ESDU 87015 presents design recommendations for various performance improvement methods such as vanes or splitters@ screens or perforated plates@ surface roughness or ribs cut transversely in the walls@ vortex generators@ truncation@ injection or boundary layer suction@ use of curved walls@ or the use of star-shaped inserts. Although the information on design and performance improvement is obtained from only limited ranges of test data drawn from the literature@ a tentative basis for interpolation or extrapolation is suggested. A tabular presentation summarising the methods and their advantages and limitations guides the user in selecting the most appropriate@ and a comprehensive worked example illustrates the use of the information.