Combined Numerical and Experimental Study on the Use of Gurney Flaps for the Performance Enhancement of NACA0021 Airfoil in Static and Dynamic Conditions

2021 ◽  
Author(s):  
Francesco Balduzzi ◽  
David Holst ◽  
Pier Francesco Melani ◽  
Felix Wegner ◽  
Christian Navid Nayeri ◽  
...  
Keyword(s):  
Experimental Study ◽  
Performance Enhancement ◽  
Dynamic Conditions ◽  
Gurney Flaps

Combined Numerical and Experimental Study on the Use of Gurney Flaps for the Performance Enhancement of NACA0021 Airfoil in Static and Dynamic Conditions

2020 ◽  
Author(s):  
Francesco Balduzzi ◽  
David Holst ◽  
Pier Francesco Melani ◽  
Felix Wegner ◽  
Christian Navid Nayeri ◽  
...  
Keyword(s):  
Wind Energy ◽  
Performance Enhancement ◽  
Vertical Axis ◽  
Hysteresis Cycle ◽  
Dynamic Conditions ◽  
Energy Applications ◽  
Gurney Flaps ◽  
Industrial Community ◽  
Sinusoidal Motion ◽  
The Impact

Abstract Power augmentation devices in wind energy applications have been receiving increasing interest from both the scientific and the industrial community. In particular, Gurney Flaps (GFs) showed a great potential thanks to the passive functioning, the simple construction and the possibility to add them as a retrofit to existing rotors. Within this context, the authors have performed an extended investigation on the lift increase capabilities of GFs for the well-known NACA 0021 airfoil, which has been used in several wind energy applications up to now. The present paper shows the results of a combined experimental and numerical analysis considering different geometrical configurations of the flaps under both static and dynamic conditions. Experimental data were first obtained for the AoA range of 180 degrees at a Reynolds number of 180 k to analyze the impact of three different geometrical configurations of the GF on the aerodynamic behavior. The geometrical configurations were defined by varying the length of the flap (1.4% and 2.5% of the chord) and its inclination angle with respect to the blade chord (90 degrees and 45 degrees). The experimental investigation involved also dynamic sinusoidal pitching movements at multiple reduced frequencies to evaluate the stall hysteresis cycle. An unsteady CFD numerical model was calibrated against wind tunnel data and then exploited to extend the investigation to a wider range of Reynolds numbers for dynamic AoA rates of change typical of vertical-axis wind turbines, i.e. characterized by higher reduced frequencies with a non-sinusoidal motion law.

Performance Enhancement of Recycled Aggregate Concrete – An Experimental Study

2021 ◽  
Author(s):  
Sivamani Jagan ◽  
Thurvas Renganathan Neelakantan ◽  
Palaniraj Saravanakumar
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Elastic Modulus ◽  
Performance Enhancement ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Durability Properties ◽  
Concrete Mixtures

Extensive studies have been performed on the mechanical and durability properties of the concrete prepared with recycled coarse aggregates (RCA), however, only modest consideration has been given to the studies on the behaviour of RAC prepared by alternative mixing approach techniques. This study presents the mechanical properties of the recycled aggregate concrete (RAC) with different percentages of RCA prepared by normal mixing approach (NMA), two-stage mixing approach (TSMA) and sand enveloped mixing approach (SEMA) techniques. The manufactured concrete mixtures were tested for compression, tension, flexure and elastic modulus at 7, 28 and 90 days. The results indicate that the mechanical properties of the RAC (with 100% of RCA) prepared through TSMA and SEMA were improved by 9.36 and 12.14% at 28 days. Perhaps, prolonged curing to TSMA and SEMA mixtures improved the mechanical properties of the RAC that is nearly equal to normal aggregate concrete (NAC) prepared by NMA.

scholarly journals Experimental study on noise reduction and performance enhancement for internal combustion engines

2020 ◽  
Vol 318 ◽  
pp. 01014
Author(s):  
Ioan Radu Şugar ◽  
Mihai Banica
Keyword(s):  
Experimental Study ◽  
Combustion Chamber ◽  
Noise Reduction ◽  
Fuel Consumption ◽  
Internal Combustion Engines ◽  
Performance Enhancement ◽  
Ceramic Materials ◽  
Combustion Engines ◽  
Large Cities ◽  
And Performance

As the number of cars increases and large cities become more and more crowded, noise reduction becomes more and more important. The decrease of the fuel consumption and the increase of power to the same cylindrical capacity are always current topics. This paper’s aim is to bring a contribution to solving these problems. The proposed solution consists in the use of ceramic materials in the design of the combustion chamber.

Thermal Behaviors in a Square Duct with U-Ribbed Tape Inserts

2014 ◽  
Vol 931-932 ◽  
pp. 1208-1212
Author(s):  
Chitakorn Khanoknaiyakarn ◽  
Sompol Skullong ◽  
Pongjet Promvonge ◽  
Nuthvipa Jayranaiwachira
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Performance Enhancement ◽  
Thermal Characteristics ◽  
Longitudinal Vortex ◽  
Experimental Result ◽  
Airflow Rate ◽  
Constant Heat ◽  
Square Duct ◽  
The One

This paper presents an experimental study on thermal characteristics in a constant heat-fluxed square-duct heat exchanger with U-ribbed tape inserts. The experiments are carried out by varying airflow rate for Reynolds number ranging from 4000 to 38,000. The insertion of the U-ribbed tape is performed with an axial rib-pitch set to four times duct-height (4H) at a single attack angle, α=45° and the ribbed tape is diagonally inserted in the square duct in order to generate longitudinal vortex flows. Effects of five blockage ratios (e/H=0.1, 0.15, 0.2, 0.25 and 0.3) on heat transfer and friction loss are experimentally investigated. The experimental result shows that the insertion of the U-ribbed tape at e/H=0.3 provides the highest heat transfer and friction factor values but the one at e/H=0.25 yields the highest thermal performance enhancement.

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