Regenerator seal hub gas passages

A rotary regenerator comprising:

• housing means defining flow paths for air and gas at different pressure levels, an axial flow matrix with a hub including a center opening, said matrix also having open end passages extending across the flow paths, the matrix having said open ended passages pervious to fluid flow through the flow paths, said matrix including inboard and outboard radial surfaces with a pressure differential thereacross, spindle means for rotatably supporting said matrix for rotation with respect to said housing means, an outboard cross arm seal assembly interposed between the housing means and said outboard radial surface and including an outboard cross arm with a platform and wear surface extending between said flow paths for sealing therebetween, said outboard cross arm wear surface having a center hole wear surface region, an inboard cross arm seal assembly including an inboard cross arm having a seal platform and a wear surface engageable with said inboard radial surface to seal between the flow paths at the inboard radial surface of the matrix, means including aligned bores in said outboard and inboard seal assemblies for defining an air circulation path for distribution of cold air from the air path to the outboard seal assembly through the center opening in said matrix and for distributing cold air in surrounding relationship to said spindle means, a center hub wear surface region of said inboard cross arm cooled by cooling air flow through one of said aligned bores, and heater means for reheating said center hub wear surface region to counteract the cooling effect of cooling air flow on the center hub wear surface region of said inboard seal assembly to maintain a uniformly elevated temperature across the full planar extent of the inboard cross arm wear surface to optimize the operating temperature thereof during gas turbine engine operation so as to maintain low friction and wear characteristics between said last mentioned seal wear surface and the matrix, said heater means including undercut grooves in the center hub wear surface regions of the outboard and inboard wear surfaces on the side thereof facing the gas flow path, each of said grooves also facing and being open to said open ended passages in said matrix to pump hot gas from said inboard radial surface of said matrix into the matrix adjacent the central opening therein thence to the outboard radial surface of said matrix in response to said pressure differential thereby to direct a flow of hot gas through the undercut grooves in each of said inboard and outboard cross arms.