Low-dimensional modeling of a mach 0.6 axisymmetric jet

This work looks to compare low-dimensional models of a Mach 0.6 axisymmetric jet taken from two independent velocity field data sets. The first is a large window PIV data set acquired at 4 Hz, and the second data set was acquired using time-resolved PIV sampled at 10 kHz. Both data sets are analyzed using the snapshot proper orthogonal decomposition technique to develop a better understanding of the most energetic structures in the flow field. From the large window PIV, the most energetic flow structures are seen to exist downstream of the potential core collapse and lower energy structures are seen to exist closer to the nozzle exit. Performing the same analysis on the time-resolved data set provides insight into a specific region of the flow field, but windowing effects are apparent when compared to the large window results. The advantage of using the time-resolved data set is that a time-resolved, low-dimensional model can be developed. Overall, each data set has strengths and weaknesses and the results of this work provides insight into how each of the data sets can be used to gain a better understanding of the high-speed jet flow field.