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Manipulating Pattern Factors Using Synthetic Jet Actuators

Manipulating Pattern Factors Using Synthetic Jet Actuators. Y. Chen Advisor: J. Jagoda School of Aerospace Engineering Georgia Institute of Technology. Outline. Objective Quick Review Quantify the Degree of Mixing Results of Using Different Actuator Orifice

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Manipulating Pattern Factors Using Synthetic Jet Actuators

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  1. Manipulating Pattern Factors Using Synthetic Jet Actuators Y. Chen Advisor: J. Jagoda School of Aerospace Engineering Georgia Institute of Technology

  2. Outline • Objective • Quick Review • Quantify the Degree of Mixing • Results of Using Different Actuator Orifice • Literature Review of Jets with or without Cross-Flow • Ongoing Work

  3. Objective • Determine the mechanisms responsible for the manipulation of temperature distributions in combustion products entering the turbine (pattern factor) using synthetic jets • Optimize the effect of synthetic jets on pattern factor control

  4. Synthetic Jet Arrangement Slot 1.6 mm x11.2 mm Present Ori fice Plate Configura tion 2.38mm D Orifice Plate 4 Holes, 4mm Apart 20mm D x 5 m m Y X Flow Z X Bottom Chamber W all

  5. X/D=90 Cold air flow velocity = 2.75m/s

  6. Temperature Distribution No actuation Uj = 6.5m/s Uj = 23.3m/s

  7. Temperature Profiles at Different Orifices 4-holes (cross) slot (cross) Uj=0m/s Uj=3.2m/s Uj=6.5m/s Uj=9.8m/s

  8. Evaluate the Degree of Mixing Quantitatively • Basic idea: the entropy increases as the temperature profile becomes more uniform. • Assumptions: constant gas properties (Cp, R) • Ideal fully mixed state: a state identified by a uniform temperature calculated from energy conservation • Entropy increase • Normalized entropy

  9. Evaluate the Degree of Mixing Quantitatively Without actuation With actuation

  10. Compare the Effects of Different Orifices

  11. Using Different Actuators

  12. Literature Review of Jets with or without cross flow Four kinds of vortex structures when steady jets issued into a cross-flow* * T. Fric, A. Roshko

  13. Literature Review of Jets with or without cross flow Multiple steady jets in cross flow The variation of parameters such as orifice spacing and the orientation with respect to the cross-flow (e.g. tandem or side-by-side) will affect the interaction between jet and jet and between the jets and the cross-flow

  14. Literature Review of Jets with or without cross flow Noncircular steady jets vortex structure* • The deformation of vortices in a rectangular jet is so severe that the major axis sides come close to each other, collide, and cross-link, and the original single vortex ring bifurcates to two small vortices via the so-called “cut-and-connect process” • Noncircular jets are very effective in the enhancement of mixing * K. Toyota, F. Hussain

  15. Literature Review of Jets with or without cross flow Impingement Vortex It is not a vortex in the sense of increasing local velocities as the core is approached. It is a turbulent separation bubble inside which the jet and cross-flow mix* * W. Blake, et al

  16. Literature Review of Jets with or without cross flow Unsteady Jets have some significant distinct properties Vortex Ring A vortex ring is created when a fluid parcel is impulsively discharged from a circular opening H. Hura, et al

  17. Literature Review of Jets with or without cross flow Pulsed Jets “Puffs” generated as the jet is modulated introduce additional supplementary mixing. Optimal mixing conditions are based on velocity ratio, duty ratio and pulse injection frequency. The vortex structure characteristic of steady injection is obtained at the stable stage of the evolution of the pulsed jet.

  18. Literature Review of Jets with or without cross flowSynthetic Jet Actuators* • Zero net mass flow actuator produces two different types of flowfield depending on frequency and amplitude of the actuation. • Low frequency and high amplitude sucks from near-field and blows to far-field; High frequency and low amplitude sucks from far-field and blows to near-field. * J. Gilarranz, et al

  19. Ongoing Work • Determine which (if any) mixing mechanisms described in literature relevant here • Repeatability • Add more configurations • Flow visualization • Flow-field measurement (more details)

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