Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Collection
For ¥0.57 per day, unlimited downloads CREATE MEMBERSHIP Download

toTop

If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

home > search >

Calibration of a system for measuring low air flow velocity in a wind tunnel

Author:
Andrzej Krach   Janusz Kruczkowski  


Journal:
Metrologia


Issue Date:
2016


Abstract(summary):

This article presents the calibration of a system for measuring air flow velocity in a wind tunnel with a multiple-hole orifice. The comparative method was applied for the calibration. The method consists in equalising the air flow velocity in a test section of the tunnel with that of the hot-wire anemometer probe which should then read zero value. The hot-wire anemometer probe moves reciprocally in the tunnel test section with a constant velocity, aligned and opposite to the air velocity. Air velocity in the tunnel test section is adjusted so that the minimum values of a periodic hot-wire anemometer signal displayed on an oscilloscope screen reach the lowest position (the minimum method). A sinusoidal component can be superimposed to the probe constant velocity. Then, the air flow velocity in the tunnel test section is adjusted so that, when the probe moves in the direction of air flow, only the second harmonic of the periodically variable velocity superimposed on the constant velocity (second harmonic method) remains at the output of the low-pass filter to which the hot-wire anemometer signal, displayed on the oscilloscope screen, is supplied. The velocity of the uniform motion of the hot-wire anemometer probe is measured with a magnetic linear encoder.The calibration of the system for the measurement of low air velocities in the wind tunnel was performed in the following steps:1. Calibration of the linear encoder for the measurement of the uniform motion velocity of the hot-wire anemometer probe in the test section of the tunnel.2. Calibration of the system for measurement of low air velocities with a multiple-hole orifice for the velocities of 0.1 and 0.25 m s−1:- (a) measurement of the probe movement velocity setting;- (b) measurement of air velocity in the tunnel test section with comparison according to the second harmonic method;- (c) measurement of air velocity in the tunnel with comparison according to the minimum method.The calibration uncertainties were calculated after the measurements.


Page:
1012---1023


VIEW PDF

The preview is over

If you wish to continue, please create your membership or download this.

Create Membership

Similar Literature

Submit Feedback

This function is a member function, members do not limit the number of downloads