Caratterizzazione del campo di moto a valle di schiere di turbina a disegno 3D in una galleria del vento anulare di nuova concezione

Three-dimensional blade design is nowadays widely di used, for both high and low pressure stages, to improve performance of steam and gas turbines. The reason who justify this di usion is linked to their in uece on secondary ow eld, and consequently, they permit to control the discharge angle. This work point out the uidodynamics e ects generated by a three-dimensional blade pro le, designed with leaning and bowing techiniques, in an anular cascade. The leaned blades are obtained by tangentially shifting the blade axis, but this feature implies that the blade axis reamin straight. The axis of the bowed blade is de ned as an arc of circle, centred at mid span section. The aim of this work, performed at the laboratorio di uidodinamica delle macchine of Politecnico di Milano, is to probe udodynamics e ects dowstream a three-dimensional anular cascade with a particular attention to ow discharge angle and vorticity intensity created by the bowed pro le. A prismatic blade was tested too, and assumed as a reference for the downstream ow eld discussion. Numerical data, performed at the Politecnico di Milano by [8] on both blade pro- le, was considered too, in order to get further informations on ow eld and for check the numerical model. Experimental tests were performed using a pneumatic ve hole probe. The rst part of this work was focused on the determination of the incaming ow eld to the testing cascade. In the second part of this word, were performed the downstream ow eld analysis, rstly on prismatic cascade and then on the three-dimensional one. Results were compared emploing bidimensional graphics and mean values. Other experimentals result were provided by older test performed on a straight cascade arrangement; this data have been usend as a starting point for the interpretation of the uidodynamics e ects provided by the bowed blade. The results con rmed that the bowed technique deeply in uenced the pressure loss intensity and distribution, the vorticity and the discharge angle, to sustain what already observed with other test performed on straight cascade.