Defence Research and Development Laboratory

About: Defence Research and Development Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Mach number & Turbulence. The organization has 404 authors who have published 420 publications receiving 4183 citations. The organization is also known as: DRDL.

Enhancement of strain tolerance of functionally graded LaTi2Al9O19 thermal barrier coating through ultra-short pulse based laser texturing

Abstract: Functionally Graded Thermal barrier coating (FG-TBC) based on LaTi2Al9O19 was prepared via air plasma spray and textured using pico-second Nd:YAG laser (wavelength 532 nm, 3 W) over the coating surface to resist the delamination or failure stresses caused by thermal mismatch when exposed to high temperature. Different laser scan speeds, depth and width were set on each sample and the surface structure was investigated by thermal shock test. The microstructure and surface morphology were analyzed by SEM and 3D Profilometer. In the case of the laser-textured TBC, the re-melted coating layer was completely absent. It was found that the laser textured grooves with 375 μm spacing enhances the strain tolerance of TBC and provides excellent thermal durability and lifetime of more than 186 cycles. When top layer experience expansion and contraction under high temperature exposure, the grooves in the top layer of FG-TBC provide additional stress/strain relief gap and prevents the coating from failure.

Numerical investigation of transverse sonic injection in a non-reacting supersonic combustor:

Abstract: Efficient combustion and heat release in scramjet flows depend on effective mixing of the fuel in supersonic streams. Usually, transverse sonic injection in-stages are employed as one of the suitable means for efficient supersonic combustor design. Numerical simulations are carried out to study the mixing characteristics of staged sonic air injections in supersonic stream (M = 2.07) behind a backward-facing step in scramjet combustor by solving three-dimensional Navier-Stokes equations along with K-e turbulence model with a commercial CFD software CFX-TASCFlow. Computed results of the jet penetration and spreading show very good agreement with the experimental values and the results of other computations. A good overall match has been obtained between the experimental values and the computation for various flow profiles at various axial locations in the combustor. However, the values differ in the near-field region at the injection plane. The assumed uniformity of the flow-field properties at the ...