Aerodynamic Performance of Low Speed Axial Flow Compressor Rotors with Sweep and Tip Clearance

Abstract

Blade tip gap, though finite, has great influence on the performance of a turbomachine. Tilting the blade sections to the flow direction (blade sweep) would increase the operating range of an axial compressor by modifying the pressure and velocity fields on the suction surface. The present paper investigates the combined effect of these two factors on various flow characteristics in a low speed axial flow compressor. For the present study, six computational domains were modeled: two rotor sweep configurations (0° and 20°) and three different clearance levels for each rotor. Commercial CFD package ANSYS ® CFX 11.0 is used for the simulations. Results indicated that the effect of tip clearance is more predominant in swept rotor than unswept rotor in terms of change in total pressure rise and efficiency. Traced streamlines indicated that blade sweep guides the suction surface boundary layer fluid towards the trailing edge, preventing it from getting accumulated near the tip. Studies near the tip region showed the pattern of velocity streamlines through the tip gap. Tip clearance vortices are found and their trajectory and effect on the flow are studied. Total pressure rise contours at the rotor exit showed that radial migration of low energy boundary layer fluid towards the tip sections is well prevented with sweep.

Experimental and Numerical Investigation of a Compressor Cascade at Highly Negative Incidence

“…Finally, validation-calibration of CFD codes for predicting the extremely challenging areas of separated flows can be also carried out (Pachidis et al, 2006). The increased computational power available nowadays throughout the research community has increased the application of high-fidelity numerical approaches on every kind of flow prediction, starting from pure aerodynamic phenomena occurring at inlets or compressors and extending them in combustion or turbine cooling research, employing multidisciplinary tools of chemical or heat transfer nature (Chaluvadi et al, 2003;Ramakrishna et al, 2009;Ummiti et al, 2009). In case of far off-design turbomachinery performance studies such as the above-described ones, the availability of experimental datasets is the only aspect that prevents the numerical tools from being further validated and at a second stage further improved.…”

On loading corrections and loss distributions in low-speed forward swept axial compressor rotors

“…The Fig. 4 Flow domain with the given boundary conditions results obtained with these two turbulence models were compared with the available experimental results (given in reference [17]). Grid independency study was also conducted and the mesh size was optimized to about 700 000 mesh elements for the rotor and 450 000 elements for the stator.…”

“…Grid independency study was also conducted and the mesh size was optimized to about 700 000 mesh elements for the rotor and 450 000 elements for the stator. Details of the mesh, grid independence study, wall function treatment and y+ pertaining to the present study can be found in Ramakrishna and Govardhan [17]. Details of the flow domain with the given boundary conditions are shown in Fig.…”

Inception of Casing Wall Flow Instabilities and Downstream Flow Evolution in Subsonic Axial Compressor Rotors At High Rotor Stagger Angles

“…Details of the computational methodology adopted in the present work, numerical validation and so forth, have been presented in Ref. [17][18][19] in detail; and will not be repeated here. High quality hexahedral grids have been employed in the computations.…”