Research On The Mechanism Of Sealing And Ingestion In Gas Turbine Rotor-stator Rim

Under the trend of going for higher efficiency, Gas Turbine componentsface more stringent working condition and become obvious reciprocal influence.As for the secondary air system in the first stage nozzle and blade, which arecommitted to guarantee blade cooling air, it will be badly damaged if the hot gasintrudes through rotor stator rim. In the light of this, the flow and heat transfermechanism of sealing and ingestion in high temperature turbines was studied inthis paper. The research was carried out in three aspects. Firstly the flow andheat transfer problems in typical cavity was investgated. The seal and ingestionmechanism in one stage turbine was studied based on above-mentionedfundamental work. The interaction and optimization analysis between sealingflow and turbine cooling flow was done then. From fundamental rotor cavitystrcutures to turbine stage, the sealing and ingestion problems were studied stepby step.The "secondary air system unit test rig" was designed and built up.Different seal strcutures and Pre Swirl systems were tested in the absence ofannulus flow in this rig by TLC measurement method. Meanwhile, CFDmodelling was conducted to compare with experimental data. These resultsshow that the pumping effect caused by rotating disc is the main cause ofingestion. The heat transfer was enhanced with the impingement flow inducedby Pre Swirl nozzle.One stage turbine rim seal model was used to study the ingestion problemsin the presence of annulus flow. It aimed to uncover the annulus flow ingestionmechanism, the mixing process of sealing and ingestion flow, the characteristicof different seal structures. A new effectiveness prediction model was developedbased on J. M. Owen’s "orifice model" and was validated with experimental data.The new model can be used to calculate sealing effectiveness simply frompressure measurement, and the results were consisted with those fromconcentration measurements. The interaction and optimization between sealing flow and turbine coolingflow were analysised, focusing on endwall flank holes and preswirl nozzle. Anew arrangement of endwall flank holes and Pre Swirl nozzle were proposed andvalidated to be more conducive to seal effectiveness.Much work have been done around the flow and heat transfer mechanism ofsealing and ingestion in Gas Turbine by experimental tests, numericalsimulations and theory analysis. The principle of designing a high efficiencyseal structure was concluded and a new sealing effectiveness prediction modelby using pressure measurements was developed and validated. It was hoped thatthese conclusions will be helpful and useful in Gas Turbine industrial design.