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Wyszukujesz frazę "Singh, S. N." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Study of inline-slot ejector diffuser under varying ambient conditions: A passive infrared suppression device for ships
Autorzy:
Singh, L.
Singh, S. N.
Sinha, S. S.
Powiązania:
https://bibliotekanauki.pl/articles/117455.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
applications for navy
ejector diffuser
passive iInfrared suppression device
InfraRed (IR)
IR imaging
IR locking
Shear Stress Transport (SST)
Infrared Suppression System (IRSS)
Opis:
Passive infrared (IR) suppression device, commonly known as ejector diffuser, is an integral part of the defence system of a ship. The definitive role of passive IR suppressor to counter the IR tracking and locking of the ship has made them indispensable for any combat marine. The gas turbine exhaust gases are the leading heat source on a ship. The exhaust temperature of the gases ranges between 650K-850K. At such temperatures, the ship can be easily detected by the enemy through IR imaging. The role of the ejector diffuser is to (i) lower the gas turbine exhaust gases temperature to the limits (< 450K) such that the IR locking of the marine can be avoided, and (ii) recover static pressure such that the engine performance of the gas turbine is not affected. Ejector diffuser has the ability to entrain ambient air and allow mixing it with the exhaust gases thereby, lowering the temperature of the exhaust gases. However, the mixed exhaust gases temperature depends on the ambient air temperature which under extreme conditions can fluctuate from 273K to 323K. This temperature range can affect the temperature characteristics of an ejector diffuser. The present study undertakes the effect of ambient temperature on the performance of inline-slot ejector diffuser. The ambient temperature (T0) has been varied in the range 273K ≤ T0 ≤ 323K in the step of 10K. It has been found that the mass entrainment increases (≈ 8%) as the ambient temperature decreases. The core temperature at the exit decreases, from 457.58 K to 417.75K, with a decrease in the ambient temperature. However, no significant changes in static pressure recovery.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2020, 14, 2; 477-482
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An investigation of ship airwakes by scale adaptive simulation
Autorzy:
Shukla, S.
Singh, S. N.
Sinha, S. S.
Vijayakumar, C.
Powiązania:
https://bibliotekanauki.pl/articles/116802.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
applications for navy
ship airwakes
Scale Adaptive Simulation (SAS)
simulation
flow phenomena
turbulent structures
investigation by simulation
ship airwakes flow characteristic
Opis:
An early assessment of the ship airwakes flow characteristic is one of the most challenging tasks associated with the designing of vessels. The presence of ship airwake creates very complex flow phenomena due to the presence of strong velocity gradients in space and time and widely varying high levels of recirculation and turbulence. Under such condition, the landing and take-off operation of a helicopter over the ship helodeck is very complex and accurate prediction represents a computational challenge. We present time-accurate scale-adaptive simulation (SAS) of turbulent flow around a simple frigate ship to gain insight into the flow phenomena over the helodeck. Numerical analysis is carried out after several grids and time-steps refinement to ensure the spatial and temporal accuracy of the numerical data. The instantaneous iso-surface of eddy flow structures and vorticity have been analysed across the vertical and longitudinal plane. Results show good agreement with experimental data. Comparisons of mean quantities and velocity spectra show good agreement, indicating that SAS can resolve the large-scale turbulent structures which can adversely impact ship-helo combined operations. Overall, the SAS approach is shown to capture the unsteady flow features of massively separated ship airwake characteristics with reasonable accuracy.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2020, 14, 2; 471-475
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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