Johann Stumpf (engineer)

Johann Stumpf of the Charlottenburg Technical College in Berlin is best known for popularising the uniflow steam engine, in the years around 1909, and his name has always been associated with it. The basic uniflow principle had been invented many years before. 
Idea.
Stumpf's 'Uniflow' system aroused interest among engine designers in the years before the First World War, at first in his native Germany and later elsewhere. The Uniflow principle was known previously, and Stumpf's work was really its practical application. In Stumpf's system steam was admitted at one end of the cylinder, and the used steam left through a ring of ports at the other end of the cylinder. This allowed the admission end to stay hot, as it was not cooled by the exhaust on its way out, and so improved efficiency. In a double-acting engine the exhaust ports were in the middle of the cylinder.
Almost all uniflow engines were large stationary types, but the system was tried by, among others, the North Eastern Railway in England, as described by Tuplin (see sources). Briefly, the system worked well and obtained a small increase in economy by decreasing fuel consumption, but at the price structure prevailing at that time the extra constructional and maintenance costs were greater than the coal economy. H.W. Dickinson's "A Short History of The Steam Engine" makes it clear that the concept of the uniflow engine reached back to Montgolfier and Jacob Perkins (who patented the idea) and Leonard Jennett Todd (Patent No. 7801): Dickinson then gives Stumpf of Charlottenburg University his due citing a paper by T.B. Perry "Proc. Inst. Mech. Eng.", 1920 (1922?).