The Steam Turbine. (Including Appendixes and Plate).

Abstract

THE first turbine-engine of which there is a record is that of Hero of Alexandria, about 130 B.c., a reaction engine or steam reaction wheel. The next is Branca's paddle-wheel (about 1629), impelled by a steam-jet. The .principles involved in these designs of turbines are practically identical ; and the peripheral speeds for equal efficiency would require to be about equal. I n neither of them was the utilization of the expansive energy of the steam carried beyond that obtained in the course of its issue from a non-divergent jet ; nor was the construction of the machine calculated to stand a speed of rotation high enough to afford B reasonable return in power for the steam consumed. The earliest patents for steam-turbines began to be filed towards the end of the eighteenth century ; but excepting Watt's proposed rotary engine of 1784, in which the principle now familiar in the pulsometer was applied to force water through a Barker wheel, there appeared in them no substantial advance towards the construction of an economical turbine-engine till the year 1837, when William Gilman first suggested the compound turbine. I n his design this took the form of several Barker reaction wheels mounted on a common shaft, and operated by steam in separate cases ; the steam traversing the wheels in series, and the apertures in the successive wheels increasing in size to allow for and to utilize the expansion of the steam. He also described a Barker wheel surrounded l~y an oppositely rotating ring of buckets, the wheel and bucket-wheel transmitting power through bevel-gearing to a common shaft. I n 1838 Matthew Heath enunciated for the first time the principle of the diverging conical nozzle for converting the expansive energy of the steam into kinetic energy. Heath was under the impression that in an ordinary jet the whole of the expansive energy of the steam is lost. This is not the case ; but his diverging expansive tube, though shown in his drawings of exaggerated pro-Downloaded by [ Newcastle University] on [25/09/16].

Fundamentals, biomedical applications and future potential of micro-scale cavitation-a review

“…Surface tension, viscous forces, and Marangoni stresses in micro-orifices provide major reasons for these differences. 18 Furthermore, the electric double layer has been also observed in some experiments due to the attraction between the surface charge and ions of the fluid. 24,25…”

“…This section provides an overview of bubble nucleation theory in microfluidics systems and parameters, which affect cavitation inception in micro-scale. Parsons 18 recognized the vaporization role in the emerged bubbles and wakes for the first time in 1906. Since then, the cavitation phenomenon has been the subject of extensive research efforts.…”

Cavitation inception of a van der Waals fluid at a sack-wall obstacle

“…This phenomenon causes noise, vibrations and above all it can significantly affect the performance and damage the solid structures (cavitation erosion 3 ) of engineering devices. Despite the passing of more than one century since the first studies of Reynolds 5 and Parsons 6 on the effects of cavitation on ship propellers, a comprehensive understanding of the physics of the phenomenon is still lacking as its analysis is challenging from both an experimental and a numerical point of view.…”