Evaluation of affected region by steam jet on surrounding environment

If a piping system under high pressure is damaged and steam is ejected into the atmosphere, human safety and safety equipment may be damaged by the impingement of the steam jet. Therefore, it is necessary to evaluate the region affected by the steam jet impinging on the surrounding equipment and people. This study is conducted to identify the problems with the evaluation model of the region affected by the jet specified in the ANSI standard and to reconstruct the evaluation model of the affected region based on the experimental results. From the visualization experiment and CFD analysis results, we found that the ANSI standard can be used to appropriately evaluate the experimental and CFD results for the steam spread angle and asymptotic plane area. On the other hand, the results of asymptotic length were different from the experimental and CFD results owing to the assumption in the ANSI standard that the expanding angle of the steam jet is constant at 45° regardless of any pressure change. A correlation equation for the expansion angle of the steam jet caused by a pressure change was developed referring to the experimental and CFD results, and the improved model was used to evaluate the asymptotic length. By using this improved model, it is possible to evaluate the region affected by the steam jet in the event of pipe failure, under a wide range of pressure and nozzle conditions. (author)