Abstract
The complicated fluid flow at the tip of a typical bristle within a brush seal is simulated. A numerical model is developed to compute the three-dimensional details in the bristle tip region. Experimental and numerical leakage data are correlated to obtain an estimation of the flow through the overall brush seal. A parametric study is conducted by examining the flow through different seal geometries and associated bristle configurations. Comparisons are made between seals of different bristle angle, bristle diameter, bristle free length, seal backplate diameter, and lift-off gap. Numerical flow visualization illustrates the three-dimensional flow field, showing the circumferential, axial, and radial components of velocity near the bristle surface. Major flow characteristics (separation and recirculation) occur within the inter-bristle spacing and in the lift-off gap. The result of the investigation reveals that the geometry of the brush seal and associated bristle configurations can greatly influence the leakage. The moment due to the forces acting at the bristle tip can increase the lift-off gap which may increase leakage through the seal. For all seals considered, the radial force component is significantly greater than the tangential force component because the large stagnation pressure force predominately in the radial direction prevails over the smaller shearing force observed in the circumferential direction.
Phung, Anh Ngoc (1995). Numerical simulation of the flow field and the lifting forces in the bristle tip region of a brush seal. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -P48.