Progress in helicopter infrared signature suppression

Zhang, Jingzhou; Pan, Chengxiong; Shan, Yongkui

doi:10.1016/j.cja.2014.02.007

Cited by 40 publications

(9 citation statements)

References 37 publications

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“…In fact, lobed geometries were widely used before in combustion chambers to improve their efficiency and reduce their emission of pollutants [13,14]. Also, they have been integrated into ejectors of aircraft engines to improve their thrust [15,16], to attenuate their noise level [17], or to attenuate their infrared signature in military application [18].…”

Section: Introductionmentioning

confidence: 99%

Passive control strategy for mixing ventilation in heating mode using lobed inserts

Bragança

Sodjavi

Meslem

et al. 2016

Energy and Buildings

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Research Highlights: Flow pattern and thermal comfort are analyzed in a room under mixing ventilation > A vertical hot jet is generated by a conventional ceiling multi-cone diffuser > The effect of inserted lobes into the conventional diffuser is analyzed > Significant improvement of thermal comfort is achieved due to jet induction increase > It was not observed a significant increase in pressure drop and noise ABSTRACTThe main purpose of ventilation systems is to satisfy the need of occupants in terms of thermal comfort and air quality. In the case of mixing ventilation, based on the use of jets from one or from multiple diffusers placed in the room, the fresh air and the thermal loads should be distributed in the entire occupied zone. Therefore, the design of the diffusers must aim, beyond aesthetic aspect, the ability to provide a good mixing between the jet and the ambient air. Enhancement of jet induction by means of lobed inserts into a diffuser, was recently proposedin an European patent as a promising and low-cost solution for improving the performance of HVAC systems. In this paper, an experimental investigation on jet characteristics and thermal comfort generated by a classical multi-cone ceiling-mounted diffuser is proposed. Its performance is compared with the same diffuser equipped with lobed inserts. A simplified heated manikin simulates the presence of a human body in the test room. Airflow pattern from the diffuser and its interaction with the manikin were analyzed with whole-field PIV technique.Thermal comfort was analyzed based on traditional pointwise measuring probes and on the standard ISO 7730. It is revealed that the thermal comfort was significantly improved using the lobed diffuser compared to the conventional one, without increase of pressure drop and sound pressure levels.

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Section: Introductionmentioning

confidence: 99%

Passive control strategy for mixing ventilation in heating mode using lobed inserts

Bragança

Sodjavi

Meslem

et al. 2016

Energy and Buildings

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“…Авторами досліджень [6] на основі результатів чисельного моделювання запропоновані різні орієнтації напрямку відведення вихлопних газів, що конструктивно мають забезпечуватись різними кутами установки на борт вертольота ЕВП. Авторами передбачається, що інтенсивність рівня інфрачервоного випромінювання буде змінюватись в залежності від кута напрямку відведення вихлопних газів.…”

Section: дослідження існуючих рішень проблемиunclassified

Development of method of testing a set of screen-exhaust devices in the helicopter Mi-8MSB-B

Kinaschuk

2020

TAPR

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Використання екранно-вихлопних пристроїв (ЕВП) в газотурбінних двигунах (ГТД) вертольотів є одним із ефективних засобів пасивного захисту 2. Об'єкт дослідження та його технологічний аудит Об'єктом досліджень є комплект екранно-вихлопних пристроїв (ЕВП) у складі вертольоту Мі-8МСБ-В (український варіант модернізації радянського багатоцільового вертольота Мі-8, розроблений акціонерним товариством «Мотор Січ», м. Запоріжжя, Україна).

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“…4 Lobed mixers are widely used on aerospace engine exhaust systems due to their ability to increase nozzle thrust and efficiently mix high temperature exhaust flow with cooler ambient air, thus lowering noise and plume infrared (IR) radiation. 2,[5][6][7][8][9][10] The adoption of mixer-ejectors represented a paradigm shift in ejector design; previous designs utilised viscous forces to transfer energy from the hot stream to entrain a cooler secondary stream. 8 Substantial axial length was required to ensure mixing since the method relied on viscous shear layer mixing of streams.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of helicopter engine exhaust through scaled experiments using stereoscopic particle image velocimetry

Teo

Wong

Lee

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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Helicopter engines are often mounted atop the fuselage to keep the aircraft footprint small and optimal for operations. As a result, hot gases produced by the engines may inadvertently impinge upon the tail boom or dissipate inefficiently that compromises on operation safety. In this study, a scaled fuselage model with a hot air blower was used to simulate hot exhaust gases. The velocity field immediately outside the exhaust port was measured through stereoscopic particle image velocimetry to capture the trajectory and flow behaviour of the gases. Two cases were considered: freestream to exhaust velocity ratios of 0 (no freestream velocity) and 0.46 (co-flowing free stream), respectively. The formation of a counter-rotating vortex pair was detected for both cases but were opposite in the rotational sense. For the case without freestream, the plume formed into a small “kidney” shape, before expanding and dissipating downstream. For the case with freestream, the plume formed into a slenderer and more elongated “reversed-C” shape as compared to the case without freestream. It also retained its shape further downstream and maintained its relative position. These observations on the trajectory and shape of plume provide basis to understanding the nature and interaction of the plume with its surroundings.

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Progress in helicopter infrared signature suppression

Cited by 40 publications

References 37 publications

Passive control strategy for mixing ventilation in heating mode using lobed inserts

Passive control strategy for mixing ventilation in heating mode using lobed inserts

Development of method of testing a set of screen-exhaust devices in the helicopter Mi-8MSB-B

Characteristics of helicopter engine exhaust through scaled experiments using stereoscopic particle image velocimetry

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