Solution Procedure for an Unsteady Calculation

Once a composite grid for the two blade rows was generated, and the interpolations between the H-grids and The O-grids was established, a steady isolated flow solution for each blade row was calculated. The flow conditions at the inlet and the exit of each blade row were taken from an OSO69 turbine design system throughflow run. At the inlet to each blade row, total pressure, total temperature, and flow angles were specified. At the exit, static pressure at the hub and the radial equilibrium equation were used to specify a static pressure radial profile. The steady isolated blade row calculations were run to convergence, and the steady predictions were used as an initial guess for the unsteady calculation.

For the unsteady calculation, the interface between the vane and the rotor allowed direct transfer of unsteady boundary values between the blade rows. For the pitchwise periodic boundaries, boundary data for the number of iterations equal to one rotor passing period was stored and used for the vane. Boundary data for the number of iterations equal to one vane passing period was stored and used for the rotor. The time periodic boundary values for each enable the blade passage solution for each blade row to become periodic in time. Figure 2 shows a plot of the static pressure for reference points on the surface of the vane and the blade at midspan. The vane reference point was near the trailing edge. The blade reference point was near the leading edge.

0,9274 0.9272 0.9270 I 0.9268 0.9266 0.9264 0.9262 0.9260

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