The 23rd Main Lecture to be given at a Branch Centre was also the First Henson-Stringfellow Memorial Lecture and was given at the Yeovil Branch on the 16th February 1956. Mr. D. L. Hollis Williams, F.R.Ae.S., Chairman of the Yeovil Branch, opened the meeting and the chair was later taken by Mr. E. T. Jones, C.B., M.Eng., F.R.Ae.S., Vice-President and President-Elect of the Society. The audience, which numbered some 400, included members of the main Society and some 50 members from the Bristol and Boscombe Down Branches

The prospect of sustained supersonic flight has, in recent years, greatly stimulated research on the many problems involving temperature and heat transfer which must be solved before this prospect becomes a reality. Aerodynamicists have been investigating the nature and intensity of the heat loading. Metallurgists have intensified their research on the properties of conventional materials, and they have been joined by physicists, chemists, and engineers in the quest for new materials of construction. Research on relevant structural problems has begun with a number of theoretical and experimental studies of structural components under thermal loading, and laboratories are now being prepared for the full-scale simulation of the thermal conditions predicted in supersonic flight.

The simplest case of asymmetric heating of a fluid flowing between parallel plates is considered. This occurs when heat is transferred to the fluid through one plate, the other being adiathermal. For a theoretical analysis, it is convenient to assume fully developed flow in a parallel channel of infinite aspect ratio, this condition being not widely different to that met with in practical applications.

The results are presented of an investigation of a particular type of baffle for the production of symmetrical velocity profiles having high ratios of maximum to mean velocity in ducted incompressible flow. Two similar families of profiles are obtained depending on whether a short (12 diameters) or a long (48 diameters) entry length is used before the baffle. The highest value of the maximum to mean velocity ratio obtained is 1·42 and the pressure loss coefficients associated with the use of the baffle are given together with an indication of the effect of Reynolds number.