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.

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.

Numerical Investigation of Intermittent Corner Separation in a Linear Compressor Cascade

2016 ◽  
Author(s):  
Wei Ma ◽  
Feng Gao ◽  
Xavier Ottavy ◽  
Lipeng Lu ◽  
A. J. Wang
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Leading Edge ◽  
Suction Side ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Corner Separation ◽  
Eddy Simulation ◽  
Linear Compressor Cascade

Recently bimodal phenomenon in corner separation has been found by Ma et al. (Experiments in Fluids, 2013, doi:10.1007/s00348-013-1546-y). Through detailed and accurate experimental results of the velocity flow field in a linear compressor cascade, they discovered two aperiodic modes exist in the corner separation of the compressor cascade. This phenomenon reflects the flow in corner separation is high intermittent, and large-scale coherent structures corresponding to two modes exist in the flow field of corner separation. However the generation mechanism of the bimodal phenomenon in corner separation is still unclear and thus needs to be studied further. In order to obtain instantaneous flow field with different unsteadiness and thus to analyse the mechanisms of bimodal phenomenon in corner separation, in this paper detached-eddy simulation (DES) is used to simulate the flow field in the linear compressor cascade where bimodal phenomenon has been found in previous experiment. DES in this paper successfully captures the bimodal phenomenon in the linear compressor cascade found in experiment, including the locations of bimodal points and the development of bimodal points along a line that normal to the blade suction side. We infer that the bimodal phenomenon in the corner separation is induced by the strong interaction between the following two facts. The first is the unsteady upstream flow nearby the leading edge whose angle and magnitude fluctuate simultaneously and significantly. The second is the high unsteady separation in the corner region.

Improved Delayed Detached Eddy Simulation (IDDES) of a 1.5 Stage Axial Compressor Non-Synchronous Vibration

2020 ◽  
Author(s):  
Purvic Patel ◽  
Yunchao Yang ◽  
Gecheng Zha
Keyword(s):  
Rotor Blade ◽  
High Speed ◽  
Stokes Equations ◽  
Axial Compressor ◽  
Suction Side ◽  
Tip Vortex ◽  
Weno Scheme ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

Abstract This paper utilizes the Improved Delayed Detached Eddy Simulation (IDDES) to investigate the non-synchronous vibration (NSV) mechanism of a 1.5 stage high-speed axial compressor. The NSV occurs at a part speed in the rig test. A low diffusion E-CUSP approximate Riemann solver with a third order Weighted Essentially Non-Oscillating (WENO) scheme for the inviscid flux and a second order central differencing scheme for the viscous flux are employed to solve the 3D time accurate Navier-Stokes equations. The fully conservative sliding boundary condition is used to preserve the wake-propagation. The aerodynamic instability in the tip region induces two alternating low pressure regions near the leading and the trailing edge on the suction side of the rotor blade. It is observed that the circumferential tip vortex motion in the rotor passage above 75 % span and its coupling forces cause NSV at the operating speed. This instability moves in the counter-rotating direction in the rotational frame. The NSV results using URANS simulation is also presented for comparison. The predicted frequency with the IDDES and URANS using rigid blades agrees well with the measured frequency in the rig test. In addition to the NSV, the IDDES solver also captures the dominant engine order frequencies. The tip flow structures show the vortex filament with one end on the suction side of the rotor blade and other side terminating on the casing or the pressure side of the rotor blade.

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.

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