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After running for about 59 000 h, the tubes at the intermediate mixing header of the furnace water wall leaked in an ultra-supercritical boiler. Preliminary analyses show that the primary crack may be initiated from two kinds of crack. One kind of crack is the dense transverse cracks in the external walls of the fireside, and the other one is the crack in adjacent H-shaped fin fillet weld. In order to figure out the initiation of the primary crack, the macroscopic morphology, chemical composition, microstructure, Vickers hardness and fracture morphology observation were conducted on the sample tube. The oriented dimples in the primary crack indicate that the crack propagates from the external side to the inner side. The erosive metal loss at fireside surfaces of tubes adjacent to the initial cracking shows significant differences. It is indicated that the primary crack is initiated from one side connected with the H-shape fin fillet weld crack. Based on comprehensive analyses of material quality of the sample tube and boiler operation data, it can be concluded that the wall temperature of water wall tubes changes with the frequent and large fluctuation of boiler load due to peak regulation operation, which is the root cause of fatigue cracking of H-shape fin fillet weld.

Inclined multi-hole full-coverage film cooling, as a practical cooling scheme, has received widespread application in combustion chambers. In the initial stage of combustion chamber design, the numerical simulation of three-dimensional structure is a long calculation period. A simple one-dimensional program can shorten the design cycle, which is used to preliminaries calculate heat transfer characteristics and flow distribution. A simple temperature calculating method of inclined multi-hole wall temperature in the high temperature combustor flame tube was developed. The flow and heat transfer characteristics in the combustor can be expected by this method. Heat transfer in the combustor flame tube is researched based on the plate flow field. The coupling effects of heat transfer, wall heat conduction and radiation heat transfer are considered, such as convective and Radiative heat transfer between primary flame flow and the hot wall side, convective heat transfer in the film holes, convection and radiative heat transfer between the cool wall side and the annular cooling air flow, radial heat conduction inside the wall. In the initial stage of combustion chamber with inclined multi-hole design, the design cycle can be shortened by this method, using relatively simple calculation to know the combustion chamber wall temperature. Keywords: Combustion chamber, Inclined multi-hole, Film cooling, Wall temperature, Flame tube

A novel ATGS-PVDF composite film has been fabricated by exerting an external electric field on the composite during preparation. XRD spectra of the films indicate that they have high orientation ratio along the external electric field. The permittivity, pyroelectric coefficient and the pyroelectric figure of merit increase with the applied field.

The growth rate of modified TGS (ATGSP) crystal has been increased from 1mm/day to 5mm/day by increasing the stability and quickening the convection of the solution. The pyroelectric, dielectric and ferroelectric properties of the rapid growth ATGSP crystals have been measured. The quality of the crystal is good. The pyroelectric figure of merit of ATGSP crystal grown by rapid growth rates is the same as that of slow growth crystal. However the rapid growth crystal has more L-alanine content and lower tan δ than that of the slow growth crystal and it has very high bias field (Eb).