Chaotic Dynamic Characteristics Analysis of a Single-Loop Pulsating Heat Pipe under Different Influencing Factors

The chaotic characteristics of working fluid flow and heat transfer in pulsating heat pipes are investigated in this study by means of nonlinear dynamics methods.By analyzing wall temperature time series signals and combining characteristic parameters including power spectrum, Lyapunov exponent, and chaotic attractors, the chaotic behavior characteristics of the system under stable operation are revealed.The result shows that wall temperature fluctuations presents chaotic motion intermediate between periodicity and randomness, and increasing the heating power enhances the system’s chaotic characteristics.Distribution pattern of attractors is obtained by using the nonlinear analysis methods based on phase space reconstruction.The distribution characteristics of chaotic attractors can in turn effectively reflect the amplitude and frequency of temperature oscillation as well as the operational stability of the PHP, and the optimal delay time derived from the spatial distribution of attractors is thus determined as τ =7.The influences of such factors as heating power, heating wire length ratio and filling ratio on the attractor trajectory are investigated in the present study,and analyzes the intrinsic relationship between the attractor distribution, operation trajectory and the operational process of pulsating heat pipes, which facilitates the state identification, optimal control，fault diagnosis，and other aspects of operational process management.