Flow Control In Industrial Injection Applications By Changing The Exit Splitter Positions Inside A Fluidic Oscillator Ahmed Mohamed Abdulnaim Mohamed by Ahmed Mohamed Abdulnaim Mohamed instant download after payment.

The fluidic oscillator shows very promising outcomes as an actuator in active flow control applications. It features several important characteristics including no moving parts, self-excitation, rigidity, and reliability. The fluidic oscillator can be used in many diverse applications including (i) active combustion control in jet engines, (ii) development of the next-generation heat exchangers with extremely high heat flux removal capacity, and (iii) flow separation control on diverse aerodynamic profiles.

This study deals with a double feedback fluidic oscillator, where the design was adopted from a previous study, which developed the actuator to meet working as a pilot oscillator inside swirl stabilized burners for gas turbines applications. Many experimental and computational investigations were obtained on fluidic oscillators to understand the internal flow dynamics and oscillation characteristics and determine the parameters affecting the actuator performance and the oscillation process. However, there is still lacking in appraising the impact of the exit configuration and exit splitter position on the flow fields and oscillation characteristics.

The present work investigates computationally the influence of the exit configuration as well as splitter position on the flow fields and oscillation characteristics inside and outside the fluidic oscillator. The methodology of the study is divided into two groups:

(A) Study the effect of exit configuration:

(i) The inclusion of a splitter inside the exit channel (configuration FX100),

(ii) The removal of the slitter with retaining the exit channel (configuration FX0), and

(iii) The whole elimination of both the exit channel and splitter (configuration FX0').

(B) Study the effect of splitter position by gradually moving it downstream the oscillator (configurations FX75, FX50, and FX25).

To provide experimental data for the process of validation, experimental results were adopted from a previous study using particle image velocimetry (PIV) laser system with water as a working fluid and time-resolved pressure measurements using a hydrophone.

Two-dimensional computational models based on Unsteady Reynolds-averaged Navier-Stokes (URANS) equations and shear stress transport (SST) were utilized to perform the computational work considering the flow to be turbulent, incompressible, and isothermal.

The simulation results indicate that the exit configuration has no significant effects on the frequencies, while the jet deflection angle of the outflowing jet increases and the jet tends to be continuous when the splitter is eliminated (configurations FX0 and FX0'). The existence of the splitter (configuration FX100) increases the outflow velocity fluctuation amplitudes which would be useful in diverse industrial applications.

The splitter position does not affect the actuator’s frequency, but it changes the amplitude in an irregular manner. The size of the inner recirculation zone is inversely proportional to the splitter position. The emanating jets are deflecting due to shortening the splitter, which shortens the exit limbs' paths.