Numerical simulation of the airflow over a military aircraft with active intake

Triantafyllou, T.; Nikolaidis, Theoklis; Diakostefanis, Michail; Pilidis, Pericles

doi:10.1177/0954410016651294

Cited by 4 publications

(13 citation statements)

References 7 publications

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“…For validation purposes, the predictions generated by the proposed plume model were compared against CFD solutions for fully expanded (Figure 4) and under-expanded nozzle exit conditions [40] ( Figure 5). In the fully expanded case, jet exhaust velocity was 550m/s, exhaust temperature was 750 K, ambient temperature 288 K and flight Mach number 0.9.…”

Section: Plume Modelmentioning

confidence: 99%

Effects of Propulsion System Operation on Military Aircraft Survivability

Antonakis

Nikolaidis

Pilidis

2019

Journal of Aircraft

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The recent advances in Infra-Red (IR) weapon technology have dramatically altered the rules of air combat leading to a consistent departure from 'traditional' Energy-Maneuverability philosophy in aircraft design, prioritizing stealth and sophisticated armament instead. In this modern aerial warfare environment, it is obvious that new techniques need to be applied to properly assess aircraft survivability and produce successful designs for aircraft propulsion systems. The present study focuses on the development of such a methodology, which contrary to related work in the field includes considerations for both aircraft IR signature and missile/aircraft kinematic performance. An aircraft IR signature model is constructed using a collection of methods for area & temperature estimation and exhaust plume modelling; the latter is combined with missile-vs-aircraft and aircraft-vsaircraft simulations to quantify aircraft survivability in the form of missile & aircraft lethal zones. The proposed methodology is applied to a study on propulsion system effects on aircraft survivability, in which a comparison between different engine configurations is performed: In the scenarios examined, IR signature at cruise conditions and maximum-power thrust performance are identified as key parameters for aircraft combat performance. Nomenclature (Nomenclature entries should have the units identified) A = Area AB = Afterburner

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Section: Plume Modelmentioning

confidence: 99%

Effects of Propulsion System Operation on Military Aircraft Survivability

Antonakis

Nikolaidis

Pilidis

2019

Journal of Aircraft

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“…A numerical simulation of the airflow over the examined military aircraft has been accomplished and reported in Ref. 3. The tested conditions refered to 33 different aircraft flight scenarios:…”

Section: Total Pressure Distortion Profilesmentioning

confidence: 99%

“…The CFD predicted total pressure profile at the AIP for this specific aircraft flight attitude is presented in Fig. 2 (3) and the CFD predicted values of total pressure at the 8 points of the 1st ring from the hub, are shown on Table 1.…”

Section: •6m Flight Attitude With 8° Aoa and 16° Aossmentioning

confidence: 99%

“…. Profiles of total pressure (right part) and total pressure recovery (left part) at the AIP for the 0•6M Flight with 8˚ AOA and 8˚ AOSS (3) .…”

Section: •6m Flight Attitude With 8° Aoa and 16° Aossmentioning

confidence: 99%

“…The total pressure profiles at the AIP for these flight attitudes are presented in Figs 8 and 9 respectively. Profiles of Total Pressure (upper part) and Total Pressure Recovery (lower part) at the AIP for the 0•6M Flight with 8˚ AOA and 0˚ AOSS (3) . As it can be seen the former presents a wide circumferentially area of dark blue which represents the low pressure area with considerable variation in the value of total pressure (more than 50%).…”

Section: Effect Of Aoa and Aoss On Average Circumferential Extentmentioning

confidence: 99%

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Total pressure distortion levels at the aerodynamic interface plane of a military aircraft

et al. 2015

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Military aircrafts are often subjected to severe flight maneuvers with high Angles-of -Attack (AOA) and Angles of Sideslip (AOSS). These flight attitudes induce non-uniform in flow conditions to their gas turbine engines which may include distortion of inlet total pressure and total temperature at the Aerodynamic Interface Plane (AIP). Operation of the downstream compression system with distorted inflow typically results in reduced aerodynamic performance, reduced stall margin, and increased blade stress levels. In the present study the steady state total pressure distortion induced to the Aerodynamic Interface Plane due to the aircraft’s flight attitude have been estimated in terms of distortion descriptors. The distorted conditions at the interface between the intake and the engine have been predicted by using Computational Fluid Dynamics (CFD), where 33 different aircraft flight attitudes have been tested. Based on the obtained results the effect of Angle-of-Attack (AOA) and Angle of Side Slip (AOSS) on the distortion descriptors have been studied. The results showed that the distortion effect becomes more pronounced whenever this specific airframe configuration is exposed to incoming flow with an AOSS. Among the tested cases, the greatest total pressure defect at the AIP in terms of difference from the average value and of circumferential extent was calculated for the flight attitudes of 0·35M flight with 0° AOA and 8° AOSS and 0·35M fight with 16° AOA and 16° AOSS.

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Stability assessment of an airflow distorted military engine’s FAN

Triantafyllou

Nikolaidis

Diakostefanis

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part G:

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Military aircraft are often subjected to severe flight maneuvers with high Angles of Attack (AOA) and Angles of Sideslip (AOSS). These flight attitudes induce non-uniformity in flow conditions to their gas turbine engines which may include distortion of inlet total pressure and total temperature at the Aerodynamic Interface Plane (AIP). Operation of the downstream engine's compression system may suffer reduced aerodynamic performance and stall margin, and increased blade stress levels. The present study presents a methodology of evaluating the effect of inlet flow distortion on the engine's fan stability. The flow distortion examined was induced to the AIP by means of changing the aircraft's flight attitude. The study is based on the steady state flow results from 27 different flight scenarios that have been simulated in CFD. As a baseline model geometry an airframe inspired by the General Dynamics/LMAERO F-16 aircraft was chosen, which has been exposed to subsonic incoming airflow with varying direction resembling thus different aircraft flight attitudes. The results are focused on the total pressure distribution on the engine's (AIP) face and how this is manifested at the operation of the fan. Based on the results, it was concluded that the distorted conditions cause a shift of the surge line on the fan map, with the amount of shift to be directly related to the severity of these distorted conditions. The most severe flight attitude in terms of total pressure distortion, among the tested ones, caused about 7% surge margin depletion comparing to the undistorted value.

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Numerical simulation of the airflow over a military aircraft with active intake

Cited by 4 publications

References 7 publications

Effects of Propulsion System Operation on Military Aircraft Survivability

Effects of Propulsion System Operation on Military Aircraft Survivability

Total pressure distortion levels at the aerodynamic interface plane of a military aircraft

Stability assessment of an airflow distorted military engine’s FAN

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