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e Banki Water Turbine

By
C. A. MOCK MORE Professor of Civil Engineering
and
FRED MERRYFIELD Professor of Civil Engineering

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I. INTRODUCTION


1. Introductory statement. The object of this Bulletin is to present a free translation of Donat Banki's paper "Neue Wasser-turbine," and to show the results of a series of tests on a laboratory turbine built according to the specifications of Banki.
The Banki turbine is an atmospheric radial flow wheel which derives its power from the kinetic energy of the water jet. The characteristic speed of the turbine places it between the so-called Pelton tangential water turbine and the Francis mixed-flow wheel. There are some unusual characteristics not found in most water wheels which are displayed by the Banki turbine and should be of interest to most engineers, especially those of the Mountain States.
Included in this bulletin are diagram's of two Banki turbine nozzles as patented and used in Europe.

II. THEORY OF THE BANKI TURBINE
1. Description of turbine. The Banki turbine consists of two parts, a nozzle and a turbine runner. The runner is built up of two parallel circular disks joined together at the rim with a series of curved blades. The nozzle, whose cross-sectional area is rectangular, discharges the jet the full width of the wheel and enters the wheel at an angle of 16 degrees to the tangent of the periphery of the wheel. The shape of the jet is rectangular, wide, and not very deep. The water strikes the blades on the rim of the wheel (Figure 2), flows over the blade, leaving it, passing through the empty space between the inner rims, enters a blade on the inner side of the rim, and discharges at the outer rim. The wheel is therefore an inward jet wheel and because the flow is essentially radial, the diameter of the wheel is practically independent of the amount of water impact, and the desired wheel breadth can be given independent of the quantity of water.