The effect of duct Mach number upon the acoustic reflection coefficient at the inlet of a duct with mean
flow is investigated. An analysis, which models the duct inlet as a very short, one-dimensional nozzle over
which the mean flow is accelerated from rest, gives good agreement with some recent experimental results.
Discrepancies between the analysis and the experimental results are discussed in terms of radiation losses at
the inlet and real fluid-flow effects within the duct
