Spectral analysis of LDV measurements inside of the TAMU air-cooled reactor cavity cooling system

Spectral analysis was applied to the LDV measurements inside of the TAMU air-cooled RCCS facility at two different locations to both evaluate the feasibility of spectral methods for this experiment and gain a first insight into the flow behavior using a Fourier representation. Application of the wavelet transform showed that there are patterns in the flow signified by repeating frequencies and flow structures. Although the sampling rate of 7.92 Hz at the data point centered at the bottom center of riser 4 was lower than the higher frequency sampling rate of 57.92 Hz at the top data point of the upper plenum, the wavelet transforms of the higher frequency data point showed that the dominant frequencies were bounded within 4 Hz. Application of wavelet analysis is limited by the size of the interrogation window but may be modified according to the frequency range of interest by adjusting the size of the time width for the undilated Morlet mother wavelet. Spectral analysis can be applied to future experiments to understand uncharacterized flow behavior such as flow reversal inside of the upper plenum and for benchmarking future CFD simulations.

Spectral analysis of LDV measurements inside of the TAMU air-cooled reactor cavity cooling system Conference Paper