Constructability of Full-Depth Precast Deck on a Steel Girder Bridge with Injection Channel Connection

In this study, the constructability of a full-depth precast deck installation on a steel girder bridge with injection channel connection was evaluated. This type of girder has been developed to avoid the overlap between the shear studs and the bridge deck, which is a major issue causing delays in modular construction. First, the optimal dimensions and lifting method for the deck were determined through finite element analysis. Subsequently, the constructability of deck installation on the bridge was evaluated with various radii of curvature using building information modeling (BIM). For the efficient use of BIM, algorithm-based models for the girder and deck were developed to change their shapes easily.

Y. S. Hu, H. J. Wei, B. Yu, O. X. Yang, J. Wang, J. Wu. Research on the vapor injection of two-stage rotary compressor / trans. from Engl. M. A. Fedorova

In order to understand the vapor injection flow characteristics of two-stage rotary compressor in the course of compression, a mathematical model based on mass conservation equation, energy equation and thermodynamic identity was established and proved by P-V diagram testing results. Some useful conclusions about pressure in the intermediate chamber and mass flow of vapor injection in the course of compression were also given out. The results show that, gas backflow between the intermediate chamber and the vapor injection channel is an important defection of two-stage rotary compressor which can be solved by the application of injection valve in vapor injection channel. The injection valve can obviously reduce the gas backflow and the power loss in the course of compression while increasing the pressure fluctuation in the intermediate chamber. Experiments show that the COP of two-stage rotary compressor with the injection valve increased by over 2% in ASHRAE/T working condition.

Mixing Enhancement With Rotating Ramps in a Scramjet Engine

A concept of mixing enhancement forced by rotating ramps has been presented, which based on the design of stationary ramps and Rim-Rotor Rotary Ramjet Engine. The commercial software Fluent has been conducted to study the nonreacting flowfields in a transverse hydrogen fuel injection channel. The results indicate a slowly increased mixing efficiency when the ramps speed increase. As the ramps rotate at a speed of 6000rpm, the mixing efficency is almost the same as the stationary ramps case. As the ramps rotate at a speed of 54295rpm, a 10%∼20% higher mixing efficiency is obtained.

Three Dimensional Numerical Analysis of Plasma Spraying Using Supersonic Plasma Gun

Numerical method is applied to analyze the spraying process using supersonic spraying gun; special attention is paid to temperature and velocity fields of argon plasma flow, including. In term of plasma properties, ionization and recombination of plasma species are taken into consideration. The impact of internal injection channel on main plasma gas flow, both velocity and temperature, are investigated. With full dimensional model, three dimensional properties of plasma flow and internal injection channel impact are revealed.