Thermographic Investigation on Fluid Oscillations and Transverse Interactions in a Fully Metallic Flat-Plate Pulsating Heat Pipe

The present investigation deals with the quantification of fluid oscillation frequencies in a metallic pulsating heat pipe tested at varying loads and orientations. aim is to design robust technique for study inner dynamics without adopting typical experimental solutions, such as direct visualizations through transparent inserts. studied device made copper, it partially filled water–ethanol mixture (20 wt.% ethanol). Heat fluxes locally exchanged between working walls are first assessed inverse conduction problem resolution approach by processing outer wall temperature distributions acquired thermography. estimated local transfer quantities therefore processed quantify oscillatory behavior every branch during intermittent flow full activation regimes, thus providing deeper insight into modes. After dealing further validation terms frequency restoration capability, wall-to-fluid referred each channel means wavelet method. Scalograms power spectra considered signals presented time-based analysis oscillations, well identification dominant frequencies. Fluid motion then quantified continuity oscillations activity channels applying scalogram denoising named K-means clustering Moreover, statistical reduction channel-wise performed provide useful references interpretation overall behavior. link transverse interactions finally investigated. vertical bottom-heated mode exhibits stronger respect horizontal mode, ranging from 0.78 up 1 Hz. Nonetheless, more stable when operates orientation probably due negligible buoyancy effects. thermal adjacent found be presents similar features orientation. proposed method analyses fully flat-plate pipes can effectively adopted other layouts any need windows, reducing complexity set-ups providing, same time, good dynamics.