On applying large eddy simulation (LES) to engineering interest, one of the keys is to obtain two-order low-dissipation shock-capturing schemes adapted to LES. Therefore, the preconditioning method for all speed flows is adopted. However, the accuracy of preconditioned schemes is not satisfactory because of the poor per-formance of stability of preconditioning techniques especially in viscous flows. The reason of unstability is attributed to the unstability structure in the preconditioned eigenvalue matrix. Based on Roe scheme and two assumptions for low-Mach- Number flows, the new scheme named Low-Speed-Roe scheme is deduced for removing the unstability structure. Numerical experiments show that this scheme has the reasonable computational stability. For general-precision problems, Low-Speed-Roe scheme has similar behavior as the classical preconditioned Roe scheme. For simulations of high-accuracy requirement such as LES, Low-Speed- Roe scheme can obtain better results of complex flows, such as the laminar sepa-ration bubble on the suction surface of the high-loaded turbine blade T106.
