A steady flow of an incompressible Newtonian fluid in pipelines with anaxisymmetric sudden contraction was studied in the range of 102"'104 of Reynoldsnumber by experiments on pressure drops and a theoretical analysis using thefinite difference methods. The main results obtained are as follows:(1) The sudden contraction loss decreases with increase in Reynolds numberand approaches a certain value at high Reynolds number. Besides， thesudden contraction loss has a kind of transition phenomenon at Reynoldsnumber equal to (2～4) x 103.(2) The numerical prediction of the pressure distribution at pipe wall in thedirection of flow does not agree with experimental results in higher Reynoldsnumber than about 103. This disagreement increases with increase inReynolds number.(3) The recovery distance of pressure due to sudden contraction lengthenswith increase in Reynolds number and the pressure gradient after recoverybecomes more gent1e.(4) 1n Reynolds number over about 103，the separation bubble is formed inthe downstream side of sudden contraction and it increases with increasein Reynolds number in the range of (103～104)of Reynolds number.
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