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: Turbulence & Mach number. The organization has 404 authors who have published 420 publications receiving 4183 citations. The organization is also known as: DRDL.

Numerical Simulation of Missile Jet Deflector

Abstract: A numerical simulation was carried out to estimate the heat flux on a jet deflector caused due to impingement of the rocket exhaust of a canisterized missile. Three-dimensional Navier–Stokes equati...

Damping numerical oscillations in hybrid solvers through detection of Gibbs phenomenon

Abstract: Summary A Gibbs phenomenon detector that is useful in damping numerical oscillations in hybrid solvers for compressible turbulence is proposed and tested. It is designed to function in regions away from discontinuities where commonly used discontinuity sensors are ineffective. Using this Gibbs phenomenon detector in addition to a discontinuity sensor for combining central and shock capturing schemes provides an integrated way of dealing with numerical oscillations generated by shock waves and contact lines that are normal to the flow. When complete suppression of numerical oscillations is not possible, they are sufficiently localized. Canonical tests and large eddy simulations show that inclusion of the proposed detector does not cause additional damping of “well resolved” physical oscillations. This article is protected by copyright. All rights reserved.

Einfluß der Geometrie auf die Wärmeleitung in Kühlkanälen einer Flüssigkeits-Rakete

Abstract: Die Arbeit zeigt einige typische Ergebnisse fur zweidimensionale, stationare Warmeleitung in Kuhlkanalen mit der Randbedingung dritter Art, wie sie ublicherweise bei gekuhlten Flussigkeitsraketen auftreten. Es werden kreisformige, rechtwinkelige, trapezformige und gleichschenkelig-dreieckige Querschnitte mit gerundeten Ecken betrachtet. Die Losungsmethode fust auf dem Rand-Kollokationsverfahren der linearen Anpassung mit Hilfe des Prinzips der kleinsten Fehlerquadrate unter Verwendung von Householder-Reflexionen.

Development of ANFIS Model for Flow Forming of Solution Annealed H30 Aluminium Tubes

Abstract: Modeling of the cold flow forming process for manufacturing of tube shaped solution annealed H30 Aluminum alloy has been considered in this present study. Three inputs (feed-speed ratio, roller in-feed and roller axial stagger) and three outputs viz. spring back, ovality and internal diameter have been considered for the present study.. Adaptive network-based fuzzy inference system (ANFIS) in Matlab platform has used for modeling purposes and its performance is compared with regression model. ANFIS has completely outperformed the regression models. Percentage accuracy in predicting all the three responses are found to be very high with ANFIS models. Prediction of ovality against the test data using regression analysis is found to be extremely erroneous. It indicates that additional process parameters are involved in predicting ovality which are not captured during the experimentation.

Effects of various tool pin profiles on mechanical and metallurgical properties of friction stir welded joints of cryorolled AA2219 aluminium alloy

Abstract: Friction stir welding (FSW) process was conducted on cryorolled (CR) AA2219 plate using different tool pin profiles such as cylindrical pin, threaded cylindrical pin, square pin and hexagonal pin profiles. The FSW was carried out with pairs of 6 mm thick CR aluminium plates with different tool pin profiles. The different tool pin profile weld portions' behaviors like mechanical (tensile strength, impact and hardness) and metallurgical characteristics were analyzed. The results of the mechanical analysis revealed that the joint made by the hexagonal pin tool had good strength compared to other pin profiles. This was due to the pulsating action and material flow of the tool resulting in dynamic recrystallization in the weld zone. This was confirmed by the ultra fine grain structure formation in Weld Nugget (WN) of hexagonal pin tool joint with a higher percentage of precipitate dissolution. The fractograph of the hexagonal tool pin weld portion confirmed the finer dimple structure morphology without having any interior defect compared to other tool pin profiles. The lowest weld joint strength was obtained from cylindrical pin profile weld joint due to insufficient material flow during welding. The Transmission Electron Microscope and EDX analysis showed the dissolution of the metastable θ ″, θ ′ (Al2 Cu) partial precipitates in the WN and proved the influence of metastable precipitates on enhancement of mechanical behavior of weld. The XRD results also confirmed the Al2 Cu precipitation dissolution in the weld zone.