Analysis of transient pressure and temperature variations in a subcooled boiling channel under forced vertical excitations

Abstract

In this paper, an experimental facility of a subcooled boiling flow loop with a vertical exciter has been constructed and tested to investigate the transient variations of subcooled boiling flow parameters under forced excitations. Various heat fluxes (q= 6204 and 11029 W/m2) were loaded to the test section under stationary and different forced excitation conditions f= 0, 0.51, 1.06 and 1.62 Hz). The transient signals of differential pressure (DP) and fluid temperature were recorded during the tests, and the fast Fourier transform (FFT) was utilized to analyze the transient data. It was observed that under low frequency excitations (f= 0.51 Hz), the variations of pressure and temperature due to forced excitations were relatively minor and may not be clearly identified by the FFT. Whereas in higher frequency excitations f= 1.06 and 1.62 Hz), the excitation frequencies can be clearly shown in FFT results, which suggests that the flow can be oscillated and the transient variations were observable under the higher frequency forced excitations.