Alvin Peterka—Hydraulic Engineer

Abstract

An energy dissipator is a hydraulic structure used to convert hydraulic energy mainly into heat. These dissipators have a relatively short history because they were developed only after damage had occurred at the toe of overflow structures. The German Theodor Rehbock ~1864–1950! conducted the first detailed research into these structures, although hydraulic jumps had received attention as early as the 1820s by the Italian Giorgio Bidone ~1781–1839! by imposing constant energy head across the hydraulic jump. In 1838, Jean-Baptiste Belanger ~1790–1874! correctly applied the momentum equation for the prediction of sequent depths, and Henry Bazin ~1829–1917! verified this concept with limited observations. Nothing much happened until around 1910–1920 when Arnold Gibson ~1878–1959!, the successor of Osborne Reynolds at Manchester University, presented experiments that corroborated the predictions of Belanger. That concept obtained final acceptance by the 1916 paper of the American Karl R. Kennison ~1886–1977!, whose closure verified data of various sources ~Hager 1990!. At about the same time, Rehbock proposed his ‘‘dentated sill.’’ It was later realized that this device mainly deflects remaining bottom currents to the free surface and thus inhibits scour downstream of the end of the stilling basin. The development of stilling basins was then continued mainly by the Austrian Armin Schoklitsch ~1888–1969! with his two books ~Schoklitsch 1930, 1935! and by Hunter Rouse ~1906–1996! from the conceptual side by introducing the Froude number as the significant parameter for all quantities of that phenomenon ~Rouse 1934!. In 1933, the International Commission of Large Dams ICOLD was founded with exponents such as Andre Coyne ~1891–1960!, who in the late 1930s proposed the ski jump type dissipator as an alternative to the conventional hydraulic jump dissipators. The latter continued to be a standard design mainly for relatively small velocities up to a maximum of about 20 m/s and inflow Froude numbers essentially between three and six. A number of elements had been proposed to reduce the length of the stilling basin but without a definite consideration of the various pros and cons. By the end of World War II, hundreds of different types of energy dissipators were available, partly developed for particular site conditions and partly presented as an engineer’s design from the office table. What was definitely missing was a thorough scientific consideration of energy dissipators under a wide variety of flow conditions and proposals relating to engineering applications. Here, Peterka has contributed significantly and was even able to come up with a series of standard designs to be applied under well-defined flow conditions without the need for additional observations. The engineering community thus derived a great benefit from his services. For completeness, the contributions to that subject by Fred W. Blaisdell ~1911–1998!, of the Saint Anthony Falls Hydraulic Laboratory should also be mentioned.