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.

Polynomial Guidance Law for Dual-Seeker Interceptors

Abstract: A polynomial-based guidance law is proposed for interception of a stationary target by a dual-seeker interceptor. The guidance law governs the desired look-angle profile as a cubic polynomial of th...

Design and Analysis of Rotating Detonation Wave Engine

Abstract: Rotating detonation wave engine (RDE) would be the futuristic engine for air-breathing missile systems and gas turbine systems (aero and stationary applications). The continuous operation of RDE with an operating frequency of 3–15 kHz is attractive for propulsion systems based on rocket, ramjet and turbojet engines. The cell size is the characteristic dimension of the cellular pattern of a propagating detonation wave. The cell size is found to depend strongly on the choice of fuel and oxidizer, its equivalence ratio, initial temperature and initial pressure. Some empirical relations based on cell size are used to design the present detonation combustor. Hydrogen is chosen as the fuel, while air is selected as the oxidizer. The RDE hardware has been realized, and the test facility is being modified at NCCRD, IIT, Madras to carry out static tests. The analysis of the RDE combustor without the nozzle is carried out using the “pressure history model” reported in literature. As the hydrogen fuel and air are entering as two different streams perpendicular to each other, a simple mixing analysis has been carried out to evaluate the mixture properties ahead of the detonation wave. The Chapman–Jouguet (CJ) detonation computations are carried out using the detonation tool box runs in conjunction with Cantera software assuming chemical equilibrium. The fuel-based specific impulse resulted from the present analysis for our configuration using H2-air is 4733 s compared to a value of 4706 s reported in literature for a stoichiometric composition. The same model has been used to evaluate the C2H4-air system. The specific impulse of our study is 2111 s compared to 1975s reported in literature for the fuel-based equivalence ratio of 0.5. This has given credence to the results of the analytical work.

Mechanical property anisotropy in superalloy El-929 directionally solidified by an exothermic technique

Abstract: Directional solidification (DS) of the nickel-based superalloy El-929 was carried out by employing the exothermic technique for preparing several 150 mm long x 55 mm diameter rods. Specimens machined from blanks cut at 0, 45, 75 and 90 deg to the chill surface were tensile and stress-rupture tested at different temperatures. The air-melted DS alloy, when loaded parallel to the growth direction, shows considerable improvement in stress-rupture life and tensile ductility as compared with the vacuum induction melted, forged and heat-treated alloy. However, these property advantages rapidly degrade with the increasing deviation of the load axis from the growth direction.

A Nonlocal Continuum Mechanics Model for Analyzing the Terahertz Flexural Wave Dispersion Characteristics of a Monolayer Graphene Embedded in Elastic Medium

Abstract: This article presents the strong, nonlocal scale effect on the terahertz flexural wave dispersion characteristics of a monolayer graphene sheet (GS), which is embedded in elastic medium. The chemical bonds are assumed to be formed between the GS and the elastic medium. From the spectrum analysis, we found that the elastic matrix highly affects the flexural wave mode and rapidly increases the frequency band gap of flexural wave. The nonlocal elasticity calculation shows that the wavenumber escapes to infinite at a certain frequency and the corresponding wave velocity tends to zero at that frequency, indicating localization and stationary behavior.

Thermal Design and Testing of External Protuberance of Hypersonic Carrier Vehicle Airframe

Abstract: Hypersonic carrier vehicle airframe experiences high rate of heat transfer caused by aerodynamic heating due to very high-speed flow during flight. A wire tunnel over the carrier vehicle is used to accommodate the communication and electric cables routed along the external surface of rocket motor casing from electronics packages section to rear part of the carrier vehicle. The wire tunnel leading edge forms an external protuberance. The protuberances are subjected to severe heating during the flight, especially at hypersonic speed. Thermal design of the protuberance structure is imperative to ensure safe operation in the severe thermal environment experienced during flight. This paper describes the thermal design of wire tunnel protuberance. Further, the design of wire tunnel assembly is ascertained by thermal test conducted in the infrared heating facility for aerodynamic heating condition corresponding to the flight trajectory.