Design and Performance of Vaneless Volutes for Radial Inflow Turbines: Part 2: Experimental Investigation of the Mean Line Performance—Assessment of Empirical Design Parameters

The non-dimensional design procedure described in Part 1 assumed a one-dimensional compressible flow and as such relied on the empirical specification of the dissipation of angular momentum, the dissipation of energy and the deviation of the swirling flow from that of a free vortex. This was based largely on data available in the published literature. In order to develop and substantiate the empirical procedures further an experimental study was carried out in parallel with the development of the design procedure.

The experimental investigation described here had the specific objective of assessing and developing appropriate empirical models and coefficients for application to the design procedure. The study concentrated on the application of a five-hole probe located in the centre of the volute passage and at a series of azimuth angles around the discharge. The probe provided stagnation and static pressure measurements, from which the gas velocity was derived, together with the flow angle. When taking measurements at the volute discharge a stationary dummy rotor was used to carry the five-hole probe.