The effect of doors and cavity on the aerodynamic noise of fuselage nose landing gear

2021 ◽  
pp. 1475472X2110032
Author(s):  
Yongfei Mu ◽  
Jie Li ◽  
Wutao Lei ◽  
Daxiong Liao
Keyword(s):  
Separated Flow ◽  
Leading Edge ◽  
Landing Gear ◽  
Aerodynamic Noise ◽  
Sound Waves ◽  
Detached Eddy Simulation ◽  
Airframe Noise ◽  
Interference Phenomenon ◽  
Delayed Detached Eddy Simulation ◽  
The Doors

The aerodynamic noise of landing gears have been widely studied as an important component of the airframe noise. During take-off and landing, there are doors, cavity and fuselage around the landing gear. The noise caused by these aircraft components will interfere with aerodynamic noise generated by the landing gear itself. Hence, paper proposes an Improved Delayed Detached Eddy Simulation (IDDES) method for the investigation of the flow field around a single fuselage nose landing gear (NLG) model and a fuselage nose landing gear model with doors, cavity and fuselage nose (NLG-DCN) respectively. The difference between the two flow fields were analyzed in detail to better understand the influence of these components around the aircraft’s landing gear, and it was found that there is a serious mixing phenomenon among the separated flow from the front doors, the unstable shear layer falling off the leading edge of the cavity and the wake of the main strut which directly leads to the enhancement of the noise levels. Furthermore, after the noise sound waves are reflected by the doors several times, an interference phenomenon is generated between the doors. This interference may be a reason why the tone excited in the cavity is suppressed.

Near-Field Noise Prediction for Landing Gear Based on Detached Eddy Simulations

2014 ◽  
Vol 472 ◽  
pp. 105-110
Author(s):  
Ning Hu ◽  
Xuan Hao ◽  
Cheng Su ◽  
Wei Min Zhang ◽  
Han Dong Ma
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Sound Pressure ◽  
Near Field ◽  
Separated Flow ◽  
Landing Gear ◽  
Aerodynamic Noise ◽  
Noise Prediction ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

A four-wheel rudimentary landing gear is studied numerically by detached eddy simulation (DES) based on the Spalart-Allmaras turbulence model. The surface sound pressure level and sound pressure spectra are calculated using the obtained unsteady flow field. The investigation shows that DES can describe the steady and unsteady properties in the flow around rudimentary landing gear. It can give reasonable results since the flow around the landing gear is a massive separated flow. The results prove the feasibility of DES type methods in massive separated unsteady flow field and aerodynamic noise prediction for landing gear, and can be used in the study of landing gear noise reduction.

Detached-Eddy Simulations Over a Simplified Landing Gear

2002 ◽  
Vol 124 (2) ◽  
pp. 413-423 ◽  
Author(s):  
L. S. Hedges ◽  
A. K. Travin ◽  
P. R. Spalart
Keyword(s):  
Stokes Equations ◽  
Separated Flow ◽  
Flow Fields ◽  
Equation Model ◽  
Landing Gear ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Navier Stokes Equations ◽  
Instantaneous Flow ◽  
Eddy Simulation

The flow around a generic airliner landing-gear truck is calculated using the methods of Detached-Eddy Simulation, and of Unsteady Reynolds-Averaged Navier-Stokes Equations, with the Spalart-Allmaras one-equation model. The two simulations have identical numerics, using a multi-block structured grid with about 2.5 million points. The Reynolds number is 6×105. Comparison to the experiment of Lazos shows that the simulations predict the pressure on the wheels accurately for such a massively separated flow with strong interference. DES performs somewhat better than URANS. Drag and lift are not predicted as well. The time-averaged and instantaneous flow fields are studied, particularly to determine their suitability for the physics-based prediction of noise. The two time-averaged flow fields are similar, though the DES shows more turbulence intensity overall. The instantaneous flow fields are very dissimilar. DES develops a much wider range of unsteady scales of motion and appears promising for noise prediction, up to some frequency limit.

Simulation of Dynamic Stall on an Elastic Rotor in High-Speed Turn Flight

2020 ◽  
Vol 65 (2) ◽  
pp. 1-12
Author(s):  
Johannes Letzgus ◽  
Manuel Keßler ◽  
Ewald Krämer
Keyword(s):  
High Speed ◽  
Separated Flow ◽  
Flight Test ◽  
Dynamic Stall ◽  
Minor Role ◽  
Detached Eddy Simulation ◽  
Rotor Aerodynamics ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
A Minor

A highly loaded, high-speed turn flight of Airbus Helicopters' Bluecopter demonstrator helicopter is simulated to investigate dynamic stall using a loose computational fluid dynamics/structural dynamics (CFD/CSD) coupling of the flow solver FLOWer and the rotorcraft comprehensive code CAMRAD II. The rotor aerodynamics is computed using a high-fidelity delayed detached-eddy simulation (DDES). A three-degree-of-freedom trim of an isolated rotor is performed, yielding main-rotor control angles that agree well with the flight-test measurements. The flow field in this flight condition is found to be highly unsteady and complex, featuring massively separated flow, blade–vortex interaction, multiple dynamic-stall events, and shock-induced separation. The computed pitch-link loads are compared to flight-test measurements. This shows that all CFD/CSD cases underpredict the amplitudes of the flight test and yield phase shifts. However, overall trends agree reasonably. Also, varying the computational setup reveals that the shear stress transport–DDES turbulence model performs better than Spalart–Allmaras–DDES, that the consideration of the rotor hub and fuselage improves the agreement with flight-test data, and that the elastic twist plays only a minor role in the dynamic-stall events.

Prediction of Aeroacoustic and Control over a Cavity by Delayed Detached Eddy Simulation

2014 ◽  
Vol 598 ◽  
pp. 505-509 ◽  
Author(s):  
Yu Liu ◽  
Ming Bo Tong
Keyword(s):  
Sound Pressure ◽  
Noise Suppression ◽  
Cfd Simulation ◽  
Leading Edge ◽  
Pressure Level ◽  
Detached Eddy Simulation ◽  
Suppression Effect ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
And Control

In the present study CFD simulation with delayed detached eddy simulation (DDES) are performed to investigate an open cavity at Mach 0.85. Two cavity configurations, clean cavity and cavity with a leading-edge saw tooth spoiler, are modeled. The results obtained from clean cavity prediction are compared with experimental sound pressure level (SPL) data from QinetiQ, UK. Furthermore, comparisons are made with the predicted SPL between the two configurations. The main focuses of this investigation are to obtain a further understanding of the cavity aeroacoustics and test the noise suppression effect by a saw tooth spoiler.

Detached Eddy Simulation of Transition in Turbomachinery: Linear Compressor Cascade

2021 ◽  
pp. 1-10
Author(s):  
Zifei Yin ◽  
Paul Durbin
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Separated Flow ◽  
Adaptive Model ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Linear Compressor Cascade

Abstract The adaptive, l2-omega delayed detached eddy simulation model was selected to simulate the flow in the V103 linear compressor cascade. The Reynolds number based on axial chord length is 138,500. Varies inflow turbulent intensities from 0% to 10% were tested to evaluate the performance of the adaptive model. The adaptive model is capable of capturing the laminar boundary layer and the large scale perturbations inside it. The instability of large scale disturbances signals the switch to a hybrid simulation of turbulent boundary layer -- the transition front is thus predicted. In the case of separation-induced transition, the adaptive model, which uses eddy simulation in separated flow, can predict the separation bubble size accurately. Generally, the adaptive, delayed detached eddy simulation model can simulate the transitional separated flow in a linear compressor cascade, with a correct response to varying turbulent intensities.

Numerical Study of Flow Physics Behind the Aerodynamic Performance on an Airfoil With Leading Edge Tubercles

2016 ◽  
Author(s):  
Mingming Zhang ◽  
Ming Zhao ◽  
Jianzhong Xu
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Physical Models ◽  
Vortical Flow ◽  
Detached Eddy Simulation ◽  
Flow Physics ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Solid Foundation

This paper presents a numerical analysis of the flow physics behind the effects of leading-edge protuberances on airfoil performances at low Reynolds number with an aim to provide a solid foundation for the engineering applications in the near future. An improved delayed detached eddy simulation (IDDES) method based on a transition model was proposed and validated through comparisons with experimental results. Utilizing the IDDES scheme, together with vortex dynamic method, investigations were focused on the stall and post-stall regions, respectively. It was found that an interesting ‘bi-periodic’ phenomenon within stall region, i.e. converged and diverged vortical flow in adjacent trough sections of tubercles, was created with the complicated evolution of the generated streamwise counter-rotating vortex pairs, resulting in the degraded aerodynamic characteristics as well as rather gentle stall process. For the post-stall cases, the impaired flow detachment around both peak and trough sections of tubercles were responsible for the improved airfoil performance. In addition, two physical models within the two regions were also built to further clarify the flow physics in a general way.

scholarly journals Investigation and Improvement of Stall Characteristic of High-Lift Configuration without Slats

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Zhao Yang ◽  
Jie Li ◽  
Jing Jin ◽  
Heng Zhang ◽  
Youxu Jiang
Keyword(s):  
Evaluation Method ◽  
Leading Edge ◽  
Suction Side ◽  
Aerodynamic Characteristics ◽  
Angle Distribution ◽  
Detached Eddy Simulation ◽  
High Lift ◽  
Eddy Simulation ◽  
Business Jet ◽  
Delayed Detached Eddy Simulation

In order to simplify the manufacturing process or because of the limitation of the propulsion system, business jet, small civil airplane, and turboprop aircraft are always designed without leading-edge slats, which poses a great challenge to the flight safety during takeoff and landing. Focusing on the low-speed stall and poststall conditions, we investigated the aerodynamic characteristics and flow mechanism of high-lift configuration without slats using an improved delayed detached eddy simulation (IDDES) model which is validated by numerical simulations of the Common Research Model (CRM). Based on the analysis of the calculated results, conclusion can be made that the stall behavior of the configurations is directly related to the onset and evaluation of flow separation on the suction side. And through further research, an efficient evaluation method that is capable of qualitatively predicting the stall performance of two-element high-lift configuration by stall angle distribution of wing sections is proposed. By using the evaluation method, together with design rules summarized from the present study, high-lift configuration with mild-stall characteristic can be obtained in the preliminary stage of design.

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