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.

Design and Analysis of MEMS-based Microballoon Actuators for Aerodynamic Control of Flight Vehicles

Abstract: The development of microelectromechanical systems (MEMS) technology and the suitability and compatibility of sizes of microactuators with the boundary layer thickness fueled the active flow separation control to gain the air flow momentum for the last few years. The present paper deals with the development of a robust, largedeflection, and large-force MEMS-based microballoon actuator for aerodynamic control of flight vehicles such as projectiles, micro air vehicles, aircrafts, etc. Experiments were carried out on the scaled-up models for different input pressure conditions to study the response of microballoon actuator. To evaluate the performance of the microballoon actuators, simulation studies on MEMS scale models were conducted in the CoventorWare environment. Simulation studies involving static and dynamic analyses have been carried-out on the microballoon actuator models. Various geometric and input parameters influencing the behaviour of the microballoon actuator were investigated. It has been observed that a maximum deflection of 1.2 mm to 1.5 mm can be achieved using microballoon actuators and the maximum operational frequency of 60 Hz to 80 Hz can be used for the operation of microballoon actuators. Also, the sizes of the microballoon actuators designed are compatible and suitable to be used in turbulent boundary layer of aerodynamic flight vehicles. Defence Science Journal, 2009, 59(6), pp.642-649 , DOI:http://dx.doi.org/10.14429/dsj.59.1570

Numerical simulation of fairing separation test for hypersonic air breathing vehicle

Abstract: Fairings are provided to cover hypersonic air breathing vehicle to protect it from adverse aerodynamic loading and kinetic heating. Separation dynamics of fairings is an important event in the launch of vehicle. Extensive computational fluid dynamics simulations are carried out for the design of fairings and vehicle and selection of time sequences of various separation events. A ground test of fairing separation is conducted in the sled facility to check the structural integrity and functionality of various separation mechanisms and flight hardware. Simulations have been carried out to study the separation dynamics of fairings at test conditions using grid-free Euler solver to get the aerodynamic loads and the loads are integrated to get the trajectory of fairings. The aerodynamic loads are provided to verify the structural integrity of various components and the trajectory of panels is used in the test planning. The pressure distributions on the vehicle are compared with the test results.

Storable Hypergolic Solid Fuel for Hybrid Rocket Engines

Abstract: A solid fuel was synthesised by condensing aniline with furfuraldehyde. The product was directly cast in the rocket motor casing. After curing a hard solid mass was obtained. This was found to have good hypergolicity with RFNA (Red Fuming Nitric Acid), good storability at room temperature and the mechanical properties. The paper presented the techniques of casting, ignition delay measurements and indicates the future programme for this study.

Physical layer security using an adaptive modulation scheme for improved confidentiality

Abstract: Establishing secured communication among the intended users of wireless networks is a major concern. Especially, providing confidentiality is a critical requirement in a wireless communication system which is more susceptible to eavesdroppers. Prevailing cryptographic methods were proven to meet the security needs to some extent. Sophisticated encryption techniques cannot be always deployed in wireless devices, where the resources are limited. However, physical layer security is recently emerging into a promising paradigm to aid security in wireless networks by exploiting the dynamics of wireless channel. In this study, a physical layer security technique was proposed to enhance confidentiality which selects the modulation type adaptively, based on both channel signal-to-noise ratio and phase between transmitter and receiver. The performance of the proposed technique is evaluated for two types of eavesdroppers such as random and intelligent attackers through simulations. The proposed method improves confidentiality and throughput while maintaining the targeted symbol error rate than the existing algorithms.

Missile aerodynamics at high angles of attack - A prediction code

Abstract: A computer code has been developed for estimating the aerodynamic characteristics of cruciform missile configurations at high angles of attack (upto 30xB0;), with13; arbitrary control deflections (xB1;25xB0;) and non-zero roll angle (0 xA3; 0 xA3; 90xB0;). The prediction code is based on the equivalent angle of attack technique. It combines semi-empirical methods, theoretical methods and correlated data bases. The code has been validated over a wide range of missile configurations and flight parameters. The overall capabilities of the code have been compared with nine other missile aeroprediction codes. These studies have demonstrated the capability of the code for preliminary design of missile configurations.