. The Street railway journal . thesemoving and stationary elements the velocity acquired in thenozzle is fractionally abstracted, and largely given up to themoving element. Thus the steam is first thrown against thefirst set of vanes of the moving element, and then reboundsalternately from moving to stationary vanes until it is broughtnearly to rest. By this means a high steam velocity is madeto efficiently impart motion to a comparatively slowly-moving occasion loss by re-evaporation, is drained out of each stageinto that which succeeds it. The governing is effected by successive closing of n
. The Street railway journal . thesemoving and stationary elements the velocity acquired in thenozzle is fractionally abstracted, and largely given up to themoving element. Thus the steam is first thrown against thefirst set of vanes of the moving element, and then reboundsalternately from moving to stationary vanes until it is broughtnearly to rest. By this means a high steam velocity is madeto efficiently impart motion to a comparatively slowly-moving occasion loss by re-evaporation, is drained out of each stageinto that which succeeds it. The governing is effected by successive closing of nozzlesand consequent narrowing of the active steam belt. The cutshows part of the nozzle open and part closed; the arrowsshowing space filled by live steam. In the process of governing,the nozzles of the later stages may or may not be opened andclosed so as to maintain an adjustment proportional to that ofthe first stage, which is always the primary source of improvement of light load economy may be effected by. COMPARISON OF 200-kw, 9000-R. P. M. DE LAVAL , .mKW, 1800-R. P. M. CURTIS TURBINE AND 375-KVV, 3G0O-R. P. M. PARSONS TURBINE clement. The nozzle is generally made up of many sectionsadjacent to each other, so that the steam passes to the wheels ina broad belt when all nozzle sections are in flow. This process of expansion in nozzle and subsequent abstrac-tion of velocity by successive impacts with wheel vanes is gen-erally repeated two or more times, the devices for eachrepetition being generally designated as a stage. There may bevarious numbers of stages and various numbers of lines ofmoving vanes in each stage. The number of stages and thenumber of lines of vanes in a stage are governed by the degreeof expansion, the peripheral velocity which is desirable or prac- maintaining a relative adjustment of all nozzles; but in manycases the practical difference in economy is not great, and auto-matic adjustment of nozzle opening in later stages is dis
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
