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.

Effects of Angle of Attack and Bluntness on Heating Rate Distribution of Blunt Models at Hypersonic Speeds

Abstract: The effects of nose radius on stagnation and surface heat transfer rate along the surface are addressed in this research paper. Experiments are carried out in hypersonic shock tunnel, at hypersonic Mach number of 6.56 for 11.38° apex angle blunt cone with nose radius of 0.2R, base radius of R. Similarly, experiments are carried out at Mach 7.32 for 13.87° apex angle blunt cone models with nose radius of 0.18R′, base radius of R′. Test is performed at stagnation enthalpy of 1.4 and 2 MJ/kg with effective test time of 3.5 ms. Convective heat transfer measurements have been carried out on the test model at two different angles of attack, namely 0° and 5° with angle of rotation of 0°, 90°,180° with platinum thin film sensors. ANSYS-Fluent used to simulate the flow over the blunt models at different Mach numbers. The measured shock standoff distance from Schlieren visualization images compared with theory and computational fluid dynamic study for both configurations. The measured stagnation heating value is compared with theoretical value estimated using Fay-Riddell expression and numerical simulation. The measured heat transfer rate is higher for configuration 1 than configuration 2. The increases in heat transfer rate is due higher density ratio across the shock wave and the reduced shock layer thickness. The measured shock layer thickness is 2.06 mm for Mach 6.56 and 3.45 mm for Mach 7.32. The heat transfer rate is higher for Mach 6.56 as compared to Mach 7.32.

Thermoelastic damping in nonlocal rod using three-phase lag heat conduction model

Abstract: This manuscript studies thermoelastic damping of a longitudinally vibrating nanorod at small-scale. The heat conduction in the present work is constructed based on the three phase-lag heat conducti...

Trajectory Optimisation of Long Range and Air-to-Air Tactical Flight Vehicles

Abstract: This paper presents formulation and solution of long range flight vehicle and tactical air-to-air flight vehicle trajectory optimisation. The first case study is of a long range flight vehicle. Here an optimum steering program during powered phase has been evolved as control input for achieving maximum range with available propulsions in the presence of path and terminal constraints. The second case study is of a tactical flight vehicle for air-to-air application. Here a minimum flight time trajectory has been generated for covering a specified range pertaining to a specified air-to-air engagement by evolving pitch lateral acceleration as control input. Here also, there are many path and terminal constraints consisting of launch aircraft, pursuer, and evader. The studies have been carried out as part of system design activity of both flight vehicles. Both are real-life optimisation problems under several constraints. Through it is very difficult to solve such practical problems in flight dynamics using classical optimal control theory, it has been solved successfully using direct transcription method based on nonlinear programming. Rapid convergence has been achieved in four passes with minimum grids in first pass, to start with, and increasing the grids in subsequent passes. Solving such a real-life problem with proper convergence subjected to many constraints is claimed as novelty of present research. Defence Science Journal, Vol. 65, No. 2, March 2015, pp.107-118, DOI:http://dx.doi.org/10.14429/dsj.65.8238