STG-19 Design Guidance for Impingement Rods
Impingement rods are more effective than plates in protecting entrance tubes from damage. HTRI developed a method to assess the relative impact of a variety of competing flow conditions produced by each impingement configuration. For the conditions established in this study, a two-row grid of rods with a diameter slightly smaller than the tube and positioned about 1/3 of the nozzle diameter below the nozzle/shell junction performs best. The method, as described in this report, was implemented as a default in Xist 7.1.