National Aerospace Laboratories

About: National Aerospace Laboratories is a facility organization based out in Bengaluru, India. It is known for research contribution in the topics: Coating & Corrosion. The organization has 1838 authors who have published 2349 publications receiving 36888 citations.

Experimental Studies on a Rudimentary Four Wheel Landing Gear

Abstract: Experiments were carried out on a rudimentary four-wheel landing-gear arrangement to understand the flow physics of this configuration. Measurements carried out included oil-flow visualization, steady surface pressures and two-dimensional particle image velocimetry measurements in the near wake at a Reynolds number based on wheel diameter of 1 � 106. The surface visualization demonstrated the significantly asymmetric behavior of the flow on both the front and back wheel. The surface-pressure data show that separation is earlier on the wing side as opposed to the ground side for both wheels, caused by the presence of the vertical strut. The data show that the truck and strut are dominant contributors to the total drag. The off-body measurements in the near wake document the confluent wakes from the wheel and the horizontal strut leading to a three-dimensional unsteady wake. The data presented here provide a comprehensive picture, both quantitatively and qualitatively, of the flow over a rudimentary landing gear and are useful for validation of computational fluid dynamics efforts in addition to understanding the flow physics of such configurations.

Electrochemical studies of stainless steel implanted with nitrogen and oxygen by plasma immersion ion implantation

Abstract: Plasma Immersion Ion Implantation (PIII) of stainless steel with nitrogen at temperatures lower than 400 °C has been reported to increase the hardness of the material by several times. However, expectations that the corrosion resistance will remain unaffected after implantation were not found to be so. In the present study the influence of post-oxygen implantation on the corrosion resistance of nitrogen implanted stainless steel is presented. Stainless steel samples were subjected to oxygen, nitrogen and post-oxygen ion implantation at different temperatures. GIXRD and microRaman studies of the implanted samples showed that oxygen implantation leads to the formation of an oxide layer consisting of corundum and spinel structures. The corrosion properties of the implanted samples were studied by potentiodynamic polarization and electrochemical impedance techniques in 3.5% NaCl solution. After nitrogen implantation the corrosion current increased and the corrosion potential shifted to the less noble side to − 0.486 V as compared to − 0.284 V for the substrate. Oxygen implantation at 400 °C shifted the corrosion potential to the nobler side to − 0.2 V with decrease of corrosion current. For post-oxygen ion implantation at temperatures lower than 400 °C, the corrosion current was higher than the substrate and the corrosion potential was also on the less noble side. However, post-oxygen ion implantation at 400 °C after nitrogen ion implantation resulted in improved corrosion resistance as the corrosion potential shifted to nobler side and the corrosion current was lower than that of substrate.

Moisture Diffusion Behaviour of T300-914C Laminates:

Abstract: This paper presents the moisture diffusion characteristics of autoclave moulded T300-914C unidirectional composite specimens hygrothermally conditioned at 85% RH and 70'C till saturation to 1.5% moisture content. In all, pin bearing strength test specimens of three different layup sequences viz. [45/03/ A 45/03/90/0],, [0/ 4 45/9012s and [45/02/45/03/45/0], were studied. All the test specimens exhibited Fickian Diffusion behaviour. It was further found that the Diffusion coefficient (D,) value of the composites increased with increase in the cut edge surface area and the values obtained compared well with those reported in literature. The difference in D, values obtained for different layup sequences was attributed to tortuousity caused by fibre orientations.