This article describes the design and performance testing of a turbine bypass valve trim. For effective control of velocity and pressure, a trim designed to have a tortuous path was designed. Computational fluid dynamics and FEM analyses were used in the design process. The valve, which was installed the designed trim, was tested. To evaluate its performance in the field, the valve was installed at a 900 MW combined power plant system for three months. The results showed that the pressure letdown was successfully controlled by the designed trim, and the noise level was reduced by about 8.1 per cent compared with the previous trim-type valve.

The authors present a theoretical investigation on the sputtering of a Cu solid by SiCl4 molecules. The classical trajectory method is used to calculate Cu atom sputtering yields, degrees of anisotropy, kinetic energy distributions and angular distribution for collisions energies up to 1000 eV. The only products of the sputtering process are Cu atoms. However, CuCl molecules do form on the surface. Results for Ar+ ion sputtering of the Cu solid are also reported for comparison with those for SiCl4. It is found that the etching yield for the SiCl4 molecules at energy E is close to five times that for Ar+ at energy E/5. This is because the SiCl4 molecule dissociates on impact to give five individual atoms.