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A numerical investigation of the flame characteristics and mass burning rates of steady laminar diffusion flames established over methanol surface under co-flow configuration is presented. A numerical model that solves the transient, two-dimensional gas-phase governing conservation equations using global single-step reaction kinetics for methanol-air oxidation is employed for the present investigations...
In this work, we have studied the structural changes in soot precursor particles sampled from an isooctane/air rich premixed flame using Fourier transform infra red spectroscopy. Samples are extracted from different heights of the flame and dispersed in dichloromethane for ex-situ measurements in an infrared spectrometer. An absorption spectrum of mature soot collected from the same flame is also...
This study deals the effect of premixed charge energy on combustion characteristics of a direct injection diesel engine of 7.4 kW rated power at a constant speed of 1,500 rpm. The premixed charge energy is varied from 25.4 to 56.4 % under three different modes; (i) conventional diesel mode (ii) H2-diesel dual-fuel mode, and (iii) partially homogeneous charge compression ignition (PHCCI) mode. The...
Experimental analysis of a diesel engine gives only the global picture of the in-cylinder processes, through averaged quantities. These averages are sometimes global averages or in some cases taken at each crank angle. To understand the in-cylinder processes better, the distribution of scalars becomes very important. In this paper, Converge, a CFD-tool was used to simulate the closed cycle in-cylinder...
A numerical study is conducted to characterize the hydrogen- and syngas-assisted ignition of two JP-8 surrogates, a two-component surrogate and a six-component surrogate. The six-component surrogate has previously been found to accurately simulate the smoke point, volatility, flame temperature profiles, and extinction limits of JP-8, while the two component surrogates has been shown to reproduce the...
A multiple-gas sensor based on absorption spectroscopy technique using a super luminescent diode source of 1.5 μm is proposed and realized for combustion applications. This technique allows CH4 and CO2 gas sensing in bio-gas plant to monitor the quality of the gas. In this study, a solid Fabry–Perot etalon with a free spectral range of 517 GHz is also used and the detection limit is improved, allowing...
Modification of composite solid propellant burning rates becomes a requirement based on the necessities of a mission. Literature discusses about various burn rate modifiers which can modify the burning rates effectively. This paper attempts to understand the behavior and mechanism of (dry) activated charcoal (a recently reported burn rate modifier) in composite solid propellant combustion. Extensive...
Four different sizes of Indian high ash coal and char are investigated. A simultaneous thermal analyzer and mass spectrometer is used for the characterization of the coal and char samples and the identification of the volatiles evolved during the heating of the sample upto 1,050 °C under combustion cum gasification related conditions. The TG and DTA results are discussed for the investigations under...
One of the ways to mitigate fouling and slagging in downstream sections of boilers, power plants, and gas turbines employing coal combustion is to coat the boiler tubes with low surface energy materials. Such a coating not only reduces the surface energy but can potentially offer a rough surface as well. Hence, the simultaneous effects of surface energy and roughness on fly ash deposition need to...
Three-dimensional Direct Numerical Simulation (DNS) data of methane-air MILD combustion is analysed to study the behaviour of MILD reaction zones and to identify a suitable modelling paradigm for MILD combustion. The combustion kinetics in the DNS was modelled using a skeletal mechanism including non-unity Lewis number effects. The reaction zones under MILD conditions are highly convoluted and contorted...
For a launch vehicle, the base line aerodynamic coefficients are generated using wind tunnel tests at various Mach numbers, angles of attack and wind plane angles. Thereafter the contribution of differences in wind tunnel model and flight configuration, Reynolds number differences and Jet-on effect are quantified separately and included as incremental coefficients over the baseline data either...
Cocuring process is a unique characteristic of composite materials wherein multiple parts like stringers, ribs and spars are simultaneously cured and bonded to a composite skin resulting in an integral structure. It has many benefits like reduction in part count, elimination of stress concentration due to fastener holes in the cocured regions and reduced assembly time and related costs. However, the...
Turbulent flow in a mixed compression intake is investigated. The unsteady compressible Navier–Stokes equations are solved using a stabilized finite element method with 6-noded triangular element. The Spalart–Allmaras model is used for turbulence closure. For comparison, the laminar flow is studied as well. A bleed of 6 % is utilized to overcome the start-up problem of the intake. The effect of back...
Cryogenic propulsion systems using liquid hydrogen and liquid oxygen propellant combination are used in satellite launch vehicles in view of the higher specific impulse (I SP ). Due to extreme low temperature of cryogenic propellant and low density and explosive nature of LH 2 , the development of cryogenic propulsion system is very complex and time consuming. In ISRO...
Reusable launch vehicle (RLV) is a goal pursued by different aerospace agencies, world-wide. Indian space research organization is also one among them. This paper covers the challenges faced and the solutions developed for control law design of a typical re-entry vehicle. The first stage of the test vehicle, used for technology demonstration mission, is a conventional solid rocket motor. The second...
Unmanned aircraft systems (UAS) have been widely recognised as efficient platforms to perform surveillance and reconnaissance missions. The promising roles played by UAS in peace time missions coupled with their lower operating cost motivate the military world to evolve doctrines and concept of operations with UAS as the main elements in the future integrated network centric digital battlefield environment...
A bstract ISRO Satellite Centre (ISAC) is a premier research and development Centre for satellite systems under the Indian Space Research Organization. Over the last four decades, ISAC has achieved remarkable success in the realization of state-of-the-art spacecraft missions covering wide spectrum of applications and services in the areas of television broadcasting, radio networking, VSAT...
A summary of the results obtained using the flow solver HiFUN for the 3D High lift NASA Trapezoidal wing are presented. Hybrid unstructured grids have been used for the computations. Grid converged solution obtained for the clean wing and the wing with support brackets, are compared with experimental data. The ability of the solver to predict critical design parameters associated with the high...
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