The influence of unsteady perturbations on the flow in a forward separation region upstream of a cone

1996 ◽  
Vol 31 (2) ◽  
pp. 274-283 ◽  
Author(s):  
V. S. Khlebnikov
Keyword(s):  
Separation Region ◽  
Forward Separation

scholarly journals Effect of the Reynolds Number and Clearance Flow on the Aerodynamic Characteristics of a New Variable Inlet Guide Vane

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 172
Author(s):  
Hengtao Shi
Keyword(s):  
Reynolds Number ◽  
Guide Vane ◽  
Three Dimensional ◽  
High Growth ◽  
Aerodynamic Characteristics ◽  
Inlet Guide Vane ◽  
Separation Region ◽  
Clearance Flow ◽  
New Type ◽  
Variable Inlet Guide Vane

Recently, a new type of low-loss variable inlet guide vane (VIGV) was proposed for improving a compressor’s performance under off-design conditions. To provide more information for applications, this work investigated the effect of the Reynolds number and clearance flow on the aerodynamic characteristics of this new type of VIGV. The performance and flow field of two representative airfoils with different chord Reynolds numbers were studied with the widely used commercial software ANSYS CFX after validation was completed. Calculations indicate that, with the decrease in the Reynolds number Rec, the airfoil loss coefficient ω and deviation δ first increase slightly and then entered a high growth rate in a low range of Rec. Afterwards, a detailed boundary-layer analysis was conducted to reveal the flow mechanism for the airfoil performance degradation with a low Reynolds number. For the design point, it is the appearance and extension of the separation region on the rear portion; for the maximum incidence point, it is the increase in the length and height of the separation region on the former portion. The three-dimensional VIGV research confirms the Reynolds number effect on airfoils. Furthermore, the clearance leakage flow forms a strong stream-wise vortex by injection into the mainflow, resulting in a high total-pressure loss and under-turning in the endwall region, which shows the potential benefits of seal treatment.

Effect of a conical separation region on cold gas-dynamic spraying

2012 ◽  
Vol 53 (6) ◽  
pp. 948-953 ◽  
Author(s):  
A. P. Alkhimov ◽  
V. F. Kosarev ◽  
S. V. Klinkov ◽  
A. A. Sova
Keyword(s):  
Cold Gas Dynamic Spraying ◽  
Separation Region ◽  
Gas Dynamic ◽  
Cold Gas

scholarly journals RANS and LES analysis of a separation region in front of a backward-facing step

2018 ◽  
Vol 980 ◽  
pp. 012026
Author(s):  
T A Baranova ◽  
V L Zhdanov ◽  
D A Ivanov ◽  
Ja I Smulsky ◽  
V I Terekhov
Keyword(s):  
Separation Region ◽  
Backward Facing Step

Part II: Steady aerofoil-spoiler characteristics

1987 ◽  
Vol 91 (908) ◽  
pp. 359-366
Keyword(s):  
Separated Flow ◽  
Experimental Results ◽  
Surface Singularity ◽  
Separation Region ◽  
Two Dimensional ◽  
Trailing Edge ◽  
Singularity Method ◽  
Total Head ◽  
Low Speeds ◽  
Theoretical Results

Summary A surface singularity method has been formulated to predict two-dimensional spoiler characteristics at low speeds. Vorticity singularities are placed on the aerofoil surface, on the spoiler surface, on the upper separation streamline from the spoiler tip and on the lower separation streamline from the aerofoil trailing edge. The separation region is closed downstream by two discrete vortices. The flow inside the separation region is assumed to have uniform total head. The downstream extent of the separated wake is an empirical input. The flows both external and internal to the separated regions are solved. Theoretical results have been obtained for a range of spoiler-aerofoil configurations which compare reasonably with experimental results. The model is deficient in that it predicts a higher compression ahead of the spoiler than obtained in practice. Furthermore, there is a minimum spoiler angle below which a solution is not possible; it is thought that this feature is related to the physical observation that at small spoiler angles, the separated flow from the spoiler reattaches on the aerofoil upper surface ahead of the trailing edge.

Specific heat of the liquid mixtures of neon and hydrogen isotopes in the phase-separation region

Physica ◽  
1970 ◽  
Vol 50 (1) ◽  
pp. 93-124 ◽  
Author(s):  
J.P. Brouwer ◽  
C.J.N. Van Den Meijdenberg ◽  
J.J.M. Beenakker
Keyword(s):  
Phase Separation ◽  
Specific Heat ◽  
Hydrogen Isotopes ◽  
Liquid Mixtures ◽  
Separation Region ◽  
Phase Separation Region

scholarly journals Flow modulation by a mushroom-like coating around the separation region of a wind-turbine airfoil section

2018 ◽  
Vol 10 (4) ◽  
pp. 043305 ◽  
Author(s):  
Ali Doosttalab ◽  
Suranga Dharmarathne ◽  
Humberto Bocanegra Evans ◽  
Ali M. Hamed ◽  
Serdar Gorumlu ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Separation Region ◽  
Flow Modulation ◽  
Airfoil Section ◽  
Wind Turbine Airfoil

scholarly journals Impact Anlysis of Bow Flap on LHA-1 Ship Airwake

2018 ◽  
Vol 179 ◽  
pp. 03007
Author(s):  
Jinling Wang ◽  
Guangwen Jiang ◽  
Jun Shen ◽  
Chujun Hu
Keyword(s):  
Numerical Simulation ◽  
Simulation Method ◽  
Equation Model ◽  
Separation Region ◽  
Operating Environment ◽  
Study Results ◽  
Helicopter Landing ◽  
Hybrid Grid ◽  
Under Construction ◽  
The Impact

The sharp 90°corner of bow found on American Tarawa class general amphibious assault ship LHA-1 will produce large separated region in the airwake over the ship, and the turbulence in the separation region seriously affects the operation safety of the helicopter. In order to reduce the separation in bow region of the LHA-1, and optimize the helicopter operating environment, the numerical simulation method is used to study the influence of the bow flap on the airwake of LHA-1. The study results show that: the ANSYS k-ε two equation model based on the hybrid grid can be used to predict the steady-state characteristics of the ship airwake; the bow flap can improve the flow field downwind of the flap installation position, and the impact range can cover two spots; in headwind, the optimal installation angle of the bow flap is 15°~25°. The research results of this paper can provide modification and improvement reference for the amphibious assault ship in-service and under construction, so as to achieve the purpose of optimizing the ship airwake, thereby improving the safety of helicopter landing process and extending the service life.

scholarly journals Investigation of Vortical Structures and Turbulence Characteristics in Corner Separation in an Axial Compressor Stator Using DDES

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2123
Author(s):  
Jun Li ◽  
Jun Hu ◽  
Chenkai Zhang
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Suction Side ◽  
Turbulence Energy ◽  
Separation Flow ◽  
Mechanism Analysis ◽  
Separation Region ◽  
Detached Eddy Simulation ◽  
Vortical Structures ◽  
Corner Separation

In order to investigate the flow structure and unsteady behavior of three-dimensional corner separation, a delayed detached-eddy simulation (DDES) method based on the Spalart–Allmaras (SA) model is performed on the third-stage stator of a multistage low-speed axial compressor. The stator simulation is validated by experiments before flow mechanism analysis. The complicated flow fields in the stator are then described step by step. Firstly, the structure and development process of vortices in corner separation flow are analyzed. Secondly, the velocity histogram of the monitor points in the mainstream and corner separation regions is obtained, and the velocity distribution of the corner separation region is discussed. Finally, Reynolds stress, Lumley anisotropy, turbulence energy spectra, and helicity density are discussed to understand the turbulence behavior of the corner separation flow in the stator. The results show that the corner separation appears at even the design condition and different kinds of vortical structures appear in the stator hub corner. The unsteadiness of corner separation flow is mainly reflected in the separation on the suction side of the blade and the wake shedding. Turbulence anisotropy and energy backscatter are found to be dominant in the separation region, which is correlated to the high shear stress.

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