Early Historical Development of the Centrifugal Impeller

Abstract

The centrifugal impeller has been in existence for over two hundred years but its perfection and rapid development occurred only in the last sixty years. This paper deals with the early development of the centrifugal impeller in the last and early this century. The centrifugal impeller is found in centrifugal pumps and compressors. Next to the electric motor, centrifugal pumps and compressors are believed to be the most widely used machines of our time. The field of application of these rotary machines has been continually widening, as they are developed for handling a wider range of liquids and gases at higher pressure and greater temperatures, and whole industries become more and more dependent on them. The first centrifugal impeller with ten wooden double curved blades and dating back to the fifth century was found in 1772 in an abandoned Portuguese copper mine in San Dominigos. Centrifugal fans had been used for mine ventilation as early as in the sixteenth century. The invention of the centrifugal impeller is a disputed issue whether the credit goes to Leonardo Da Vinci (1452–1519), who suggested the idea of using centrifugal force for lifting liquid, or to Johann Jordan about 1680. Most place the origin of the centrifugal impeller with Denis Papin in 1689. The importance of Papin’s contribution lies in his understanding of the concept of creating a forced vortex within a circular, or spiral casing by means of blades. Following Papin, Kernelien Le Demour in 1732 and Daniel Gabriel Fahrenheit in 1736 described other designs for centrifugal impellers, but there is no evidence of their practical use. Euler presented in his 1754 memoir an idealized theoretical application of Newton’s law to centrifugal impellers, based on a conceptualization of his tubular turbine run backwards and now universally known as the “Euler equation”. His publication caused a great development of hydraulic turbines in the eighteenth century, but did little to influence the development of centrifugal impellers, which had to gradually develop through tedious cut-and-try methods. The one thing Euler contributed was to initiate a true mathematical inquiry into the employment of centrifugal force as a means of raising fluid. About the same time as Euler, John Smeaton introduced in 1752 the study of turbomachinery by models. He also defined power as equivalent to the rate of lifting of a weight, a concept that is still fundamental in thermo-fluids. Today both centrifugal pumps and compressors have reached efficiency levels above 90% and are built in sizes from a few Watts to Megawatts. This paper traces the early historical development of the centrifugal impeller. Factors that promoted and hindered the early development are also discussed.