A multi-air stream cooling system is provided. The multi-air stream cooling system may comprise an inner vane support, a flow guide, and a fastened inner duct. The inner vane support may partially define a first airflow path. The flow guide may couple to the inner vane support and may partially define a second airflow path. The fastened inner duct may couple to the flow guide and may partially define a third airflow path. The inner vane support may comprise a discharge slot to allow a first airflow into a blade rim cavity. The flow guide may comprise a tangential onboard injector (TOBI) to provide a second airflow through a cover plate. The flow guide may also comprise a bypass passage configured to enable a third airflow from the third airflow path.