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.

Temperature monitoring system with remote calibration capability

Abstract: This paper proposes a novel implementation of self-calibration in a temperature monitoring system that employs thermocouple as a temperature sensor for propellant and highly inflammable storage facilities where human frequent intervention for calibration of temperature sensors is not affordable. In the proposed design, we have implemented a comparison methodology for calibration of these thermocouples. To realize this, a Peltier heater has been used as a heat source whose temperature is controlled by a micro-controller through MOSFET. A pair of thermocouples with different accuracies is mounted on each Peltier heater and the temperature difference between them is measured subsequently in steps. Flexibility to access the system both in wireless mode (using ZigBee module) or wired mode (using ETHERNET module) has been provided. A graphical user interface has been developed in LabVIEW to monitor the temperature, calibrate the thermocouples and also to simultaneously store the data. A detailed description of the system and relevant test results have been presented in the paper.

CFD Methods in High-Speed Airbreathing Missile Propulsion Design

Abstract: Application of CFD tools in the design and analysis of high-speed airbreathing systems is described. Three-dimensional Navier-Stokes equations are solved along with SST-k-ω turbulence model. Lagrangian particle tracking method for kerosene droplet and single-step chemical reaction based on fast chemistry is used to model kerosene–air reaction. The computational tool is extensively validated against reliable experimental data before applying to design exercise. Better insight obtained from numerical simulations about the mixing and combustion process inside the combustor has enabled the placement of fuel injection struts and the injectors to obtain optimized combustor performance and benign thermal environments for a flight-sized hydrocarbon-fuelled scramjet combustor. Computed wall pressure matches nicely with experimental data for both non-reacting and reacting flows. Computed convective heat flux obtained through well-resolved thermal boundary layer simulations is used in the thermo-structural analysis of the scramjet combustor. End-to-end simulations integrating both external (non-reacting) and internal (reacting) flow are carried out of a complete hypersonic airbreathing vehicle to obtain complete aerodynamics and propulsion parameters of the vehicle for mission design. The evaluated installed air intake performance in terms of pressure recovery and mass capture ratio matches very well with experimental data. For higher angles of attack, windward and leeward side intakes show different performances, and leeward side intake experiences subcritical operation faster. The interaction between forebody boundary layer and intake shock system causes significant spillage. The starting and unstarting characteristics of a hypersonic intake are evaluated through unsteady RANS simulations. Both started flow and unstarted flow with large pressure oscillation are captured for different Mach numbers. The use of CFD tools has reduced the dependence of experimental testing in the design of high-speed airbreathing Propulsion Systems.