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A simulation model is utilized to predict the performance of a high temperature water‐to‐water heat pump, running on Refrigerant 11, over a range of evaporator and condenser water temperature (10 to 40°C and 40 to 70°C) and compressor speeds (500 to 3000 r.p.m.). It is shown that heat pump power output can be effectively controlled by varying compressor speed. Effects of compressor speed, heat source and heat sink (end‐use) temperature on the heat pump efficiency are presented. Special attention is devoted to the values of predicted refrigerant temperature at the compressor discharge. These are compared with the thermal limit of the refrigerant. Modifications to the system, to reduce refrigerant maximum temperature, are also discussed.

The performance of a radial flow turbine, operating on compressed air, is measured over a range of pressure ratio and speed. Separate tests on the nozzle assembly alone enable the rotor performance to be separated from the overall characteristics. In particular, the conditions at each pressure ratio for which the nozzle exit whirl velocity is equal to the rotor tip speed may be deduced. Also, it is possible to evaluate the enthalpy ‘loss’ in the rotor, that is, the difference between the specific enthalpy drop actually occurring in the rotor and its isentropic value. An attempt is then made to relate this loss with the relative velocities within the rotor passages as predicted by inviscid, two-dimensional analytical techniques. The method developed by Stanitz and co-workers has been programmed to analyse the rotor internal fluid flow properties in the blade-to-blade plane for the conditions of zero incidence. The region investigated does not include the whole rotor, but extends from a boundary upstream of the blade tip to a downstream boundary at a radius equal to 72 per cent of the tip radius. The analysis is performed for overall turbine static to static pressure ratios of 1·2 to 1·6. The result of the theoretical analysis is to show that the variable ratio of rotor outlet to inlet specific volume with changing pressure ratio is accommodated almost entirely without any change in the flow distribution; that is, over the region of the impeller investigated, and at overall turbine pressure ratios up to 1·6, the compressible flow through the rotor may be considered as being through stream tubes of fixed geometry. There is thus a sound basis for the correlation of rotor loss coefficient in terms of parameters which describe compressible flow with friction along variable area pipes. Consideration is given to the manner in which the zero incidence loss coefficient may be defined in order to remain constant at varying pressure ratios.

The current state of a research program to study flows in radial turbomachines at both on- and off-design conditions is described. Numerical solutions of the flow within a rotating impeller are described based on potential theory using a direct method of solution instead of by relaxation. The experimental apparatus comprising a rotating cascade rig is described. The rig consisted essentially of a rotor mounted horizontally in an open circular water tank. An external pipe system enabled the water to be circulated for either radial inflow or radial outflow. The rotor speed could be varied up to 300 rpm. A variety of perspex shrouded rotor geometries up to a maximum diameter of 3 ft 6 in could be tested. Flow visualization by means of polystyrene particles could be observed by a camera mounted above the rotor on its axis and driven at the same angular speed. A 12-channel electronic flash unit enabled the particle velocity and directions to be photographed. As an alternative to the flow visualization system, a bank of manometers, could be mounted above the rotor and driven at the same rotational speed, i.e., with no relative movement. Static pressure measurements could be taken on the blade faces and within the rotor passages. A comparison is made of the experimental and analytical results obtained for one straight vaned, constant area rotor.