Tradeoffs in Jet Inlet Design: A Historical Perspective

Sóbester, András

doi:10.2514/1.26830

Cited by 51 publications

(34 citation statements)

References 61 publications

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“…The exit dynamic pressure (q e ) is calculated by first assuming an exit area and a discharge coefficient. The discharge coefficient itself depends on the exit to inlet dynamic pressure ratio and the flow exit angle [6]. The flow exit angle is assumed to be 30°f or which _ m = 0.827 kg/s and n = 0.14.…”

Section: Aspects Of Oil Cooler Duct Designmentioning

confidence: 99%

Investigation of Engine Oil-cooling Problem during Idle Conditions on Pusher Type Turbo Prop Aircraft

Premkumar

Chakravarthy

Subramanian

et al. 2016

International Journal of Turbo &Amp; Jet-Engines

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Aircraft engines need a cooling system to keep the engine oil well within the temperature limits for continuous operation. The aircraft selected for this study is a typical pusher type Light Transport Aircraft (LTA) having twin turbo prop engines mounted at the aft end of the fuselage. Due to the pusher propeller configuration, effective oil cooling is a critical issue, especially during lowspeed ground operations like engine idling and also in taxiing and initial climb. However, the possibility of utilizing the inflow induced by the propeller for oil cooling is the subject matter of investigation in this work. The oil cooler duct was designed to accommodate the required mass flow, estimated using the oil cooler performance graph. A series of experiments were carried out with and without oil cooler duct attached to the nacelle, in order to investigate the mass flow induced by the propeller and its adequacy to cool the engine oil. Experimental results show that the oil cooler positioned at roughly 25 % of the propeller radius from the nacelle center line leads to adequate cooling, without incorporating additional means. Furthermore, it is suggested to install a NACA scoop to minimize spillage drag by increasing pressure recovery.

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Section: Aspects Of Oil Cooler Duct Designmentioning

confidence: 99%

Investigation of Engine Oil-cooling Problem during Idle Conditions on Pusher Type Turbo Prop Aircraft

Premkumar

Chakravarthy

Subramanian

et al. 2016

International Journal of Turbo &Amp; Jet-Engines

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“…4 However, a large number of aircraft do not use this approach even though it is an idea that has been around well before they were created. 8 For example, both the Vought F-8 Crusader and the General Dynamics F-16 both use fixed normal shock inlets. At first glance, it may appear that the designers were trying to save on cost and keep the simple, cheaper inlet design.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Supersonic Inlet Topology on the Installed Performance of Tubofan Engines

Palma

Takahashi

2016

16th AIAA Aviation Technology, Integration, and Operations Conference

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This study explores the system level design impacts of differing supersonic inlet topology. Historically, for Mach 2 flight, variable ramp angle external compression inlets have been preferred over normal shock inlets on the basis of pressure recovery. However, from a system design perspective, is inlet pressure recovery everything? We compare a variety of low-bypass ratio turbofan engines, modelled with NASA's Numerical Propulsion System Integration (NPSS), that can propel a F-16-inspired tactical fighter aircraft. We compute installed performance by applying installation limits (buzz and distortion) and losses (bleed, bypass, spillage, and total pressure recovery) as suggested by the USAF Performance of Installed Propuslion Systems (PIPSI) protocol. Our design study matrix comprises three different engines (Bypass Ratio of 0.5, 1.0, and 1.5) matched to one of three inlet topologies (normal shock, fixed ramp external compression and variable ramp external compression) scaled to any of five possible capture areas. We found that the variable ramp external compression inlet was unforgiving of higher bypass ratio engines. Compared to the robust nature of the normal shock inlet leads the authors to believe that the normal shock inlet, not the complex variable geometry ramp inlet, may be the superior choice for many supersonic propulsion design applications. NomenclatureA ∞ = Actual Inlet Capture Area (Freestream conditions) representing the flow through the inlet, ft 2 A c = Reference Area of Flow that passes through the Inlet, the "highlight area," ft 2 AB = Afterburner C D = Total Drag Coefficient (normalized on Reference Capture Area, Ac) BPR = Bypass Ratio CD spill = Spill Drag Coefficient (normalized on Reference Capture Area, Ac) CD bleed = Bleed Drag Coefficient (normalized on Reference Capture Area, Ac) CD bypass = Bypass Drag Coefficient (normalized on Reference Capture Area, Ac) D = Total Drag Force, lbf FPR = Fan Pressure Ratio M = Mach Number MFR = Mass Flow Ratio (ratio of bypass duct mass flow to core mass flow) OPR = Overall Pressure Ratio PLA = Power Lever Angle p t = Total Pressure, lbf/ft 2 P s = Specfic Excess Power ROC = Rate of Climb, ft/min SR = Specific Range, nm/lbf T = Thrust, lbf TIT = Turbine Inlet Temperature, °R tsfc = Thrust-Specific-Fuel-Consumption, lbm/(lbf-hr) V ktas = Knots True Airspeed, nm/hr

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“…It creates excessive vibrations in tall buildings and other wind‐sensitive structures, thus increasing the risks of losing their structural integrity . In case of an aircraft engine, wind (especially the crosswind) modifies interaction of the airflow with engine inlet structures, where geometry of the intake defines parameters of the airflow ingested by the engine and resistance to flow separation at varying operational conditions …”

Section: Introductionmentioning

confidence: 99%

Novel health monitoring technology for in‐service diagnostics of intake separation in aircraft engines

Gelman

Petrunin

Parrish

et al. 2020

Struct Control Health Monit

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Summary Diagnostics and elimination of airflow separation effects draw essential attention of researchers in the areas of energy generation, civil engineering, and aerospace due to unwanted and harmful interaction of separated airflow with different structures. In aviation, distortion of the intake airflows of an aircraft engine, known as intake separation, not only reduces the efficiency of the engine due to decrease in air intake but also interacts with engine structural components, for example, blades, significantly increasing their vibration. This leads to fatigue and subsequent accelerated failure of these components. Therefore, health monitoring and diagnostics of the intake separation effects using structural health monitoring (SHM) framework are of high importance for ensuring both optimal engine performance and its safe operation. In the present paper, a novel health monitoring technology based on advanced signal processing, the integrated higher order spectral technique, is applied for the first time in worldwide terms for in‐service intake separation diagnostics in aircraft engine using casing vibration data.

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Tradeoffs in Jet Inlet Design: A Historical Perspective

Cited by 51 publications

References 61 publications

Investigation of Engine Oil-cooling Problem during Idle Conditions on Pusher Type Turbo Prop Aircraft

Investigation of Engine Oil-cooling Problem during Idle Conditions on Pusher Type Turbo Prop Aircraft

The Effects of Supersonic Inlet Topology on the Installed Performance of Tubofan Engines

Novel health monitoring technology for in‐service diagnostics of intake separation in aircraft engines

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