Numerical and Experimental Investigations of Single-Flow and Bypass-Flow Fans

C3 - CFD Validation Studies

During design procedure it is necessary to take into account all characteristic features of fan operation in real-life environment. Defining of bypass ratio influence on local flow parameters and integral performances of fan is time-consuming task. This work highlights a method of computing bypass fan performances on the basis of through-flow 3D viscous flow computation within RANS based on S.K. Godunov's modified implicit scheme. The value of the specified static pressure at the outlets of core and bypass ducts is used as a boundary condition in this work. The strategy in finding solution is similar to the method used in experimental studies of bypass fans when using two independent throttles in each duct.
Numerical predictions of integral performances and steady flow inside the blade-to-blade channel of bypass fans were performed for the reference fan and two counter rotating fan models, investigated in frame of European project VITAL. This paper represents results of computed and experimental data for two counter rotating fan models - CRTF1 and CRTF2, investigated in frame of European project VITAL. Good correspondence of computed and experimental data is observed. The abovementioned solver allows performing calculations of several fan stages in the flow path including the flow split to the core and bypass ducts. In bypass ducts the guide vane OGV, struts and pylons may be taken into consideration. In core ducts the guide vanes IGV, AGV, transition ducts, struts and several stages of booster, for example, or LPC, HPC may also be taken into account.
Numerical and experimental investigation of fan stage S179-1 with the rotor wheel manufactured according to “blisk” technology was performed. Fan stage S179-1 is the scaled model – prototype of bypass fan for advanced turbofan engine. Also numerical and experimental study of bypass fan stage S179-2 was performed, which is the scaled model of the whole bypass fan including four stages booster. For both cases computations showed good correspondence in comparison of numerical and experimental data.