Fluidic Oscillators, Feedback Channel Effect under Compressible Flow Conditions

Sensors

Bhanu Prakash¹  Fernando Mellibovsky²  Masoud Baghaei³  Josep M. Bergadà³ 

[1] Applus IDIADA Group, Santa Oliva, L’Albornar, 43710 Tarragona, Spain;Department of Physics, Aerospace Engineering Division, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain;Fluid Mechanics Department, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain;

关键词: fluidic oscillators;    feedback channel performance;    3D-Computational Fluid Dynamics (CFD);    Direct Numerical Simulation (DNS);    compressible flow;    boundary layer;   

DOI  :  10.3390/s21175768

来源: DOAJ

【 摘 要 】

Fluidic oscillators are often used to modify the forces fluid generates on any given bluff body; they can also be used as flow, pressure or acoustic sensors, with each application requiring a particular oscillator configuration. Regarding the fluidic oscillators’ main performance, a problem which is not yet clarified is the understanding of the feedback channel effect on the oscillator outlet mass flow frequency and amplitude, especially under compressible flow conditions. In order to bring light to this point, a set of three-dimensional Direct Numerical Simulations under compressible flow conditions are introduced in the present paper; four different feedback channel lengths and two inlet Reynolds numbers $Re$ = 12,410 and $Re$ = 18,617 are considered. From the results obtained, it is observed that as the inlet velocity increases, the fluidic oscillator outlet mass flow frequency and amplitude increase. An increase of the feedback channel length decreases the outlet mass flow oscillating frequency. At large feedback channel lengths, the former main oscillation tends to disappear, the jet inside the mixing chamber simply fluctuates at high frequencies. Once the Feedback Channel (FC) length exceeds a certain threshold, the oscillation stops. Under all conditions studied, pressure waves are observed to be traveling along the feedback channels, their origin and interaction with the jet entering the mixing chamber are thoroughly evaluated. The paper proves that jet oscillations are pressure-driven.

【 授权许可】

Unknown