Abstract
A local loss model and an integral loss model are proposed to study the irreversible flow loss mechanism in a linear compressor cascade. The detached eddy simulation model based on the Menter shear stress transport turbulence model (SSTDES) was used to perform the high-fidelity simulations. The flow losses in the cascade with an incidence angle of 2°, 4° and 7° were analyzed. The contours of local loss coefficient can be explained well by the three-dimensional flow structures. The trend of flow loss varying with incidence angle predicted by integral loss is the same as that calculated by total pressure loss coefficient. The integral loss model was used to evaluate the irreversible loss generated in different regions and its varying trend with the flow condition. It as found that the boundary layer shear losses generated near the endwall, the pressure surface and the suction surface are almost identical for the three incidence angles. The secondary flow loss in the wake-flow and blade-passage regions changes dramatically with the flow condition due to the occurrence of corner stall. For this cascade, the secondary flow loss accounts for 26.1%, 48.3% and 64.3% of the total loss for the flow when the incidence angles are 2°, 4° and 7°, respectively. Lastly, the underlying reason for the variation of the secondary flow loss with the incidence angle is explained using the Lc iso-surface method.
Highlights
The total pressure loss coefficient and entropy loss coefficient have played an important role in the study of flow losses in turbomachines
A local model and an integral loss model based on the SSTDES computational model were evaluated theoretically
The local and integral loss distribution varying with flow incidence angles were
Summary
The total pressure loss coefficient and entropy loss coefficient have played an important role in the study of flow losses in turbomachines. Based on the adiabatic hypothesis, these parameters have been successfully used to evaluate the global loss generated in the blade passage and to locate the low-energy fluid accumulation zones [1,2]. These two quantities do not allow quantification of the ratio of different loss sources in the flow field or analysis of the distribution of the local flow loss. The first local loss model, proposed by Moore [4], is based on the Reynolds-averaged Navier–Stokes (RANS) method It assumes that the turbulent fluctuations of the heat flux and viscous dissipation in the positive definite entropy equation can be modeled by incorporating turbulent conductivity and turbulent viscosity to the molecular conductivity and viscosity, respectively.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have