Design and Performance Evaluation of an Open Loop Wind Tunnel at NIS

Abstract

This study presents the design and evaluation of wind tunnel performance at the National Institute of Standards in Egypt. Flow contraction in the convergent nozzle of a subsonic wind tunnel is one of the most effective means of reducing the level of turbulence intensity in the testing section. Accordingly, this study is based on designing a contraction ratio of 7, and comparing this ratio with previous studies in terms of turbulence intensity. The construction steps for the major components of the wind tunnel and calibration procedure are described. The calibration results show that the present wind tunnel provides a good repeatability of ± 0.003 m/s. In addition, reproducibility conditions provide a high confidence level in the results obtained from long-term investigations, with satisfactory performance. The results of the experimental study on the influence of flow contraction on the mean turbulence intensity in the convergence nozzle of an open-loop subsonic wind tunnel were less than 0.5%. In addition, the accuracy and stability of the wind tunnel design were verified using statistical evaluation of the normalized error value (En-value). The results indicate that the maximum normalized error of the measurement at the end of the test section was 0.8.