Effects of forward-flight speed on plume flow and infrared radiation of IRS-integrating helicopter |
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Authors: | Zongyao YANG Jingzhou ZHANG Yong SHAN |
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Institution: | Key Laboratory of Thermal Management and Energy Utilization of Aircraft of Ministry of Industry and Information Technology, College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China |
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Abstract: | To address deeper understandings about the aero-thermal performance of an integrating infrared suppressor under more realistic situations, a numerical investigation is motivated in the current study, concerning the effects of forward-flight speed on exhaust plume flow and infrared radiation of the Infrared Suppressor-integrating (IRS-integrating) helicopter, wherein the forward-flight speed is changed from 0 m/s (hover state) to 100 m/s, while both the engine exhaust parameters and the main-rotor operation parameters remains unchanged during different forward-flight velocities. The results show that the interaction between forward-flight flow and downwash flow alters the exhaust plume development and the internal flow inside the IRS-integrating rear fuselage more complicatedly, tightly dependent on the forward-flight speed. Of particular concern is the situation where the forward-flight flow has nearly the same level as the downwash flow, the hot mixing flow could possibly interacts with the helicopter rear fuselage to play a local heating effect. With the increase of forward-flight speed, the ejection coefficient is generally increased and the average exhaust temperature of mixing flow is decreased, leading to a reduction of the infrared radiation intensity of exhaust plume in 3–5 μm band. However, the influence of forward-flight speed on the overall infrared radiation intensity of IRS-integrating helicopter is conjectured not monotonous due to the complicated interaction between forward-flight flow and downwash flow. Under high-speed forward-flight states, the overall infrared radiation intensity of the IRS-integrating helicopter in 3–5 μm band is reduced with the increase of forward-flight speed. With respect to 3–5 μm band, the forward-flight speed has little effect on the infrared radiation in 8–14 μm band. |
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Keywords: | Exhaust plume Forward-flight speed Helicopter Infrared radiation Integrating infrared suppressor |
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