Aerodynamic and Aeroacoustic Performance of Tail Rotor Investigation and Modification

Eddy Simulation ◽

Basic Model ◽

Rotor Design ◽

Sound Simulation ◽

Total Thrust

With the increasingly stringent airworthiness standards, the noise generated during the rotorcraft flight is gradually attracting people’s attention. It widely operated helicopters at low altitudes because of their maneuverability. The way to reduce the noise caused by the complex airflow of the helicopter rotor system has progressively become a hot topic for researchers. Using a hybrid acoustic analysis method, this paper investigates the improvement of the noise and thrust of the helicopter’s tail rotor through the tail rotor structural parameters. For the basic model, the turbulence simulation is performed using an incompressible detached eddy simulation (DES) method, and the Lighthill acoustic analog equation is calculated using the finite element method (FEM). We verified the accuracy of the method through wind tunnel tests. We chose a series of structural parameters for sound simulation and fluid simulation calculations. The results indicate that the modified tail rotor noise reduced by 16.5 dBA and the total thrust increased by 19.9% from the prototype model. This work can enhance the duct tail rotor design to improve aerodynamic and aeroacoustic performance.

Aerodynamic and acoustic analysis of an extruded airfoil with a trailing edge device using Detached Eddy Simulation with a Discontinuous Galerkin method

10.2514/6.2013-2429 ◽

2013 ◽

Cited By ~ 3

Author(s):

Michael Wurst ◽

Manuel Kessler ◽

Ewald Kraemer

Keyword(s):

Galerkin Method ◽

Discontinuous Galerkin ◽

Discontinuous Galerkin Method ◽

Acoustic Analysis ◽

Trailing Edge ◽

Eddy Simulation

High-Order Delayed Detached Eddy Simulation of Separated Flow with Self-Adaptive Dissipation

Journal of Aircraft ◽

10.2514/1.c036017 ◽

2020 ◽

pp. 1-12

Author(s):

Li Hao ◽

Liu Wei ◽

Wang Shengye ◽

Wang Guangxue

Keyword(s):

Separated Flow ◽

High Order ◽

Eddy Simulation ◽

Self Adaptive

Improved Delayed Detached Eddy Simulation of AGARD Wing Flutter with Fully Coupled Fluid-Structure Interaction

AIAA Scitech 2021 Forum ◽

10.2514/6.2021-0365 ◽

2021 ◽

Author(s):

Purvic Patel ◽

Gecheng Zha

Keyword(s):

Fluid Structure Interaction ◽

Fluid Structure ◽

Structure Interaction ◽

Wing Flutter ◽

Eddy Simulation ◽

Fully Coupled

A new formulation for delayed detached eddy simulation based on the Smagorinsky LES model

10.31274/etd-180810-4055 ◽

2015 ◽

Author(s):

Karthik Rudra Reddy

Keyword(s):

Eddy Simulation ◽

Simulation Based ◽

New Formulation ◽

Les Model

Assessing IDDES-Based Wall-Modeled Large-Eddy Simulation (WMLES) for Separated Flows with Heat Transfer

Fluids ◽

10.3390/fluids6070246 ◽

2021 ◽

Vol 6 (7) ◽

pp. 246

Author(s):

Rozie Zangeneh

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Large Eddy Simulation ◽

Skin Friction ◽

Heat Fluxes ◽

Separated Flows ◽

Eddy Simulation ◽

Large Eddy ◽

Isothermal Wall

The Wall-modeled Large-eddy Simulation (WMLES) methods are commonly accompanied with an underprediction of the skin friction and a deviation of the velocity profile. The widely-used Improved Delayed Detached Eddy Simulation (IDDES) method is suggested to improve the prediction of the mean skin friction when it acts as WMLES, as claimed by the original authors. However, the model tested only on flow configurations with no heat transfer. This study takes a systematic approach to assess the performance of the IDDES model for separated flows with heat transfer. Separated flows on an isothermal wall and walls with mild and intense heat fluxes are considered. For the case of the wall with heat flux, the skin friction and Stanton number are underpredicted by the IDDES model however, the underprediction is less significant for the isothermal wall case. The simulations of the cases with intense wall heat transfer reveal an interesting dependence on the heat flux level supplied; as the heat flux increases, the IDDES model declines to predict the accurate skin friction.

Numerical study of flow and noise predictions for tandem cylinders using incompressible improved delayed detached eddy simulation combined with acoustic perturbation equations

Ocean Engineering ◽

10.1016/j.oceaneng.2021.108740 ◽

2021 ◽

Vol 224 ◽

pp. 108740

Author(s):

Guang Chen ◽

Xi-Feng Liang ◽

Dan Zhou ◽

Xiao-Bai Li ◽

Fu-sang Lien

Keyword(s):

Numerical Study ◽

Acoustic Perturbation ◽

Eddy Simulation ◽

Tandem Cylinders ◽

Perturbation Equations

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

Numerical study of the flow over the modified simple frigate shape

10.1177/0954410020977752 ◽

2020 ◽

pp. 095441002097775

Author(s):

Tong Li ◽

Yibin Wang ◽

Ning Zhao

Keyword(s):

Bluff Body ◽

Recirculation Zone ◽

Numerical Study ◽

Reference Value ◽

Flow Fields ◽

Navier Stokes ◽

Eddy Simulation ◽

Simulation Results

The simple frigate shape (SFS) as defined by The Technical Co-operative Program (TTCP), is a simplified model of the frigate, which helps to investigate the basic flow fields of a frigate. In this paper, the flow fields of the different modified SFS models, consisting of a bluff body superstructure and the deck, were numerically studied. A parametric study was conducted by varying both the superstructure length L and width B to investigate the recirculation zone behind the hangar. The size and the position of the recirculation zones were compared between different models. The numerical simulation results show that the size and the location of the recirculation zone are significantly affected by the superstructure length and width. The results obtained by Reynolds-averaged Navier-Stokes method were also compared well with both the time averaged Improved Delayed Detached-Eddy Simulation results and the experimental data. In addition, by varying the model size and inflow velocity, various flow fields were numerically studied, which indicated that the changing of Reynolds number has tiny effect on the variation of the dimensionless size of the recirculation zone. The results in this study have certain reference value for the design of the frigate superstructure.

Numerical Investigation on the Influence of the Streamlined Structures of the High-Speed Train’s Nose on Aerodynamic Performances

Applied Sciences ◽

10.3390/app11020784 ◽

2021 ◽

Vol 11 (2) ◽

pp. 784

Author(s):

Zhenxu Sun ◽

Shuanbao Yao ◽

Lianyi Wei ◽

Yongfang Yao ◽

Guowei Yang

Keyword(s):

Drag Reduction ◽

Pressure Distribution ◽

Flow Separation ◽

High Speed ◽

Leeward Side ◽

Side Force ◽

Eddy Simulation ◽

Asymmetrical Design

The structural design of the streamlined shape is the basis for high-speed train aerodynamic design. With use of the delayed detached-eddy simulation (DDES) method, the influence of four different structural types of the streamlined shape on aerodynamic performance and flow mechanism was investigated. These four designs were chosen elaborately, including a double-arch ellipsoid shape, a single-arch ellipsoid shape, a spindle shape with a front cowcatcher and a double-arch wide-flat shape. Two different running scenes, trains running in the open air or in crosswind conditions, were considered. Results reveal that when dealing with drag reduction of the whole train running in the open air, it needs to take into account how air resistance is distributed on both noses and then deal with them both rather than adjust only the head or the tail. An asymmetrical design is feasible with the head being a single-arch ellipsoid and the tail being a spindle with a front cowcatcher to achieve the minimum drag reduction. The single-arch ellipsoid design on both noses could aid in moderating the transverse amplitude of the side force on the tail resulting from the asymmetrical vortex structures in the flow field behind the tail. When crosswind is considered, the pressure distribution on the train surface becomes more disturbed, resulting in the increase of the side force and lift. The current study reveals that the double-arch wide-flat streamlined design helps to alleviate the side force and lift on both noses. The magnitude of side force on the head is 10 times as large as that on the tail while the lift on the head is slightly above that on the tail. Change of positions where flow separation takes place on the streamlined part is the main cause that leads to the opposite behaviors of pressure distribution on the head and on the tail. Under the influence of the ambient wind, flow separation occurs about distinct positions on the train surface and intricate vortices are generated at the leeward side, which add to the aerodynamic loads on the train in crosswind conditions. These results could help gain insight on choosing a most suitable streamlined shape under specific running conditions and acquiring a universal optimum nose shape as well.