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.

COVSACK: an innovative portable isolated and safe COVID-19 sample collection kiosk with automatic disinfection

Abstract: The Corona VIrus Disease 2019 (COVID-19) is one of the significant medical disaster that changed the life of humankind in the 21st century The deadly virus is transmittable from infected person, through his nasal droplets, to surrounding people among whom, the healthcare personnel are the utmost affected The present article brings out an innovative chamber, which is used for collection of throat, or nasal swabs/samples for diagnosis of COVID-19 suspected persons The chamber, called COVid SAmple Collection Kiosk (COVSACK), eliminates the transmission of the deadly virus to the health care personnel while collecting the sample The kiosk is designed based on CFD simulations for effective spread of disinfectant in fine droplet form, built with a lightweight composite that is sustainable in extreme weather conditions and the kiosk can be easily sanitized within 3 min after sample collection The chamber is first positioned in ESI Hospital, Hyderabad, and other hospitals and diagnostics centres across India, extensively being used for testing the COVID-19 patients at a faster rate, with a drastic reduction in use of personal protection equipment (PPE) This technological innovation, to certain extent, has changed the way the testing of COVID-19 patients carried out in the country

Fabrication and Ablation Studies of 4D C/SiC Composite Nozzle Under Liquid Propulsion

Abstract: 4D C/SiC composite nozzle was fabricated using LSI and characterized for mechanical, thermal, and ablation properties. Average flexural and compressive strengths in the Z-direction were found to be 119 and 110 MPa, while in the U-, V- and W-directions, they were 99 and 55MPa, respectively. Coefficient of thermal expansion was found to be varied in the range 0–1.5 × 10−6/°C (25–1050°C), while thermal diffusivity was 40–5 mm2/s (25–1200°C). Ablation behavior of the nozzle was evaluated under UH25/N2O4 propulsion system for 30 s. The overall mass erosion rate and the linear ablation rate were found to be 0.119 kg/m2s and 0.05 mm/s, respectively.

A robust and high precision optimal explicit guidance scheme for solid motor propelled launch vehicles with thrust and drag uncertainty

Abstract: A new nonlinear optimal and explicit guidance law is presented in this paper for launch vehicles propelled by solid motors. It can ensure very high terminal precision despite not having the exact knowledge of the thrust–time curve apriori. This was motivated from using it for a carrier launch vehicle in a hypersonic mission, which demands an extremely narrow terminal accuracy window for the launch vehicle for successful initiation of operation of the hypersonic vehicle. The proposed explicit guidance scheme, which computes the optimal guidance command online, ensures the required stringent final conditions with high precision at the injection point. A key feature of the proposed guidance law is an innovative extension of the recently developed model predictive static programming guidance with flexible final time. A penalty function approach is also followed to meet the input and output inequality constraints throughout the vehicle trajectory. In this paper, the guidance law has been successfully validated from nonlinear six degree-of-freedom simulation studies by designing an inner-loop autopilot as well, which enhances confidence of its usefulness significantly. In addition to excellent nominal results, the proposed guidance has been found to have good robustness for perturbed cases as well.

Comparison of fracture models to assess the notched strength of composite/solid propellant tensile specimens

Abstract: Modifications are made in the well-known inherent flaw model as well as in the stress fracture models for accurate prediction of notched tensile strength of composite laminates containing holes or slits. To examine the adequacy of these modifications, fracture data on different composite materials reported in the literature are considered. The notched strength estimates from the present fracture models are found to be close to the existing test results. An attempt is made to correlate the fracture data of center crack tension specimens made of nitramine and HTPB-based propellant materials. The present analysis results from the above simple models are found to be in good agreement with test results. This study confirms the applicability of the above three fracture models to solid propellant materials having relatively low stiffness and strength. Since the notched strength estimates of composite/solid propellant tensile specimens are close to the test results, any one of them can be utilized while evaluating the notched tensile strength of specimens.

Experimental study on mixing enhancement in two dimensional supersonic flow

Abstract: Studies on mixing enhancement with two dimensional (2D) lobed nozzle have been conducted in a dual stream supersonic flow facility. The distributions of momentum flux, stagnation pressure and stagnation temperature across a plane at different axial distances from the nozzle exit were considered as a measure of mixing. The results indicated an enormous enhancement in mixing when 2D lobed nozzle was employed in comparison with conventional plain 2D nozzle. The enhanced mixing performance could be attributed to the large scale axial vortices observed in the flow-field of subsonic lobed nozzles by earlier investigators.