| Experiments have been done to study the profile of first stage stator blade which with internal cooling structure and the aerodynamic characteristics of the static cascade of a heavy duty gas turbine,to analyze the physical mechanism of the increase of the flow loss under different incidence angle,then to provide technical support for the modification Design of the gas turbine.In this paper,the blade profile of different blade high and the stator cascade are taken as experimental models.And the tunnel test has been taken in subsonic low-speed wind tunnel experiment table.For the blade profile aerodynamic characteristics,the blade profile of root/ middle / top of blade height have been be chosen as the generatrix of the experimental cascade,and then along the exhibition to stretch for forming a straight blade with constant section.Three sets of inline cascade have been constructed with the corresponding leaf high pitch and blade installation angle.In the cascade experiment,the width of hub of the actual cascade root is less than 4-5 times the diameter of the probe head has been taken into account,so the actual blade has been amplified according to the geometric similarity.In the end,sectorial turbine cascade with seven blades has been selected as test cascade.Five-hole beam probe are used in flow field measurement of cascade upstream and cascade downstream.Blade aerodynamic characteristics experiments have been conducted five indifferent incidence angle(0°?±5° and ±10°).Only in the central lobe show along the direction of the pitch measurement.Static holes are decorated in pressure side and suction side of blade to measure pressure coefficient distribution along the blade.The static pressure measuring hole is orthogonal to the profile of the position.For fan-shaped cascades,the distribution of air flow parameters along the blade height and pitch is measured at 0 ° and ± 10 ° incidence angle.Static pressure measurement holes have been set up in blade profile of three blade height to measure the static pressure coefficient distribution along the different blade height.The measured the results of blade profile of the heavy gas turbine first stage stator blade and the cascade flow field show that the total pressure loss of the blade section of the root,middle and parietal lobes in different incidence angles varies between 0.025 and 0.036,and the variation amplitude is 0.11.Airflow deflection is slightly higher than 1 °.So compared with geometric outlet flow angle of corresponding blade height,the change of outlet flow angle can be ignored.Compared with conventional turbine blade profile without internal cooling structure but with the same turning angle,the total pressure loss is slightly higher and the deviation angle is similar.The results of the cascade experiments show that the aerodynamic load is almost the same and the blade profile is preloaded because the uniformity of the flow along the leaf is taken into account in the design of the leaf type.In the same incidence angle,the average total pressure loss coefficient fluctuation is very small along the blade height except for sides of the end wall area.In the incidence angle of 0 ° and ± 10 °,the average flow loss coefficient of mass flow is 9.98%,12.1% and 11.3% respectively.Relative to 0 °incidence angle,flow loss caused by± 10 ° incidence angle increased by 2.1% and 1.3%.The technology of controlling second flow with forward sweep blade and the converged end wall meridian plane profile is used to reduce the flow loss in endwall and improve the adaptability of cascade incidence angle.Finally,the topological structure of the shear wall of the experimental cascade is given according to the flow spectrum of the blade surface and the end wall,and the concentrated vortex structure of the cascade is deduced.It is pointed out that the gas turbine cascade whether the topological or vortex structure is more complex than the conventional cascade without internal cooling,the blade design needs to be a research focus in the field of gas turbine. |
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