A STUDY ON THE BEHAVIOR OF A CRACK LOCATED AT THE STRIPING ZONE IN A THERMALLY STRATIFIED PIPE

Abstract

The behavior of a small crack located at the thermal striping zone in a thermally stratified piping is numerically investigated. The effects of the parameters such as fluctuation frequency/amplitude of the density interface, heat transfer coefficient near the thermal striping zone, and crack depth on the behavior of the crack are examined to identify the governing parameters. The effect of the contact surfaces on the stress intensity factor range is also examined for several levels of the internal fluid pressure. The stress intensity factor range, DELTAK(I), is used to describe the crack behavior due to the thermal striping. The findings of the numerical investigation are as follows: (1) the value of DELTAK(I) increases up to a specific Fourier number and then decreases beyond the specific Fourier number. (2) With the increasing Biot number the value of DELTAK(I) increases and the Fourier number(Fo) at which the DELTAK(I) vs. Fo curve has a peak decreases. This means that the behavior of a crack located at the thermal striping zone has a large dependence on the oscillating frequency of the density interface and the heat transfer coefficients. (3) The value of DELTAK(I) increases up to a specific crack depth and then decreases beyond the specific crack depth. (4) If the fluid pressure is lower than a specific value, the value of DELTAK(I) decreases because of the crack surface contact.