scholarly journals Turbulent Triggers and the Model Quality Influence on Aerodynamic Characteristics of the Laminar Aerofoil in Transonic Flow Regime

2019 ◽  
Vol 26 (3) ◽  
pp. 165-172
Author(s):  
Robert Placek ◽  
Paweł Ruchała
Keyword(s):  
Aerodynamic Characteristic ◽  
Aerodynamic Characteristics ◽  
Boundary Layer Transition ◽  
Model Surface ◽  
Model Quality ◽  
Layer Transition ◽  
Beneficial Effects ◽  
Shock Position ◽  
Current Article

Abstract The test with a roughness application on the laminar aerofoil has been conducted in the N-3 trisonic wind tunnel of the Institute of Aviation in Warsaw. The main goal of tests was to investigate the influence of the boundary layer transition triggers on a laminar profile aerodynamic characteristic. For baseline configuration, the natural transition was applied. As a local roughness on the upper model surface, the carborundum strips with different heights were applied. These were positioned on the upper model surface in the front of the shock position occurrence. The Mach number during test was equal Ma = 0.7 and Reynolds number was about 2.85·106. Tests have been conducted for different model incidence in range 0°-7°. Current article refers partially to the previous study, where aerofoil model with lower quality of surface had been tested. Investigation results from previous work indicated that some of transition positions improved an aerodynamic characteristic by reducing the drag coefficient value and decreasing shock wave unsteadiness in the transonic regime. However, current article indicates that beneficial effects in respect to the baseline configuration are also strictly dependent on the model quality and turbulent triggers size. Improved surface quality of the laminar aerofoil model affected on aerodynamic characteristics with and without turbulent triggers. Resultant aerodynamic coefficients of all tested cases i.e. drag, lift and lift to drag ratio were compared.

Aerodynamic characteristics of cones at small angles of attack in the presence of boundary layer transition

1991 ◽  
Vol 26 (1) ◽  
pp. 139-144
Author(s):  
V. N. Andreev ◽  
V. A. Kozlovskii ◽  
K. A. Stekenius
Keyword(s):  
Boundary Layer ◽  
Aerodynamic Characteristics ◽  
Boundary Layer Transition ◽  
Layer Transition

The Potential of Rotor and Stator Clocking in a 2.5-Stage Low-Speed Axial Compressor

2012 ◽  
Author(s):  
J. Städing ◽  
J. Friedrichs ◽  
T. Waitz ◽  
C. Dobriloff ◽  
B. Becker ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Axial Flow ◽  
Pressure Rise ◽  
Boundary Layer Transition ◽  
Experimental Investigations ◽  
Layer Transition ◽  
Low Speed ◽  
Beneficial Effects ◽  
Pass Through ◽  
Flow Compressor

Detailed experimental investigations have been conducted to gain profound knowledge of airfoil clocking mechanisms in axial compressors. Clocking, the circumferential indexing of adjacent rotor or stator rows with equal blade counts, is known as a potential means to modify the flow field in multistage turbo-machinery and increase overall efficiencies of both turbines and compressors. These beneficial effects on turbomachine performance are due to wake-airfoil interactions and primarily depend on the alignment of a downstream blade or vane row with upstream wake trajectories that are generated in the same frame of reference. The present survey describes and discusses the experimental research on Rotor and Stator Clocking effects in a low-speed 2.5-stage axial flow compressor. For both Rotor and Stator Clocking, variations of Stage 2 performance have been found that are sinusoidal in trend over the clocking angle and originate from a significant change in static pressure rise across the clocked blade rows. Time-averaged measurements basically suggest the highest pressure gain, if the upstream wakes pass through mid-passage of the downstream blade row. In case of Rotor Clocking, this may even lead to a variation in compressor operating range. The fundamental aerodynamic mechanism responsible for the clocking effect can be attributed to a shift of the suction-sided boundary layer transition over the clocking angle. Regarding overall Stage 2 performance, the investigations show that Full Clocking, i.e. the combination of Rotor and Stator Clocking, nearly doubles the potential of single row indexing.

scholarly journals On the Effects of an Installed Propeller Slipstream on Wing Aerodynamic Characteristics

10.14311/562 ◽  
2004 ◽  
Vol 44 (3) ◽  
Author(s):  
F. M. Catalano
Keyword(s):  
Boundary Layer ◽  
Relative Position ◽  
Aerodynamic Characteristics ◽  
Boundary Layer Transition ◽  
Flow Visualisation ◽  
Two Dimensional ◽  
Wind Tunnel Experiments ◽  
Layer Transition ◽  
Laminar Separation ◽  
Turbulent Separation

This work presents an experimental study of the effect of an installed propeller slipstream on a wing boundary layer. The main objective was to analyse through wind tunnel experiments the effect of the propeller slipstream on the wing boundary layer characteristics such as: laminar flow extension and transition, laminar separation bubbles and reattachment and turbulent separation. Two propeller/wing configurations were studied: pusher and tractor. Experimental work was performed using two different models: a two-dimensional wing with a central cylindrical nacelle for the tractor configuration, and a simple two-dimensional wing with a downstream propeller for the pusher tests. The relative position between propeller and wing could be changed in the pusher model, and a total of 7 positions were analysed. For the tractor tests the relative propeller/wing was fixed, but three different propellers: two, three and four bladed were tested. Measurements included pressure distribution, hot wire anemometry and boundary layer characteristics by flow visualisation. The results showed that the pusher propeller inflow affects the wing characteristics by changing the lift, drag, and also delays the boundary layer transition and separation. These effects are highly dependent on the relative position of the wing/propeller. On the other hand, the tractor propeller slipstream induces transition and its effect is dependent on the number of blades.

scholarly journals Experimental and Computational Study of Archery Arrows Fletched with Straight Vanes

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 56
Author(s):  
Julio Ortiz ◽  
Atsushi Serino ◽  
Toshinari Hasegawa ◽  
Takahito Onoguchi ◽  
Hiroki Maemukai ◽  
...  
Keyword(s):  
Initial Velocity ◽  
Computational Study ◽  
Aerodynamic Characteristics ◽  
Magnetic Suspension ◽  
Boundary Layer Transition ◽  
Free Flight ◽  
Layer Transition ◽  
Experimental Procedure ◽  
Balance System ◽  
Velocity Decay

The aerodynamic characteristics of archery arrows fletched with two types of straight vanes, for which the area is different, were studied. The arrows’ pitching moment (CM), lift (CL) and drag (CD) coefficients were measured in the 60 × 60 cm Magnetic Suspension and Balance System (MSBS) from JAXA. At a Reynolds number of Re = 1.2 × 104, the values of CD were 1.56 and 2.05 for the short and large vanes, respectively. In a second experimental procedure, the arrows’ deceleration in free flight was measured by inserting an acceleration sensor inside their shafts. For shots with an initial velocity of around 56.4 ms−1, a velocity decay of around 8% was measured. A turbulent–laminar boundary layer transition during free flight was found for shots with an average Re = 1.8 × 104. Lastly, through numerical computations, the area difference of the two vanes was analyzed to verify the importance of CM and CL during the arrows’ flights.

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF BOUNDARY LAYER TRANSITION ON BLUNTED CONES AT SUPERSONIC FLOW

2010 ◽  
Vol 40 (3) ◽  
pp. 309-319 ◽  
Author(s):  
V. N. Brazhko ◽  
A. V. Vaganov ◽  
N. A. Kovaleva ◽  
N. P. Kolina ◽  
I. I. Lipatov
Keyword(s):  
Boundary Layer ◽  
Supersonic Flow ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Numerical Investigations
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