SPRENGER

SWITZERLAND (see also List of Individuals)

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29.6.1911 Basel/CH - 19.11.1997 Zürich/CH

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Herbert Sprenger was a German born in Basel. He graduated as a mechanical engineer from ETH Zürich in 1937 and for the following two years was an assistant of the ETH Aerodynamic Laboratory then directed by Jakob Ackeret (1898-1981). During World War II Sprenger was then a research associate with Escher-Wyss in Zurich and from 1947 was again at the Aerodynamic Laboratory of ETH, where he stayed until retirement in 1977.

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Sprenger's career was determined by Ackeret. The latter was appointed professor of aerodynamics in 1931 after having been a collaborator of Ludwig Prandtl (1875-1953) at Göttingen University. Sprenger's main interests were energy losses in hydraulic elements. He thus investigated during his PhD dissertation diffusers of various geometries including straight and curved axial arrangements. He not only observed the pressure loss but attributed it to a modification of the velocity field across the diffuser. Later, similar results were elaborated for curved ducts of a variety of shapes. It was found that the head loss coefficient depends on cross-sectional shape and in addition on the Reynolds number of the approach flow. The latter effect may only be ignored for Reynolds numbers in excess of some 105. Sprenger as Ackeret were remarkable hydraulic experimenters and introduced a number of original probes to measure hydraulic characteristics. They also employed dye in fluid flow to portrait a certain flow field. Elements to reduce pressure losses such as vanes were also systematically investigated. Sprenger's 1971 work relates to the aerodynamic design of an university auditorium including the tables through which the air was supplied, and the correct air take-off in order that oxygen supply was almost uniformly distributed in the auditorium along with a minimum of noise load.

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_{Detra, R.W. (1953). The secondary flow in curved pipes. Mitteilung 20. Institut für Aerodynamik, ETH: Zürich.}

_{Sprenger, H. (1959). Experimentelle Untersuchung an geraden und gekrümmten Diffusoren. Dissertation ETH 2803. Leemann: Zürich.}

_{Sprenger, H. (1969). Druckverluste in 90°-Krümmern für Rechteckrohre. Schweizerische Bauzeitung 87(13): 223-231.}

_{Sprenger, H. (1971). Experimentelle Strömungsuntersuchungen im Versuchsauditorium der ETH Zürich. Gesundheits-Ingenieur 92(8): 225-231.}

_{Sprenger, I. (2004). Herbert Sprenger. Personal communication. P}