Papers by Author: Kua Hai Yu

Abstract: Bending cyclic fatigue tests of 2D laminated C/C composites were conducted under load control at a sinusoidal frequency of 10 Hz. And three-point bending tests of fatigued specimens with various cycles were conducted at room temperature to evaluate the effects of cyclic load on mechanical properties. 2D C/C specimens were prepared by an isothermal chemical vapor deposition (CVD) process. The mechanical properties of composites were improved after cyclic loading at most the flexural strength by about 46% and the modulus 38%. The results show that the flexural properties of C/C composites were enhanced with the increase in fatigue cycles. It is suggested that the weakened interface between matrix and fibers by cyclic load play important roles in enhancing the property of C/C composites.

Abstract: A numerical based study was conducted to further understanding of turbine tip leakage and flow mechanisms for squealer tip blade. Three blade geometry models with different tips are established. They are squealer tip blade, squealer tip with injection holes blade, squealer tip with injection and film cooling holes blade, separately. Coupled aerodynamic and heat transfer numerical simulation method is used to study blade tip flow and heat transfer based the whole blade computational model. The results show that tip coolant injection will perform a positive effect for the resisting tip leakage, and it will reduce the temperature of blade tip surface and squealer rim, greatly. Film cooling near tip can cool blade squealer rim effectively, but it brings extra total pressure loss.