Engineering topics

Martin, Thomas J.

Publications and source records attributed to Martin, Thomas J..

5 records

DOE OSTI2022

Airfoil with CMC liner and multi-piece monolithic ceramic shell

An airfoil includes an airfoil section that has an airfoil wall that surrounds a cavity. The airfoil wall includes an exterior monolithic ceramic shell and an interior CMC liner that has CMC plies. An outermost ply of the CMC plies forms tabs that are raised from an underlying ply so as to define a slot. The exterior monolithic ceramic shell includes an underlapping shell piece and an overlapping shell piece. The underlapping shell piece has a portion disposed in the slot and bonded with the tabs. The overlapping shell piece extends over the tabs and is bonded to the tabs. There are channels bounded by adjacent ones of the tabs, the underlapping shell piece, and the overlapping shell piece. Channel orifices through the CMC liner connect the cavity and the channels.

Martin, Thomas J.↗

DOE OSTI2022

Ceramic airfoil trailing end configuration

An airfoil includes an airfoil body that has a trailing edge region. The trailing edge region includes first and second monolithic ceramic exterior walls, a flow discharge passage between the first and second monolithic ceramic exterior walls, a ceramic matrix composite (CMC) liner at least a portion of which is disposed in the flow discharge passage between the first and second monolithic ceramic exterior walls, and an array of pedestals disposed in the flow discharge passage. Each of the flow guides bridges the CMC liner and at least one of the first and second monolithic ceramic exterior walls.

Kennedy, Matthew B.↗

DOE OSTI2021

Airfoil having internally cooled wall with liner and shell

An airfoil includes an airfoil section that has an airfoil wall that surrounds a cavity. The airfoil wall includes a first wall section comprised of a monolithic ceramic shell, a second wall section comprised of a CMC liner that is bonded along an interface to an interior side of the monolithic ceramic shell, and a ceramic barrier coating that is bonded to an exterior side of the monolithic ceramic shell. The airfoil wall includes at least one of: inter-section cooling channels that extend along the interface and are bounded by the monolithic ceramic shell and the CMC liner, or intra-section cooling channels that extend within the CMC liner.

Croteau, Paul F.↗

NASA NTRS1993

A direct approach to finding unknown boundary conditions in steady heat conduction

The capability of the boundary element method (BEM) in determining thermal boundary conditions on surfaces of a conducting solid where such quantities are unknown was demonstrated. The method uses a non-iterative direct approach in solving what is usually called the inverse heat conduction problem (IHCP). Given any over-specified thermal boundary conditions such as a combination of temperature and heat flux on a surface where such data is readily available, the algorithm computes the temperature field within the object and any unknown thermal boundary conditions on surfaces where thermal boundary values are unavailable. A two-dimensional, steady-state BEM program was developed and was tested on several simple geometries where the analytic solution was known. Results obtained with the BEM were in excellent agreement with the analytic values. The algorithm is highly flexible in treating complex geometries, mixed thermal boundary conditions, and temperature-dependent material properties and is presently being extended to three-dimensional and unsteady heat conduction problems. The accuracy and reliability of this technique was very good but tended to deteriorate when the known surface conditions were only slightly over-specified and far from the inaccessible surface.

Martin, Thomas J.↗

NASA NTRS1993

Unsteady three-dimensional thermal field prediction in turbine blades using nonlinear BEM

A time-and-space accurate and computationally efficient fully three dimensional unsteady temperature field analysis computer code has been developed for truly arbitrary configurations. It uses boundary element method (BEM) formulation based on an unsteady Green's function approach, multi-point Gaussian quadrature spatial integration on each panel, and a highly clustered time-step integration. The code accepts either temperatures or heat fluxes as boundary conditions that can vary in time on a point-by-point basis. Comparisons of the BEM numerical results and known analytical unsteady results for simple shapes demonstrate very high accuracy and reliability of the algorithm. An example of computed three dimensional temperature and heat flux fields in a realistically shaped internally cooled turbine blade is also discussed.

Martin, Thomas J.↗