Shannon entropy characteristics of two-phase flow systems

A method to calculate Shannon entropy of two-phase flow systems from the power spectral density of the output signal is introduced in this article. Two series of experiments are made successively. One is used to investigate the density wave instability in a test facility to study the Chinese 200 MW nuclear heating reactor. After studying the Shannon entropy of the inlet pressure drop in all 534 experimental tests under different heating power, inlet subcooling, operating pressure, and inlet orifice resistance, we find that tests with higher negative Shannon entropy (negentropy) are unstable while those with lower negentropy are stable, like energy used in many fields. The other experiment was made to research two-phase flow regimes in vertical pipes. We calculate the time-dependent negentropy of the air-water flow through the power spectral density of the pressure drop. From the results, we find that the negentropy of the bubble flow is the smallest, the slug flow's negentropy is the largest, and the negentropy of the annular flow is between the bubble flow and annular flow. (C) 1999 American Institute of Physics. [S0021-8979(99)07411-3].