Abstract
This study describes pressure drop characteristics at a rectangular elbow that a sudden contraction or a sudden expansion simultaneously occurs. This flow pattern can be found in high-density packaging electronic equipment. In order to predict flow pattern of cooling air in electronic equipment, an accurate prediction of airflow rate cannot be achieved by using conventional formulas for calculating pressure drop characteristics in simple ducts. This paper especially clarified the pressure drop characteristics at the rectangular elbows with the sudden contraction or the sudden expansion through the experiments. A relationship between the pressure drop and a change of the cross section area of the flow passage between an upstream side and a downstream side of the elbow was investigated. By using our experimental results, a prediction formula of the pressure drop was developed.
