On this day in 1897, Charles G. Curtis was granted the patent for ELASTIC FLUID TURBINE. U.S. Patent No. 589,422.
The expanding-nozzles which have heretofore been used or proposed for converting the pressure of steam or other elastic fluid into vis viva and delivering it obliquely to the curved vanes of rotating turbines, by means of which the velocity is converted into mechanical power, have been provided with sides diverging to the points of delivery. it was discovered that this construction involves a considerable loss of power, due to the fact that if the proper conditions of expansion and conversion of pressure into velocity are produced at the delivery-point of the shorter side of the nozzle there is a still further and considerable expansion of the fluid at the point of delivery on the longer side of the nozzle, and that if the nozzle is proportioned to give the desired conditions at the central point of delivery there will still be a sufficient divergence from those conditions at the ends of the shorter and longer sides to produce a substantial variation from the proper velocity of flow at these points and consequent loss of power.
A further difficulty also arises from the fact that with the diverging nozzles as heretofore constructed or proposed the angle at which the moving stream of particles strikes the curved vanes is different on the two sides of the nozzle, being greater on the longer side, and hence the vanes to which the fluid-jet is delivered simultaneously receive a quantity of the fluid which diminishes from the shorter to the longer side of the nozzle, thus failing to deliver a sufficient quantity of fluid to some of the buckets to secure the maximum efficiency, and resulting in a further loss of power. It is especially important to overcome these difficulties in the case of compound turbines having long and complex passages,and that equal amounts of steam and at the same degree of expansion or pressure be delivered to all the passages through which the jet of steam flows, otherwise there may be very unequal ties of flow through the different vane-passages.
