Numerical Evaluation of Rotordynamic Coefficients for Compliant Foil Gas Seal

Compliant foil gas seal is one of the advanced cylindrical gas seal technologies and can be commonly used in the secondary flow system of an aero-engine. It can enhance the dynamic stability of the aero-engine by meeting the steady requirements of the aero-engine seal system. To evaluate the performance of compliant foil gas seal, the steady performance of the gas seal is firstly analyzed to predict the sealing efficiency and obtain the pressure distribution of the gas seal in the compressible flow field. Then, the effects of the operating parameters on the rotordynamic coefficients are analyzed using the finite differential method. It can be used to predict the operation performance of the aero-engine and prepare for the optimization and test rig of compliant foil gas seal on the T-shaped groove.

Analysis of Operability Envelopes for Subsea Production Tree Installation

The article presents a mathematical model to investigate the operability envelopes for subsea production tress (SPT) installation using drill pipe. The finite differential method was used to solve the established governing equations in which the ocean conditions were considered. Based on the evaluations of the ocean wave, ocean current, water depth, specification of drill pipe and SPT weight that might dominate the mechanical behaviors of the pipe, the operability envelopes with permissible ocean conditions for SPT installation were obtained. The results indicate that changes of depths in deep water and SPT weight have few effects on the operation conditions and it would be better to choose smaller pipe to obtain larger permissible ocean conditions during SPT installation.

Numerical Simulation of Temperature Field during the Growth of Nd:GGG Laser Crystal

The numerical simulation research on temperature field of crystal and melt by using finite differential method during the growth of Nd:GGG crystal by Cz (Czochralski) method was reported. At first, the mathematical model of the growth of Nd:GGG crystal was given, then the equations without dimensions were given. Finally, the boundary condition was given and the equations were solved by finite differential method. The simulation program was given by above method.Then the change of temperature field of crystal and melt was described by simulation program. The influence of technical conditions of temperature field in the crystal and melt was analyzed.