| The transition of boundary layer from laminar to turbulent plays an important role in turbine machine. Solving Parabolized Stability Equations(PSE), a numerical method is presented in this dissertation, which is based on wind tunnel experiment date to analyze, predict and estimate the boundary flow stability.A stability PSE equation is developed in the dissertation. In order to generalize the equation for geometries with curved blade surfaces, an orthogonal curvilinear coordinate system is introduced. The numerical discretization and the finite diffence scheme are both proposed. Based on experiment date of blade surface pressure distribution, the mean parameters of the boundary flow can be solved with the Falkner- skan- Cooke equation in curvilinear coorinate system. The results are then used to be the initial parameters for the stability equations. Numercal solution codes are developed, in which the global and local methods are both used. The eN method is used for the criterion of the boundary flow stability and transition prediction in the blade cascade boundary flow stability problem. All of these methods can be used in stability analysis of both tubine and compressor blades.The off-design performances of stator and rotor blades in the 8th stage of 600Mw supercritical steam turbine and their boundary flow stabilities are all analyzed in this dissertation. Two sets of blades are both aft-loaded profile. It is shown in the result that the flow at the mid span of blade is relatively steady, while the flow near the endwall is relatively unstable.To analyze the influence of incoming flow on the boundary layer stability, computation is performed in the governing-stage guide vane of 600Mw super-critical steam. It is shown that when the incidence is changed, the boundary flow near the endwall is remarkably affected, but the flow at the mid span is not changed conspicuously. These results indicate that using aft-loaded cascade, the lowest pressure point on blade suction surface is moved to be about 60% axial chord, the transition is put off, the stability of cascade surface is enhanced and the incidence sensitivity is weakend effectively. In order to investigate the influence of external flow parameter on the boundary flow stability, the blade surface boundary flow stability of the governing-stage guide vane in 600Mw supercritical steam turbine is computated. It is shown in the result that the disturbance of external flow patameter clearly affects the stability of the blade surface flow. When inlet flow velocities are increased, the Reynold number is increased also. The increase of the Reynold number leads to the decrease of the flow stability. If increasing the inlet Mach number and keeping the Reynold number constant, the stability should be increased with the Mach number. Furthermore, the external disturbing frequency is important influencing factors of stability. When the disturbing frequency is changed, there exists a local maximal disturbing magnification. Near this point the disturbance is easily magnified, so the flow transition is easy to occur.The influence of the second flow on the boundary flow stability in general designed blade is also discussed in this dissertation. From the computation of the boundary flow stability in the diffused meridional flow passage, it is found that the difussed meridional passage thickens the boundary flow in the blade tip and discreases the flow stability there. If the forwardly swept blade is used, the negative effect on stability in blade tip is able to be descreased.Finally, the effect of boundary flow stability in a diffuser cascade with bowed blade is discussed. The boundary flow stabilities on the suction and pressure surfaces in both the straight and bowed blades are solved. It is shown that the boundary flow stability near the endwall of the bowed blade suction surface is enhanced, but that at the mid span is reduced. So the performence of cascade can be enhanced by selecting appropriate bowed angles.
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