Aerodynamic Study Research Articles

Aerodynamic Study of Various Fins for Missile Body

Abstract: This study aims to analyse the flow characteristics and drag profiles of six different fin geometries - clipped delta, swept, trapezoidal, elliptical, rectangular, and triangular - for subsonic, transonic, and supersonic flow at different Mach numbers. By comparing the aerodynamic characteristics of these fin variants, the research aims to identify the most efficient fin geometry for each Mach regime. This study will benefit missile designers in selecting the most suitable fin geometry for their mission by providing information on the efficiency of each fin geometry at different Mach numbers. The findings of this research will enable the development of more efficient and effective fins for missile models

Data-driven prediction of critical flutter velocity of long-span suspension bridges using a probabilistic machine learning approach

Among the consequences of wind-induced excitation on long-span cable-supported bridges, flutter instability is the most dangerous and can collapse bridge structures. Until now, the flutter velocity of long-span bridges can be computed after conducting an experimental wind tunnel test or by means of computational fluid dynamics (CFD). However, the approaches mentioned above are cost-prohibitive and time-consuming especially when there are many sampling designs to evaluate. Therefore, it is crucial to develop an alternative solution for evaluating the flutter performance of such structures while minimizing the associated cost and computation time without worsening the accuracy of the results. Scholars have proposed machine learning (ML) techniques to address this issue. Unfortunately, some ML techniques do not provide excellent generalization for small datasets and are prone to bias even when the accuracy is relatively high. Besides, conventional ML models do not consider the uncertainty in data. This study proposes a probabilistic machine learning approach to overcome the weaknesses of the conventional ML models. The dataset used to train the proposed model was generated from 73 sampling designs using a fully numerical approach that involved 2D URANS (Unsteady Reynolds-averaged Navier-Stokes) CFD simulations, quasi-steady flutter theory, finite element model, and multi-mode approach for critical flutter velocity computation. The deck cross-section's most influential parameters and the critical flutter velocity constitute the datasets used to build the proposed probabilistic machine learning model. Our finding substantiates that the probabilistic machine learning approach based on hierarchical Bayesian modeling (PML-HBM) overperformed the conventional machine learning models, including extreme gradient boosting regression (XGBR), random forest (RF), and the support vector regression(SVR). Therefore, PML-HBM can accurately predict the critical flutter velocity. This model is an interesting approach to circumvent the time and cost associated with wind tunnel tests and CFD simulations at the earlier design stage of long-span bridge aerodynamic study.

Parametric aerodynamic and aeroelastic study of a deformable flag-based energy harvester for powering low energy devices

Extensive wind tunnel experiments were performed to find the optimal and most influential parameters for energy harvesting from piezoelectric membranes (thin elastic cantilevered plates), herein called flags. Four different piezoelectric flags were tested in conjunction with the seven different bluff bodies at various wind speeds and streamwise gaps between the bluff body and flag. Stiffness of the flags was also varied along with its length to assess the impact on harvested power. Various flapping modes are observed for different flags which correspond to the amount of harnessed power. The results revealed that altering the stiffness of flag can produce an increase of 29 and 31 times in power generation for long and short flags, respectively. It was found that the 120-degree bluff body produced the largest power with the capability to generate a strong wake region. Further analysis of the best performing flag (short and stiff) for various bluff bodies shows a remarkable increase of 661.2 % in generated power. This membrane shows rhythmic periodic flapping with higher modes of deformation in comparison to its other flag counterparts. These alternate flags show out-of-plane and twisting motion which wastes strain energy and causes a cancelation effect, reducing total energy output. The results show that in designing an efficient and reliable energy harvester, the flag’s stiffness and length as well as the shape of the bluff body play an important role. Furthermore, in comparison with the flutter phenomenon (i.e. a dynamic instability of the flag in the absence of a bluff body), the results with a bluff body demonstrate that higher energy generation can be achieved at a lower wind speed, thus paving the way for small and practical energy harvesting devices specifically in remote areas.

Prediction of Flow Field Over Airfoils Based on Transformer Neural Network

Airfoil flow field data acquisition is pivotal to the study of aerodynamics, traditionally relying on time-consuming computational fluid dynamics simulations or expensive wind tunnel tests. Herein, we introduce a new methodology leveraging Transformer Neural Network (TNN), which differs from conventional methodologies by employing self-attention mechanisms, to effectively predict these critical flow field data using historical data. A comprehensive set of experiments demonstrates the TNN model’s exceptional predictive accuracy, achieving over 95% across various airfoils under various operating conditions. Beyond accuracy and efficiency, we introduce an attention principle in our TNN model enhancing its interpretability. By aligning the TNN model’s attention distribution with the aerodynamic principles of airfoils, we illustrate how it utilises these geometric attributes in its predictions, thereby offering theoretical backing to its predictive outcomes. Our TNN model’s commendable accuracy, efficiency and interpretability illuminate the pathway for continued exploration in the fusion of deep learning with computational fluid dynamics.

Analysis of the influence of air quality on the performance of the Boeing 737-800 evaluated during takeoff at El Dorado Airport

This paper analyzes how the Bogotá’s air quality and pollutant levels affects the Boeing 737-800 take-off performance in terms of the available runway distances and maximum \newtext{take-off} weight, which are two of the most restrictive factors in airlines' operation. The airport runway's physical characteristics, geographical position, surroundings, and atmospheric conditions affect the maximum aircraft \newtext{take-off} weight. This study examines: (a) the influence of pollutants in Bogotá’s air quality and its subsequent effects in air density; (b) the maximum available polluting agents and relative humidity measures in this city; (c) the maximum take-off weight of the aircraft with and without air degradation due to atmospheric considerations. Software called “Aircraft Take-Off Software” has been developed to determine the B737-800 most limiting take-off weight of in specific geographical and atmospheric conditions. This study reflects the effect of high populated cities pollution on the aircraft operational performance which analysis has demonstrated that the presence of high carbon dioxide concentrations in the air increase the B737-800 payload capacity taking off from Bogotá but in the other hand, relative humidity variation decreases this capacity drastically, showing that considering Bogotá’s relative humidity and pollutant levels, the most restrictive weight situation for the take-off phase is the “Climb Limit Take-Off Weight”; however, as it is an aerodynamic study of the pollutants influence in engine combustion the structural integrity was not considered and for further investigation it should be considered to determine more accurately the most restrictive take-off weight.

Optimization Analysis of Race Car Design

Modern sports vehicles got enhanced in terms of performance by using better tools to design and analyze. The study of aerodynamics has always been a very intense, challenging as well as exciting task for professionals working on the research and development. This work presents the numerical analysis of our modeled race car aerodynamics and the simulation on it. We have studied different airfoils and used them in the rear wing. We studied the air flowover the body of the car at different velocities and its effect on the various aerodynamic parameters of the car, i.e., downforce/negative lift, stress, pressure and drag. We collected and tried to study what the numbers meant and analyzed the data which we got from the simulation solver. This was a tricky and time-consuming part as simulation has much to study and understand. Our aim was to get meaningful results from our simulation study. Our simulation study was without aero kit and with aero kit. In the following International Journal of Scientific Research in Engineering and Management (IJSREM) Volume: 07 Issue: 01 | January - 2023 Impact Factor: 7.185 ISSN: 2582-3930 © 2023, IJSREM | www.ijsrem.com DOI: 10.55041/IJSREM17557 | Page 2 sections we will further discuss and explain more in detail. Final conclusion of this project will be; to find outthe best fit airfoil and most efficient placement (angle of attack & height) of it in the rear of our modeled car. In this project we have designed a car, studied air flow over the body of the car at different velocities and its effect on the various aerodynamic parameters of the car i.e., downforce/negative lift, stress, pressure and drag.

Full-scale computational fluid dynamics study on wind condition of the long-span Queensferry Crossing Bridge

To date, the majority of numerical modelling [computational fluid dynamics (CFD)] studies on long-span bridges have been carried out on scaled physical models, and without field-data for validation. For the first time, a full-scale bridge aerodynamic CFD study was conducted in this paper. A full-scale three-dimensional CFD model of the middle span and central tower of the Queensferry Crossing, United Kingdom, was created. The aim of this work was accurately simulating the wind field around the bridge. The CFD simulations were developed in OpenFOAM with the k − ω SST turbulence model. Atmospheric boundary layer inflows were configured based on wind profiles provided by a full-scale Weather Research and Forecasting (WRF) model. CFD predictions were validated with field data which were collected from an on-site Structural Health Monitoring System. The simulated fluctuating wind field closely satisfied the characteristic of field data and demonstrated that the modelling approach had good potential to be used in practical bridge aerodynamic studies. Meanwhile, comparisons and sensitivity analyses on mesh density provided a reference modelling approach for any future works on full-scale bridge aerodynamic models. Additionally, a cylindrical-like domain was applied in bridge aerodynamics for the first time and verified as being a convenient and reliable way to be used in bridge studies that involve changes in yaw angle.

Aerodynamic study of the characteristics of the nest one skyscraper under wind load

To improve the safety and ease of use of super-tall buildings in strong winds, aerodynamic optimization of building shapes is considered the most effective approach. Aerodynamic optimization aims to solve a problem at its source, as opposed to structural optimization, which aims to improve the wind resistance of a structure. With the advancement of technology, buildings with complex plan shapes such as square and round, round and hexagonal, square and octagonal, etc. have been considered by many architects keeping in mind the aesthetics of the building. The wind flow around a high-rise building with complex plan shapes having different height ratios is different from what we get when analyzing a conventional shape. Since data on such buildings is not available, the need for wind tunnel or CFD testing becomes important to analyze the effects of wind on such buildings. CFD (computational fluid dynamics) for determining wind response is becoming extremely popular.

AERODYNAMICS OF CYLINDRICAL FINITE LENGTH BODIES

Studies were carried out in the test section of a closed-type wind tunnel. This paper presents the results of velocity distribution in the wake behind short cylinders. To study the effect of the relative length of short cylinders on the aerodynamics of the flow in the wake behind the body, the profiles of the mean velocity were measured in various sections behind short cylinders in the median planes coinciding with the cylinder axis and perpendicular to the cylinder axis. The calculation of resistance of transversely and longitudinally streamlined short cylinders is also given. To determine aerodynamic drag, cylinders with spherical and flat ends were used, as was an ellipsoid of revolution for comparison. The drag coefficient of a transversely streamlined ellipsoid of revolution is somewhat less than its value for a short cylinder at the same elongation of the bodies. In a longitudinal flow around a short cylinder with spherical ends and ellipsoids of revolution, the drag coefficients smoothly decrease with an increase in the Reynolds number to some minimum values. Based on the results of aerodynamic studies, the regularities of the flow around finite length cylinders with different ends shapes in a free air flow with longitudinal and transverse flow in a wide range of geometric and operating parameters have been established.

Aerodynamic Study and Design of Fixed Wing and Multi-copter Combination

This project aims to design a hybrid drone with fixed wing for the stable cruising as well as multi-copters for the vertical take-off and landing (VTOL) operations. Drones are utilized for number of applications leading from transportation to the surveillance purposes. Some drones are popular for their stable operation, while other for optimum landing and takeoff. Therefore, numerical analysis was performed on propeller, landing gear as well as on whole structure of the drone. The observed result from CFD analysis show that the velocity distribution had maximum velocity of 40 m/s at the mid span of the drone. In addition, the maximum stress obtained was on the landing gear with approximate value of 185 MPa which is due to the weigh and payload of the drone. The final model was built after the analytical and numerical analysis in order to achieve sustainable and reliable prototype.

Co-design and aerodynamic study on a two-step high pressure reducing system for hydrogen decompression: From hydrogen refueling station to hydrogen fuel cell vehicle

Fuel for hydrogen fuel cell vehicles comes from hydrogen refueling stations. During the hydrogen filling process, a high-pressure gradient from 35 MPa (hydrogen storage pressure) to 0.16 MPa (fuel cell pressure) is generated. Such a large pressure gradient posed a challenge to the design of the pressure reducing system. Traditional system is difficult to reduce hydrogen pressure from 35 MPa to 0.16 MPa without accompanying large noise and energy consumption. This work is exploring a new concept to combine the multi-stage continuous resistance perforated components and the Tesla valve to design a two-step high pressure reducing system for hydrogen decompression. To validate the superiority of the developed system, a detailed aerodynamic study on the new system is performed, since aerodynamic performance directly affects the operating flexibility and stability. Finally, the optimized co-design of the system is achieved. Results show that the new system is well-designed for hydrogen decompression with the function of control noise and energy consumption. Larger orifice radius (r1/r0) and orifice ratio (k) contribute the better aerodynamic performance. Angle α = 45° is considered the best for better aerodynamic performance. The descending order of the effects on better aerodynamic performance is angle (α), row (m), sleeve stage (N), orifice radius (r1/r0) and width (t1/t0). This study provides basic support for experts to achieve throttling design of related pressure control systems in hydrogen industry.

Assessment of increased energy efficiency of vehicles with a rational reduction of engine capacity

Problem. The tendency to reduce the working volume of internal combustion engines, which has emerged in recent years in the global automotive industry, is due to the need to improve the environmental situation and energy efficiency of road transport. Goal. The aim of the study is to increase the energy efficiency of vehicles by rationally reducing the maximum effective engine capacity. Methodology. The work uses the method of partial accelerations, implemented in a mobile registration and measurement complex, which allowed the authors to obtain an improved formula for calculating the force of aerodynamic resistance. Experimental studies of car aerodynamics were also carried out. Results. The article presents the results of the authors' research, which made it possible to prove the possibility of reducing the power of the internal combustion engine while maintaining the specified maximum speed and the specified level of indicators of the dynamic properties of cars. Originality. The relationship between the degree of use of the maximum engine power and the relative change in the effective specific fuel consumption of a carburetor gasoline engine with direct injection of gasoline and diesel is determined. Practical value. Calculations performed on the example of the ZAZ-1103 "Slavuta" car showed that a rational reduction in effective power allows for a 9.5% reduction in fuel consumption, and for an engine with direct injection of gasoline and diesel engines, this leads to an increase in fuel consumption by 6.7 % and 20.3%, respectively.

Study of sports car aerodynamics using computer simulation methods

Problem. The results of the value of the coefficient of aerodynamic resistance of a sports car and the calculations of the frontal area of ​​its three-dimensional model are given. Goal. The goal is determination of the coefficient of aerodynamic resistance for a sports car by means of a computer experiment and justification of the feasibility of using attached parts to improve aerodynamics. Methodology. The method of computer experiment and three-dimensional modeling was used based on a comparison with the geometric and technical characteristics of a real car The results The accuracy of the construction of the three-dimensional model and virtual experiment was confirmed based on the obtained values of the frontal area and the coefficient of aerodynamic resistance.

The gravity field and gravity data reduction across the continental area of Nigeria

This research presents the variation of the gravity field and associated gravity field components over the continental area of Nigeria to provide data for geoscience research, geodetic and engineering works, aerodynamic studies and deep crustal inferences. Accurate positions and elevations were observed at 58 of the 59 base stations of the Primary Gravity Network of Nigeria (PGNN), whose absolute gravity values had been accurately determined. The absolute gravity values were plotted against their respective positions to reveal the distribution pattern and strength of the gravity field within the study area. Theoretical gravity values at each base station were generated using the Somigliana's equation. The free-air gravity and free-air anomaly gravity values were generated with respect to the World Geodetic System 1984 (WGS84) ellipsoid using GPS-derived elevation data. Then, the perturbing potential, free-air gravity with respect to the geoid, and the indirect effects were evaluated. The average of the indirect effects was used to adjust the WGS84 gravity formula to produce a gravity formula that better approximates the geoid across the continental area of Nigeria, compatible with the heights measured relative to the geoid, which can serve as a reference for establishing a vertical height control. The Bouguer gravity and Bouguer gravity anomalies across Nigeria revealed a “trans-southern gravity high strip” interpreted to be associated with mantle upwelling. Two new major mega-lineaments related to mantle upwelling were mapped. A batholith province trending NW–SE was delineated, occurring from north central Nigeria to the north western region and containing closures of “Bouguer gravity lows” interpreted as batholiths. A separate closure of “Bouguer gravity low” was detected at Azare, north eastern Nigeria, which may be due to the presence of intrusive granitic body. It is recommended that the mantle structure beneath “the trans-southern gravity high strip”, “delineated batholith province” and “isolated gravity closures” around the northeast of Nigeria should be studied from seismic shear wave splitting analysis for better understanding of the deep lithospheric structures and moho relief.

Wind tunnel research, dynamics, and scaling for wind energy

The interaction of wind turbines with turbulent atmospheric boundary layer (ABL) flows represents a complex multi-scale problem that spans several orders of magnitudes of spatial and temporal scales. These scales range from the interactions of large wind farms with the ABL (on the order of tens of kilometers) to the small length scale of the wind turbine blade boundary layer (order of a millimeter). Detailed studies of multi-scale wind energy aerodynamics are timely and vital to maximize the efficiency of current and future wind energy projects, be they onshore, bottom-fixed offshore, or floating offshore. Among different research modalities, wind tunnel experiments have been at the forefront of research efforts in the wind energy community over the last few decades. They provide valuable insight about the aerodynamics of wind turbines and wind farms, which are important in relation to optimized performance of these machines. The major advantage of wind tunnel research is that wind turbines can be experimentally studied under fully controlled and repeatable conditions allowing for systematic research on the wind turbine interactions that extract energy from the incoming atmospheric flow. Detailed experimental data collected in the wind tunnel are also invaluable for validating and calibrating numerical models.

Analyzing Wind Direction Flow Control on Full-Scale Amphibious Assault Ship Airwakes Using a Computational Fluid Dynamics Simulation

Lu, Y.; Shao, W.; Chang, X.; Chuang, Z., and Zhou, Z., 2022. Analyzing wind direction flow control on full-scale amphibious assault ship airwakes using a computational fluid dynamics simulation. Journal of Coastal Research, 38(6), 1181–1194. Coconut Creek (Florida), ISSN 0749-0208. This paper presents an aerodynamic study on flow control by different wind directions on full-scale amphibious assault ship (AAS) airwakes using computational fluid dynamics (CFD). The Reynolds-averaged Navier-Stokes (RANS) equation was employed to conduct a numerical simulation for the analysis of aerodynamic characteristics of the ship airwake flowfields under wind impacting. The aerodynamic performance of a small-scale landing helicopter assault (LHA) model was first simulated and then validated with Particle Image Velocimetry experimental data from the VSHAIP project of the NASA Ames Research Center. Employing CFD simulations, the computed unsteady ship airwakes compared well to experimental data. After validation, full-scale AAS airwakes were further simulated by CFD to capture the vortex patterns and velocity distributions of winds in the Head, Red, and Green directions surrounding the AAS. Building on this, the range of wind direction angles of relatively stable vertical wind speed above each landing point is discussed. The aerodynamic analysis and numerical method described in this study will build a strong foundation supporting the numerical simulation of the ship airwakes in full scale as well as small scale.

Reliability Analysis of a Wind Turbine Blade

In the context of sustainable development, given the double planetary challenge posed by the imminent depletion of fossil energy resources and the damaging effects of fossil fuels on nature, renewable energies are emerging as a good alternative. Today, the installation of wind parks is increasing worldwide, and aerodynamic research on wind turbines is highly specialized. By using Computational Fluid Dynamics (CFD), it is possible to evaluate the influence of loads on the aerodynamic performance of the wind turbine blade. In order to increase its performance and reliability, a good modelling of the airflow around the turbine is very important. In this paper, the study is divided into three parts. First, the aerodynamic study of the blade has been performed with ANSYS CFX. Secondly, the modal analysis in pre-stressed mode has been carried out to find the natural frequencies of the blade with ANSYS MECHANICAL. Then the last part is devoted to the reliability study of the wind turbine blade with FORM and SORM methods developed with a MATLAB code.

Prospective voice assessment after uncomplicated thyroidectomy: A comprehensive analysis of a single centre experience.

Voice change after uncomplicated thyroidectomy has been an important issue in the field of thyroid surgery. The aim of this study was to promote understanding of voice change after uncomplicated thyroidectomy by analysing the results for a large number of patients from a single institute. We retrospectively reviewed the medical records of 2879 consecutive patients who underwent thyroidectomy and voice evaluation between January 2014 and December 2019 in a single institute. All the patients had their vocal status assessed using videostroboscopy, acoustic voice analyses, aerodynamic study, and Thyroidectomy-related Voice and Symptom Questionnaire (TVSQ) scores preoperatively and at 1, 3, and 6months postoperatively. We analysed the pattern of voice changes over time and differences in voice parameters based on clinical factors. To confirm the usefulness of the TVSQ, the correlation between TVSQ scores and objective parameters was analysed. Lastly, predictive factors for persistent voice symptoms were analysed. Tertiary referral hospital. The frequency ranges and TVSQ scores exhibited significant deterioration until 6months following surgery. Among clinical factors, the extents of thyroidectomy and neck dissection were associated with worse voice parameters. The TVSQ score was significantly correlated with objective voice parameters. The extents of thyroidectomy and neck dissection were predictive of persistent voice symptoms at 6months after thyroidectomy. After uncomplicated thyroidectomy, most voice parameters tended to recover, but some parameters remained aggravated even at 6months after surgery. With more extensive surgery, worse voice quality and the higher risk of persistent voice symptoms may be anticipated.

Freestream Turbulence Effects on the Aerodynamics of an Oscillating Square Cylinder at the Resonant Frequency

Flow past a bluff body in freestream turbulence can substantially change the flow behaviour compared to that in smooth inflow. This paper presents the study of wake flow and aerodynamics of an oscillating square cylinder at the resonant frequency in freestream turbulence, with the integral length not greater than the cylinder side and the turbulence intensity not greater than 10%. Large eddy simulations (LES) in the Cartesian grid using the Immersed Boundary Method (IBM) technique embedded in a FVM solver, together with an efficient synthetic turbulent inflow generator implemented in an in-house parallel FORTRAN code are used for the study. The results are compared with those for smooth inflow, and relevant data published in the literature. The key findings are: the freestream turbulence conditions evidently reduces the local turbulent scales and fluctuations in the shear layer compared to in smooth flow, as small scale freestream turbulence breaks down cylinder-generated larger scale eddies and weakens them; but does not evidently affect the vortex shedding frequency, or the length of the recirculation region behind the cylinder. This suggests negligible change of drag coefficient compared to in smooth inflow. Moreover, this is because the vortex shedding is dominated by the forced oscillation at the resonance frequency, and the turbulence intensity is small.

Performance Analysis of PLA Material Based Micro-Turbines for Low Wind Speed Applications.

Various studies have been conducted in recent years to find solutions to the issues in wind energy conversion systems. A 100W horizontal axis micro wind turbine is built for low wind speed applications in this work. The Blade Element Momentum theory approach was used to design the 100W micro wind turbine blade. The wind turbine blade 3D model was created using the CREO CAD 3.0 software. Based on the aerodynamic studies, the airfoil S9000 is chosen among others for generating high power at low wind speed. The density, Young’s modulus, and the Poisson ratio of the proposed wind turbine blade model with acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) materials were compared. ABS and PLA materials were investigated using a 0.33 mm layer of infill ranging from 10% to 100%. PLA and ABS output values were compared in terms of deformation, equivalent stress, and equivalent strain. PLA materials, on the other hand, have less deformation and greater structural properties than ABS materials. The wind blade structural analysis was performed in ANSYS 15 software, and the details of experimental and simulated results are presented in this paper.