Numerical Simulation Of Using Blade Tip Winglet In Plane Compressor Cascade

Tip clearance flow has profound effects on the performance and stability of the compressor.To improve the performance of compressor,it is important for the researchers to understand how to control the tip clearance flow and increase efficiency. Recently,tip winglet controlling gap flow technique has also been concerned in the field of turbomachinery.Investigating its action effect and its mechanism can lay the foundation for enhancing the reliability,validity of tip winglet technique application as well as create condition for developing new measures to control the gap flow.In this paper,a detailed numerical simulation has been carried out for the subsonic plane compressor cascade composed of NACA65 straight blades equipped with winglet on the blade tip suction-side,winglet on the blade tip pressure-side and combined winglet(with winglet on the suction-side and pressure-side) respectively at zero incidence.For the tip winglet itself,there are several different profile parameters,such as width,length and spanwise location.By means of the analysis,the optimum width,length spanwise location of the tip winglet are obtained under different tip clearances.Compared with the conventional cascade,the tip leakage vortex core in the cascade equipped with suction-side tip winglet moves to pressure side of the adjacent blade.The changing of the location of leakage vortex has two aspect effects,on the one hand,it can reduce the leakage scrolling more low-energy fluid of the suction side/endwall area,on the other hand,it can stop the development of the tip passage vortex earlier.At the same time,the installation of the suction-side winglet increasing the movement friction of the leakage vortex,which to some extent reduces the intensity of the leakage vortex.The numerical results show that there is an optimum width and length suction-side winglet case corresponding to a gap flow field.The pressure-side winglet makes the track of the tip leakage voetex offset to the suction side,resulting the leakage vortex scrolling more low-energy fluid of the suction side/endwall area,therefore increasing the total loss.In all tip clearance conditions,all width and length cases of pressure-side tip winglet have not improved the top gas flow condition of the cascade clearly,while the wider tip winglet deteriorates the aerodynamic performance of the small tip clearance cascade.In combination winglet cascades,the prseeure-side and suction-side winlet effect the tip flow at the same time,mainly be reflected on the changes of the leakage vortex core's location and radial size and circular size.The pressure-side winglets play a dominant role in the wider pressure-side winglet combination,making the leakage vortex core migrated to the suction side,thus the loss increases a little.In the wider suction-side winglet combination and the same width of both sides winglet combination,the role of the suction-side winglet much more dominant,the leakage vortex core develops to the direction away from the suction side,and the total cascade loss lower than the conventional cascade.