Experimental Study of the Influence of a Blowing Grid on Turbulent Jets Applied to Air Conditioning Systems

To overcome the challenges associated with homogenising the aerodynamic parameters of turbulent air jets, special attention must be given to the design of air jet distribution systems. This study aimed to evaluate the performance of two air jet distribution systems, one (AG) equipped with a blowing grid and the other (SG) without, at different frequencies. The frequency parameter was selected due to its proportional relationship with velocity, which allowed for precise control over the inlet flow velocity. Experiments were conducted in a controlled environment using a wind tunnel connected to a test chamber at the Control, Testing, Measurement, and Mechanical Simulation Laboratory of the University of Chlef. The results showed that in the axial direction, the blowing grid caused a reversal in velocity trends, indicating recirculation zones, especially at a frequency N1=40Hz. Conversely, the gridless configuration exhibited a more uniform velocity distribution. At a frequency N2=50Hz, the increase in instabilities induced turbulence and flow disturbances, leading to a degradation of the velocity distribution. In the radial direction, the blowing grid improved the diffusion of kinetic energy, resulting in a more homogeneous jet spread and a uniform velocity distribution, especially further from the nozzle. The turbulence intensity in the AG configuration increased by 4% near the chamber wall, a finding that was consistent with shear-induced effects. The system equipped with the blowing grid proved more effective in promoting a consistent radial distribution of airflow. This enhanced flow uniformity is essential for applications requiring precise control of aerodynamic parameters. Ultimately, the blowing grid configuration emerged as the optimal solution for achieving a more homogeneous and stable airflow profile.