An Experimental Study On The Aerodynamic Performances Of Steam Turbine Remodeled Blades

Experimental had been done to study aerodynamic performance of a steam turbine rotor cascades of prototypical and modified,to understand flow field structure of two sets cascades,to explore the growth mechanism of loss in the different incidences,and to verify the correctness of the design concept is based in blade remodeled.Using fan-shaped test model of blade cascades in experimental due to the restricted experimental conditions.In the wind tunnel test rig of subsonic annular cascades,a static testing of steam turbine rotor cascades had been done.The effect of centrifugal force on the steam cannot be ignored as the annular rotor cascades and high-speed rotating,so the results of experimental do not fully reflect the actual flow.However,by comparing the test results under the same conditions,it can evaluate the aerodynamic performance of rotor cascades in a certain extent.In this paper,the distributions of aerodynamic parameters which along the pitch and blade height,also the surface static pressure distributions along the blade profile of prototypical and modified rotor cascades had been measured in the five incidences,which including 0 °,± 5 o,± 10 o by using five-hole measuring probe and static holes which set on the surface of blade.Test results were represented in the following: the blade surface static pressure distributions along the profile under different incidences;the isoline cloud of exit Mach number,static pressure coefficient and loss coefficient;the mean parameters distributions of pitch along the blade height;the total parameters in different incidences.It can be judged the success of the retrofit design through the analysis of test results.Although prototypical cascades with aft-loaded profile,test results show that the loss is large,especially the secondary flow loss of root due to the distributions of blade cross section aerodynamic load along the blade height is not perfect.The remodeled cascades also with aft-loaded profile optimizes the distributions of aerodynamic load along the blade height.Aiming at the loss is higher of prototype root,remodeled cascades reduces blade aerodynamic load of blade root and removes the location of minimum pressure of suction side to the about 90% axial chord length.In this way,the horizontal pressure gradient of front and middle flow massage on hub wall is significantly reduced and adverse pressure gradient length of suction side exit is shortened so to reduce the secondary flow loss and profile loss.Compared with the prototypical cascades,the flow loss on root and middle of modified cascades is obviously decreased,but there is a little of change on the top.In addition,the remodeled cascades has optimal aerodynamic performance under the small negative incidences and very well adaptability to incidences.The higher incidences,the larger loss reduced of remodeled cascades.