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Flow structure transport measurements in complex nozzles with High-Speed PIV

Ganeshan, Keerthan
http://orcid.org/0009-0001-6736-3717
http://rave.ohiolink.edu/etdc/view?acc_num=ucin172123270314926

Abstract Details

2024, MS, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
This study underlines the impact of the flow structures on the internal flow field through shape-transitioning ducts with global favorable pressure gradients and local adverse pressure gradients, local to the shape-transitioning geometries. Results are evaluated for convergence apropos of acquisition frequency. This thesis presents preliminary results of flow structure measurement by introducing the structures with a cylindrical bluff body in the cross flow. Structure transport through the two duct configurations studied includes the free jet of a convergent nozzle and through a shape-transitioning nozzle. Particle Image Velocimetry (PIV) was employed in data acquisition considering its substantial spatiotemporal resolution necessary. Findings show that the free jet results are characterized by high-velocity jets, detached velocity deficit region at the tailing edge of the cylinder, and strong velocity gradients due to the shear layers formed between the wake, the jets, and the ambient. On the contrary, flow through the shape transitioning or favorable pressure gradient (FPG) nozzle reflects a well-behaved flow with a low-velocity region attached to the cylinder in most cases. The outcome difference primarily stems from the velocity experienced at the cylinder in each case. An examination of convergence, considering the acquiring frequency of the flow field data, unveiled a weighty impact of acquisition frequency on the results of turbulent flow fields. The ensemble average of the results based on the mathematical computation using analytical methods in the time domain revealed an overall comparable trend in results with notable distinctions in the near wake region. Convergence dependence of results on flow essence emerged with a comparison of the running averages at a point within and outside the wake. In conclusion, it was established that a smaller subset of image pairs drawn from a universal set is ample for effectively capturing the physics of the flow field in PIV. The presented results demonstrate the preliminary measurements of the transport of flow structures within ducts with a global favorable pressure gradient, conjoined with localized adverse pressure gradients resulting from shape transitions. These studies shed light on their influence on the flow field dynamics and overall component performance. Additionally, the study delves into the influence of acquisition frequency on the result convergence. Finally, a Flow Conditioning System (FCS) was designed and fabricated to enhance the flow quality through the flow rig, which was initially characterized by significant velocity fluctuations and unsteadiness. Furthermore, a Secondary Flow System (SFS) was developed to introduce these flow structures through ducts as a coaxial flow system with a nozzle head versatile to accommodate flow structure generators.
Daniel Cuppoletti, Ph.D. (Committee Chair)
Shaaban Abdallah, Ph.D. (Committee Member)
Paul Orkwis, Ph.D. (Committee Member)
177 p.
Aerospace Materials
Favorable Pressure Gradient; Shape transition nozzle; Nozzle flow structure measurements; High-Speed Particle Image Velocimetry; Flow system design; PIV Convergence

Recommended Citations

Citations

  • Ganeshan, K. (2024). Flow structure transport measurements in complex nozzles with High-Speed PIV [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin172123270314926

    APA Style (7th edition)

  • Ganeshan, Keerthan. Flow structure transport measurements in complex nozzles with High-Speed PIV. 2024. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin172123270314926.

    MLA Style (8th edition)

  • Ganeshan, Keerthan. "Flow structure transport measurements in complex nozzles with High-Speed PIV." Master's thesis, University of Cincinnati, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=ucin172123270314926

    Chicago Manual of Style (17th edition)

ucin172123270314926
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This open access ETD is published by University of Cincinnati and OhioLINK.