz1 (see Figure 1), which are fixed on the test piece. It conforms to the right-hand rule.

2.12 Wind axes system

The reference orthogonal coordinate axis system ox, oy, oz, based on the airflow direction (see Figure 1). It conforms to the right-hand rule.

4.1 Test wind speed

The test wind speed is 15 m/s, 30 m/s, 35 m/s, 45 m/s, 52 m/s, OR according

5.2.2 Force measurement in rotating state

5.2.2.1 The test piece is installed in the test section of the wind tunnel, according to the state of use. Increase the wind speed to 35 m/s OR according to the requirements of the relevant specifications, adjust and change the angle according to 4.2, to start the test piece; measure the force and torque. At the same time, carry out the test according to the requirements of the relevant specifications; AND whether to power on to test the performance index.

5.2.2.2 The test piece is installed in the test section of the wind tunnel, according to the state of use. Increase the wind speed is to 52 m/s OR according to the requirements of the relevant specifications, adjust and change the angle according to 4.2, to start the test piece; measure the force and torque.

At the same time, carry out the test according to the requirements of the relevant specifications; AND whether to power on to test the performance index.

5.2.3 Pressure measurement in stationary state

The test piece is installed in the test section of the wind tunnel, according to the state of use, during the pressure measurement in stationary state. Carry out pressure measurement, according to the test conditions required by 4.1 and 4.2 OR relevant specifications. At the same time, the test the performance index, according to the test conditions, which are required by the relevant specifications.

For test pieces that are installed close to the ground, or have larger objects around which affect air flow, a typical case shall be selected for simulation test, to provide magnitude of the possible impact.

5.2.4 Deformation measurement of flexible components

For test pieces with greater flexibility, it shall also paste a pre-calibrated strain gauge, on the relevant positions of the test pieces, to measure the deformation on the relevant components of the test pieces.

5.3 Final inspection

Under standard atmospheric conditions, carry out testing of the electrical performance, mechanical performance of the test piece, as well as visual inspection, OR according to relevant specifications.