Parasitic secondary flows (seals leakage) in centrifugal compressors and gas and steam turbines represent a substantial loss in efficiency and power delivery with an increase in specific fuel consumption. Labyrinth seals (LBS) are the most prevalent and inexpensive means of reducing secondary leakage, albeit wearing out with operation and thereby penalizing performance and affecting rotordynamic stability. Brush seals (BS), although costlier, are common in specialized applications (aircraft engines). BS may increase plant efficiency by up to one-sixth of a point and with as little as 10% of the leakage in a similar size labyrinth seal. The Hybrid Brush Seal (HBS) is a novel design that adds to the bristle brush matrix a number of cantilever pads that rest on the rotor surface. Upon shaft rotation, the pads lift due to the generation of a hydrodynamic gas film while the brushes effectively seal an upstream pressure. Hence the HBS has no wear and no local thermal distortion effects. Most seal leakage measurements to date were obtained at room temperature. Presently, a test rig for measurement of leakage in short length seals operating at high temperature (300°C) and with shaft surface speed to 26 m/s is available at TAMU. The seminar presents a description of the test facility and reports the recorded flow rate (leakage) in three seals of similar size and axial length: a three tooth LBS, a conventional BS, and a HBS. The objectives are to quantify the leakage performance for each seal type, to compare results among the tested seals, and to recommend the most reliable sealing technology for ready implementation in power gas turbines for the oil and gas industry. The measurements demonstrate the HBS leaks ~31% less than the BS and is significantly better (~68%) than the LBS. As temperature increases, the LBS leakage decreases because its clearance changes due to the thermal growth of the components. The HBS, on the other hand, shows leakage that is nearly insensitive to air inlet temperature. Recent (surprisingly low) leakage measurements for a novel seal named HALOTM are also disclosed. Siemens Power Generation, Inc. and Advanced Technologies Group (ATG) sponsored the research from 2007-2009. The project began in 2006 with a seed grant from Siemens-Westinghouse Emerging Technology Embryonic University Program. The research products—reliable test data and predictive tools, experimentally benchmarked—enable the application of state-of-the-art sealing technology that increases system efficiency by reducing leakage and extends maintenance intervals by eliminating wear of components. | 
