Calendar: 1973-1974 Page 435

lxii Annual Report of the Delegacy the emission from engine exhaust systems in the form of particulates is being studied in association with an industrial research laboratory The investigation into the mixing between two streams of powder flowing down an inclined chute has continued and this work is now supported by contract from the Department of Trade and Industry The results are most interesting and suggest new and effective method for the continuous mixing of free-flowing powdered materials paper on the work was read at Symposium organised by the London and branch of the Institution of Chemical Engineers at Imperial College in January Other investigations in powder technology are proceeding satisfactorily In the refrigeration field research student was awarded the degree of Ph for work concerned with the cooling effects produced by vortex tube Research into two-phase flow in evaporators is proceed- ing Measurements of pressure drop and local heat transfer coefficient are being made with the aim of optimising the design of refrigerant evaporators In regard to the project outlined last year which is directed at measuring the enthalpy gains through the doors of cold stores measurements have shown the validity of relatively simple theory for constant opening The extension of this to intermittent openings is continuing Research on air movements in small radial in-flow turbines is also proceeding This arises from the need for detailed knowledge in order to approach design problems systematically The interaction between rotor and stator produces very complex flow and instrumentation is difficult because of the high rotational speed of the rotor 80 000 In the work under review-which is supporting- three geometrically similar rotors have been manufactured with blade tolerances of ο 001 This is very satisfactory in view of the complex shapes involved In the first part of the investigation the turbines will operate under steady flow conditions and it is hoped to compare the results with those predicted by inviscid flow theory In the tribology field research on the wear testing apparatus is continuing and promising results have been obtained During the session members of staff took part in number of conferences and symposia Dr Vinnicombe again visited Danfoss in Denmark where he conducted seminar for senior designers on 'Tribology Considerations in Hydraulic Machinery Design' Dr English visited the works of Weserhiitte Otto Wolf GmbH at Bad Oeynhausen Germany to study design and production methods