Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Mechanical Engineering
Numerical Simulation Of Vortex Generating Jets In Zero And Adverse Pressure Gradients, Curtis Lynn Memory
Numerical Simulation Of Vortex Generating Jets In Zero And Adverse Pressure Gradients, Curtis Lynn Memory
Theses and Dissertations
Numerical simulations of particle image velocimetry (PIV) experiments conducted with vortex generating jets (VGJs) on a flat plate, at a Reynolds number based on plate length of 50,000, were performed for three flow conditions using a time-accurate hybrid Navier-Stokes solver. Time-averaged steady blowing of angled jets, subjected to a zero pressure gradient, yielded excellent agreement with the PIV data in terms of vortex formation and strength. Observed flow features include primary and secondary vortices, where the primary vortex eventually dominates the downstream region. A shell wall structure, created by smaller vortical structures surrounding the developing vortices, was also observed. A …
Piv Measurements Of Exit Flow Field Of Centrifugal Fans With Conditional Sampling, Shun-Chang Yen, Jung-Hsuan Liu
Piv Measurements Of Exit Flow Field Of Centrifugal Fans With Conditional Sampling, Shun-Chang Yen, Jung-Hsuan Liu
Journal of Marine Science and Technology
In this research, we have experimented with two centrifugal fans with the same geometrical configuration. These two fans are designed to rotate at different speeds driven with the same voltage. The Particle Image Velocimetry (PIV) method is applied to measure the instantaneous flow fields at the near-exit region. The AMCA 210 wind tunnel is used to find the efficiency and the performance coefficients. The velocity vectors, streamlines, vorticity contours, velocity distributions, flow rate, and performances are also presented and discussed. We find that higher rotation speed yields better efficiency.
The Effects Of Vortex Generator Jet Frequency, Duty Cycle, And Phase On Separation Bubble Dynamics, Matthew J. Bloxham
The Effects Of Vortex Generator Jet Frequency, Duty Cycle, And Phase On Separation Bubble Dynamics, Matthew J. Bloxham
Theses and Dissertations
Vortex generator jets (VGJs) have proven to be effective in minimizing the separation losses on low-pressure turbine blades at low Reynolds numbers. Experimental data collected using phase-locked particle image velocimetry and substantiated with a hot-film anemometer were used to answer fundamental questions about the influence of VGJs on a separated boundary layer. The data were collected on the suction surface of the Pack B blade profile, which has a non-reattaching separation bubble beginning at 68% axial chord. Two VGJ pulse histories were created with different frequencies, jet durations, and duty cycles. The mechanisms responsible for boundary layer separation control were …
Phase-Locked Piv Investigation Of The Effects Of The Blowing Ratio Of A Pulsed Vortex Generator Jet In A Low-Pressure Turbine, Nathan Michael Woods
Phase-Locked Piv Investigation Of The Effects Of The Blowing Ratio Of A Pulsed Vortex Generator Jet In A Low-Pressure Turbine, Nathan Michael Woods
Browse all Theses and Dissertations
At very high altitudes the Reynolds number flow through the low pressure turbine section of the gas turbine engine can drop below 25,000. At these low Reynolds numbers the flow is laminar and extremely susceptible to separation which can lead to increased losses and reduced lift. Small jets of air injected through the suction surface of the airfoil, called Vortex Generator Jets (VGJs), have been shown successful in suppressing separation and maintaining attached flow. Pulsing of these jets has been shown to be as effective as steady jets while reducing the amount of mass flow needed. An experiment using Particle …