Abstract:

ESDU 76018 compares seven recognised prediction methods with a very large range of experimental results taken from the literature. By means of a statistical analysis, performance charts are developed that show for a number of ranges of both liquid volume fraction and mass velocity the order of ranking of the prediction methods in accuracy and the likely errors involved for each method within those conditions. As a result the best prediction method is recommended for any practical set of conditions, ensuring that the best prediction of gradient can be made and the accuracy of prediction can be assessed. The methods are Lockhart and Martinelli, Martinelli and Nelson, Thom, Baroczy, Chenoweth and Martin, Chisholm, and simple homogeneous theory.