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Many aircraft, like fighters and bombers, are delta-winged aircraft. These aircraft have the characteristics of producing a greater lift at very small angles of attack even at very low Reynold’s number. Highly swept-wing aircraft experience greater lift due to the generation of the leading-edge vortex at a high angle of attack flight. The phenomena of vortex breakdown are noticed which leads to the reduction of the vortex lift and leads to the instability of the aircraft. This paper deals with an analysis of the flow on the delta wing with the existing literature and compares its benefits over the conventional wings using experimental and computational methods. The critical angles, pressure, and velocity variations are observed along with chord and spanwise locations.

Purpose This paper aims to model the aerodynamic flow characteristics of NACA0010 for various angle of attacks including stall for incompressible flows using panel methods. This paper also aims to quantify the surface pressure distribution on streamlined bodies and validate the results with analytical Jukouwski method and inverse panel methods that can predict the aerodynamic flow behaviour using the geometric iteration approach. Design/methodology/approach The 2 D panel method was implemented in Qblade software v.06 which uses the fundamental panel method which rely on source strengths and influence coefficients to determine the velocity and pressure fields on the surface. The software implements the boundary layer or viscous effects to determine the influence on aerodynamic performance at various angles of attack. Jukouwski method is also evaluated for predicting aerodynamic characteristics and is based on the geometric iteration approach. Then complex aerodynamic flow potentials are determined based on the source strengths which are used to predict the pressure and velocity fields. Findings At low to moderate angles of attack, panel and Jukouwski methods predict similar results for surface pressure coefficients comparable to Hess and Smith inverse method. In comparison to panel method, results from the Jukouwski mapping method predicted the pressure coefficient conservatively for the same free stream conditions. With increase in Reynolds number, lift coefficient and aerodynamic performance improved significantly for un-tripped aerofoil when stall angle is approached when compared to tripped aerofoil. Practical implications This study demonstrated that panel methods have higher efficacy in terms of computational time or resources and thus can provide benefits to many real-world aircraft or aerospace design applications. Originality/value Even though panel and Jukouwski methods have been studied extensively in the past, this paper demonstrates the efficacy of both methods for modelling aerodynamic flows that range between moderate to high Reynolds number which are critical for many aircraft applications. Both methods have been validated with analytical and inverse design methods which are able to predict aerodynamic flow characteristics for simple bluff bodies, streamlined aerofoils as well as bio-inspired corrugated aerofoils.

Wind turbine noise is a critical issue for siting and its operation in offshore and terrestrial conditions. In this work, we analysed trailing edge bluntness vortex shedding noise source for a land based turbine of size 2MW and blade span of 38m using modified BPM noise solver. A regression approach has been implemented to predict the shape function in terms of thickness to chord ratio of aerofoils used for blade. For trailing edge height of 1 % chord, computations for sound power level were done at wind speed of 8m/s, 17 RPM, and showed that present regression approach predicts the noise peak of 78dBA at f ~ 10 kHz. These results were also validated using experiment data from GE 1.5sle, Siemens 2.3MW turbines with blade lengths of 78 -101m and agreed within 2 % at very high frequencies, f > 5kHz. In addition, results from present approach agreed with original BPM and modified BPM by Wei et al at high frequencies, f ~ 10kHz where the bluntness noise becomes predominant. The slope of noise curves from present approach, and modified BPM methods are lower when compared with original BPM and show sound level coincidence with peak Strouhal number of ~ 3.3.

Wing structures as found in aircrafts and wind turbine blades are developed using airfoils. Computational methods are often used to predict the aerodynamic characteristics of such airfoils, typically the pressure, lift and drag force coefficients. In the present work, surface pressure coefficient distribution of NACA 0010 is evaluated using the 2D panel and Jukouwski methods for incompressible lifting flows for three Reynolds numbers, Re–3 x105, 5 x105, 1 x 106. The analysis was conducted for various AOA (angle of attack), between –20 to 100 for the airfoil with tripped and untripped conditions. The non–dimensional pressure coefficient along chord direction of airfoil is illustrated for upper and lower surfaces between –20 to 100 angle of attack. The coefficient of lift and drag as well as glide ratio are evaluated for all three Reynolds numbers. The present results from the 2D panel method are validated using the results from Hess and Smith, inverse design methods implemented on conformal mapped symmetric Jukouwski airfoil of 10% thickness to chord at 40 angle of attack.

Aerodynamic performance of aircraft wings vary with flight path conditions and depend on efficiency of high lift systems. In this work, a study on high lift devices and mechanisms that aim to increase maximum lift coefficient and reduce drag on commercial aircraft wings is discussed. Typically, such extensions are provided to main airfoil along span wise direction of wing and can increase lift coefficient by more than 100% during operation. Increasing the no of trailing edge flaps in chord wise direction could result in 100% increment in lift coefficient at a given angle of attack but leading edge slats improve lift by delaying the flow separation near stall angle of attack. Different combinations of trailing edge flaps used by Airbus, Boeing and McDonnel Douglas manufacturers are explained along with kinematic mechanisms to deploy them. The surface pressure distribution for 30P30N airfoil is evaluated using 2D vortex panel method and effects of chord wise boundary layer flow transitions on aerodynamic lift generation is discussed. The results showed better agreements with experiment data for high Reynolds number (9 million) flow conditions near stall angle of attack.

Wind power plants produce energy by utilising the kinetic energy available from wind. Turbine blades undergo millions of revolution during lifetime and subjected to wear and tear due to unsteady ae...

Noise prediction from streamlined bodies such as wind turbine blades can be predicted accurately using CFD computations that use spatio-temporal turbulence models at the expense of high computational power. In this work, empirical methods proposed from BPM, Grosveld and Lowson are used to compute numerically to analyse the influence of rotor solidity factor on broadband trailing edge noise from a 2 MW horizontal axis wind turbine with a blade length of 37 m. Inputs to acoustic solver are the velocity vector field and boundary layer data which are obtained using blade element momentum and X-Foil. The outputs from acoustic solver are directivity and far field sound pressure on a receiver located at distance of 120 m from tower base. The results have shown that for a wind speed of 10 m/s measured at 10 m above ground, sound power level was found to increase between mid-bands to high frequencies for all three methods. Rotor solidity effect was illustrated at constant rotational speed of 17 RPM and receiver height of 0.5 m located in downwind position. A minimum difference of 1.5dBA was found at f ~ 100 Hz for Lowson method and maximum of ~ 2.8dBA at 1 kHz between two and three blade rotor. For BPM and Grosveld methods however, the sound levels were ~ 5dBA lower for two blade rotor than three blade rotor between f ~ 100 Hz and f ~ 1 kHz. The study also demonstrated that as number of blades increase by integral multiples, the effect on noise radiation from trailing edge of blades increase by 2-5dBA due to amplitude modulation.

Wind turbine noise is becoming a critical issue for many offshore and land-based wind projects. In this work, we analyzed trailing edge bluntness vortex shedding noise source for a land-based turbine of size 2 MW and blade span of 38 m using original Brooks Pope and Marcolini (BPM)and modified BPM noise model. A regression-based curve fitting approach has been implemented to predict the shape function in terms of thickness to chord ratio of aerofoils used for blade. For trailing edge height of 0.1% chord, computations for sound power level were done at wind speed of 8 m/s, 17 RPM. The results showed that present approach for thickness correction predicts the noise peak of ∼78dBA at f ∼ 10 kHz which is ∼15dBA lower than that predicted from original BPM. The results were also validated using experiment data from GE 1.5sle, Siemens 2.3 MW turbines with blade lengths between 78 m and 101 m which agreed within 2% at high frequencies, f > 5 kHz. In addition, results from present approach for trailing edge bluntness noise agreed well with modified BPM by Wei et al. at high frequencies, f ∼ 10 kHz where it becomes dominant. The slope of noise curves from present approach, and modified BPM methods are lower when compared with original BPM.

An important aerodynamic noise source from lifting surface occurs from trailing edge of an aerofoil as found in wind turbine blades. In this work, semi-empirical method proposed by Brookes, Pope, Marcolini is applied to evaluate trailing edge bluntness vortex shedding noise source. For low Mach number flows (0.1884) and moderate to high chord Reynolds number, 4.73 × 10 5 -3.35 × 10 6 , change in sound power level was assessed for trailing edge thicknesses in terms of 0.1%, 0.5% and 1% chord lengths at wind speeds of 8 m/s, 10 m/s. For overall change of trailing edge thickness from 0.1% to 1% chord, an increase in noise levels up to 50 dB was found at low frequencies, while a decrease up to 30 dB was found between mid-band to high frequencies of spectra.

Corrugations are folds on a surface as found on wings of dragon fly insects. Although they fly at relatively lower altitudes its wings are adapted for better aerodynamic and aero-elastic characteristics. In the present work, three airfoil geometries were studied using the 2-D panel method to evaluate the aerodynamic performance for low Reynolds number. The experiments were conducted in wind tunnel for incompressible flow regime to demonstrate the coefficients of lift drag and glide ratio at two Reynolds numbers 1.9x104 and 1.5x105 and for angles of attack ranging between 00 and 160. The panel method results have been validated using the current and existing experiment data as well as with the computational work from cited literature. A good agreement between the experimental and the panel methods were found for low angles of attack. The results showed that till 80 angle of attack higher lift coefficient and lower drag coefficient are obtainable for corrugated airfoils as compared to NACA 0010. The validation of surface pressure coefficients for all three airfoils using the panel method at 40 angles of attack was done. The contours of the non-dimensional pressure and velocity are illustrated from -100 to 200 angles of attack. A good correlation between the experiment data and the computational methods revealed that the corrugated airfoils exhibit better aerodynamic performance than NACA 0010.

Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies. Resumo A turbulência atmosférica é um fenômeno instável encontrado na natureza e desempenha um papel significativo na previsão de eventos naturais e na previsão da vida de estruturas. Neste trabalho, a turbulência na camada limite superficial foi estudada por meio de métodos empíricos. Simulação computacional de Von Karman, métodos Kaimal foram avaliados para diferentes rugosidades superficiais e para intensidades de turbulência baixa (1%), média (10%) e alta (50%). Valores instantâneos de séries temporais de um minuto para vento turbulento longitudinal com velocidade média do vento de 12 m/s usando ambos os espectros mostraram forte correlação nas tendências de validação. A influência das escalas de comprimento integral na produção de energia cinética de turbulência em diferentes alturas é ilustrada. Séries temporais para velocidade média do vento de 12 m / s com rugosidade de superfície de 0,05 m mostraram que a variância para os componentes de velocidade longitudinal, lateral e vertical foram diferentes e considerados anisotrópicos. A densidade espectral da potência da velocidade do vento dos perfis de Davenport e Simiu também foi calculada na rugosidade da superfície de 0,05 m e comparada com inclinações k−1 e k−3 para a lei Kolmogorov k5/3 em subfaixa inercial e k−7 em viscoso faixa de dissipação. Em altas frequências, a inclinação logarítmica da lei Kolmogorov −5/3rd concordou bem com os espectros de Davenport, Harris, Simiu e Solari do que em baixas frequências.

In this work, the numerical approach is used to verify the aero/hydrodynamic performance of different geometries of nose cones. Computational methods predict the flow characteristics fairly accurately in order to validate the data obtained from experiments. The simulation involves muzzle velocity that range from 5 m/s to 25 m/s the corresponding Reynolds numbers ranges from 1.69 to 8.4 x 105 and calculated for the different angle of attack, -10 to 20 degrees, to demonstrate the flow behavior around the different nosecone shaped shells. Nosecone is the most forward section of any slender moving bodies which are used in rockets, guided missiles, submarines, aircraft drop tanks and aircraft fuselage to reduce the aerodynamic or hydrodynamic drag. The basic geometry of bluff body is cylinder with variant nosecone shapes such as flat and tapered head, with moderate to low taper ratios and conical head. The aerodynamic characteristics like lift, drag and pressure distribution of the cylinder with different nosecones are illustrated for low subsonic speed for the same length to diameter ratio. The best results are obtained for cylinder with conical nosecone and better similar results observed for cylinder with shapes having low and medium taper.

Multi element airfoils are high lift devices and provide improved aerodynamic characteristics which are beneficial for several applications such as aircraft wings wind turbine blades Simulations were performed using the computational panel code developed in MATLAB for the airfoils P N GA W RAF NLR configurations The results were obtained for varying angle of attacks from to deg to include the effects of turbulence The lift and drag coefficients are evaluated for the airfoil configurations P N for Reynolds number range of x x The velocity and pressure contours distributions are illustrated to predict the laminar to turbulent flow characteristics on the airfoil surface The maximum lift coefficient for single slotted flap element is found to decrease for large angle of attack beyond the stall region and for slat element the increase in lift is found to be marginal at high angle of attack The maximum lift coefficient obtained including flap and slat elements is and the drag coefficient is

Research on broadband aerodynamic noise from wind turbine blades is becoming important in several countries. In this work, computer simulation of acoustic emissions from wind turbine blades are predicted using quasi empirical model for a three-bladed horizontal axis 3 MW turbine with blade length ~47 m. Sound power levels are investigated for source and receiver height of 80 m and 2 m above ground and located at a distance equal to total turbine height. The results are validated using existing experimental data for Siemens SWT-2.3 MW turbine having blade length of 47 m, as well as with 2.5 MW turbine. Aerofoil self-noise mechanisms are discussed in present work and results are demonstrated for wind speed of 8 m/s. Overall sound power levels for 3 MW turbine showed good agreements with the existing experiment data obtained for SWT-2.3 MW turbine. Noise map of single source sound power level, dBA of an isolated blade segment located at 75 %R for single blade is illustrated for wind speed of 8 m/s. The results demonstrated that most of the noise production occurred from outboard section of blade and for blade azimuth positions between 80° and 170°.

Wing structures as found in aircrafts and wind turbine blades are built from airfoils. Computational methods are often used to predict the aerodynamic characteristics of airfoils, typically the force and pressure coefficients along its chord length. In the present work, pressure coefficient distribution of NACA 0010 is evaluated using the 2D panel method for incompressible lifting flows at moderate to high Reynolds number, Re-3 x105, 5 x105, 1 x 106. The analysis was conducted for various AOA (angle of attack), between -40 to 200 for the airfoil. The non-dimensional pressure is illustrated for upper and lower surfaces of airfoil between 00 to 200 angle of attack at specific chord locations of airfoil. The present results from the 2D panel method are validated using the results from Hess & Smith method and inverse airfoil design method implemented on conformal mapped symmetric Jukouwski airfoil of 10% thickness at 40 angle of attack.

In this paper BEM & Glauert theory of momentum are investigated for the magnitude of axial induction factor, thrust coefficients and axisymmetric pressure distribution by Kinner. The axial induction factor characteristic is analyzed around the rotor blade in order to determine the extent of velocity gradient in the flow stream relative to free stream. The influence of yaw and wake skew angles on the power coefficient of turbine is analyzed for axial induction factor variation, from tip of blades in the wake stream and when blade passes the tower. The lift and drag coefficients vary with angle of attack and tip speed ratios which enables to determine the behavior of axial and tangential induction factor observed at different blade locations. The axial induction factor is calculated also according to the azimuthal averaged positions of the turbine rotor during the operation.