Optimization of Local Heat Transfer in Impact Jet Using Active Flow Control and Feedback

Abstract

The development of methods for controlling flow and heat transfer in submerged turbulent jets (impact jets) impinging on an obstacle is an important problem, since this configuration is used in various technical applications. Active flow control technology and optimization of the signal that controls the external flow disturbance in impact jets can be applied to use the inherent properties of the flow to further improve heat transfer at the wall. This work used IR thermography and PIV (particle image velocimetry) measurements for optical diagnostics of wall temperature fields and velocity fields under conditions of flow rate disturbance control, including feedback from a local velocity sensor. It was found that low-amplitude sinusoidal disturbances increase the integral temperature on the wall due to the intensification of flow separation on the wall compared to an undisturbed jet. It has also been established that high-amplitude disturbances in the pulsating jet mode make it possible to reduce the integral temperature by increasing the average flow velocity near the wall and compensate for unwanted flow separation. The genetic programming algorithm made it possible to find a self-oscillating mode in jet disturbance with feedback, which improves local heat transfer on the wall no worse than in the case of forced periodic disturbance.