No abstract

In order to improve efficiency in turbomachinery, brush seal replaces labyrinth seals widely in the secondary air system. A 2-d staggered tube bank model is adopted to simulate the gas states and the pressure character in brush seal, and computational fluid dynamics (CFD) is used to solve the model in this paper. According to the simulation results, the corrected formula of the Euler number and dimensionless pressure are given. The results show that gas expands when flow through the bristle pack, and the gas expansion closes to an isotherm process. The dynamic pressure increases with decreasing static pressure. The Euler number can reflect the seal performance of brush seals in leakage characteristics. Compared with increasing the number of rows, the reduction of the gap is a higher-efficiency method to increase the Euler number. The Euler number continually increases as the gap decreases. However, with the differential pressure increasing, Euler number first increases and then decreases as the number of rows increases. Finally, the pressure distribution on the surface of end rows is asymmetric, and it may increase the friction between the bristles and the back plate.

Methane was widely used in many combustion systems. The premixed flame propagation in a chamber was a typical deflagration process. To explore the complicated gas deflagration mechanism in combustion system, it is necessary to discern flame propagation characteristics of gas fuel in a certain combustion chamber. Combustion dimension plays an important role in flame propagation behavior, therefore a model of different aspect (L/D) ratio chambers filled with premixed methane-air were performed to explore the flame propagation behavior. Based on numerical simulation results and theoretical analysis, the corresponding propagation characteristics such as pressure changes and temperature changes were obtained, which shows that the larger L/D Ratio of combustion chamber was, the greater flame speed and pressure, which mainly due to the less loss of heat and adiabatic compression of the high-temperature burnt gases.

No abstract

We developed a real-time software for CEST post-processing and visualization on Philips 3T scanner, termed as PV-CEST. PV-CEST runs in the vendor provided PRIDE 2.0 environment, providing image view, Z-spectra analysis and quantitative maps calculation functionalities during scanning procedure, which could have great clinical utility.