Aerodynamic Profile Research Articles

Study on the aerodynamic characteristics of reentry capsule with obtuse head inverted cone under hypersonic chemical nonequilibrium flow

Abstract During spacecraft reentry, the aerodynamic characteristics of the reentry capsule with a sizeable obtuse head inverted cone (OBHIC) in a hypersonic state are the key factors in the design of controlled reentry trajectory, the design of trim angle of attack (AoA), and the accuracy of fall point of capsules. This paper establishes a numerical simulation algorithm of a hypersonic chemical nonequilibrium flow field by considering high-temperature real gas effects. The reentry capsule’s aerodynamic and flow field characteristics are predicted and analyzed. The component transport equations for chemical reactions are added to the Navier-Stokes equations, enabling precise modeling of gas molecule vibrational excitation and ionization processes. A half-model multi-block structured mesh is employed to construct the aerodynamic profile of the reentry capsule with OBHIC. The aerodynamic characteristics and pressure distribution of the reentry capsule were calculated and analyzed under the typical conditions of flight altitude of 40~80 km, flight velocity of 6~27 Ma, and AoA of 15°~24°. The results of the aerodynamic characteristics prediction show that the aerodynamic characteristics of the reentry capsule are little affected by the incoming flow velocity in a hypersonic state but significantly affected by the AoA. As the AoA increases, the lift coefficient CL increases linearly, the drag coefficient CD decreases linearly, the lift-to-drag ratio K rises linearly, and K increases from 0.19 to 0.29. In its hypersonic state, the reentry capsule exhibits a low lift-to-drag ratio, characterized by high drag and low lift coefficients. The results of this paper play an essential role in the reentry flight dynamics and reentry trajectory design of the reentry capsule. Moreover, it can further ensure the safety and reliability of the reentry flight of spacecraft.

Modulating local winds and turbulence around a single building obstacle with the obstruction of tall vegetation

Strategic vegetation placement can significantly alter airflow patterns and turbulence, fostering desired wind environments. By comparing scenarios where vegetation is placed upstream, downstream or absent (treeless) relative to a single building using large-eddy simulation, this study provides detailed insights into the sensitivity of flow dynamics to the positioning of the vegetation. Upstream vegetation more significantly disrupts the flow patterns around the building obstacle, altering vertical wind profiles and modifying wake circulations, compared to downstream vegetation. A small shear layer developed at the plant top for upstream vegetation markedly influences turbulent kinetic energy (TKE) on both the leeward and windward sides of the building, shifting the inflection point in vertical TKE profiles by up to 0.13H. By contrast, smaller tree-building separations lead to an effective merging of their aerodynamic profiles, whereas larger separations confine the streamwise breadth of turbulent fluxes, amplifying flux exchanges in the spanwise direction. Spectral analyses reveal that upstream vegetation consistently results in higher power spectral densities of the streamwise turbulence in the residential area than downstream vegetation. While small-scale spanwise velocity fluctuations are found to be comparably energetic at the building's windward side for upstream vegetation, the power becomes substantially concentrated on large-scale eddies in the building wake region, providing specific insights into modulating turbulent eddy motions within the residential zone.

Design of a Human Muscle-Powered Flying Machine

This study explores the design and development of a human-powered aircraft (HPA), leveraging modern engineering techniques, materials science, and advanced CAD/CAM tools. The project addresses key aspects of aircraft design, including the geometry of wings and tail, control and power transmission mechanisms, propeller selection, and material identification to achieve ultra-lightweight construction. The 3DExperience platform facilitated comprehensive model creation, simulation, and production process development, while XFLR5 was employed for aerodynamic profile analysis using the vortex lattice and panel methods. JavaProp aided in evaluating propeller thrust and power requirements. Computational fluid dynamics (CFD) simulations using the SST k-ω turbulence model provided critical insights into flow behavior. The design was found to be theoretically capable of flight, although challenges arose in selecting appropriate software for aerodynamic analysis, leading to the use of XFLR5 for early-stage design and the more advanced 3DExperience platform for final evaluations. Although structural strength analyses were not performed due to the complexity of composite materials, future work in this area could enhance the precision of component selection and aircraft mass estimation.

Ultimate strength prediction of composite laminates containing straight-sided holes, scarfed holes, and bonded repairs

Scarfed repairs are well suited to load carrying aerospace structures because they can improve the strength of a damaged composite laminate while maintaining a smooth aerodynamic profile. However, the strength prediction of such composite repairs is challenging, with strength depending upon the size and shape of the geometric features causing stress concentrations and the laminate stacking sequence. New semi-analytical and finite element analysis strength models are presented along with experimental verification for laminates containing circular and elliptically shaped straight-sided holes, scarfed holes, and adhesively bonded repairs. The new semi-analytical model for open hole ultimate strength is an extension of the point stress criterion. The model can estimate the characteristic damage length based on material properties, stacking sequence, hole shape, and hole size. Strength predictions for adhesively bonded repairs are also presented. The semi-analytical models are comparable in accuracy to the more computationally expensive continuum damage finite element models for the wide range of panels tested, and both model predictions are in close correlation with experimental results.

Development and Measurement of a Very Thick Aerodynamic Profile for Wind Turbine Blades

Development and Measurement of a Very Thick Aerodynamic Profile for Wind Turbine Blades

Dynamic stall modeling of wind turbine blade sections based on a data-knowledge fusion method

Dynamic stall often leads to unsteady load and performance degradation in horizontal axis wind turbines. Therefore, accurate modeling of dynamic stall is crucial. However, due to the large variations of the blade aerodynamic profiles and the complexity of dynamic stall flow, numerical simulation and wind tunnel experiment are costly. On the other hand, widely used semi-empirical models have limited accuracy. Hence, this paper proposes a data-knowledge fusion method that incorporates physical knowledge into a neural network to improve its accuracy and generalization ability. Firstly, the force components of the Leishman–Beddoes model are incorporated into the network. An efficient dynamic stall model for the S809 airfoil is thus established with a small amount of high-precision experimental data. It achieves extrapolation predictions of reduced frequency and angle of attack with only 1/5 of the samples in the database to train. Moreover, to make full use of the accumulated existing airfoil data to assist in modeling other airfoils, the obtained S809 model is fused in the network to predict the aerodynamics of S810 and S814. The average relative error of the prediction cases is nearly 10%. Comprehensively, this paper provides a new paradigm for assessing the dynamic stall of the wind turbine blade.

Optimization study on airfoil aerodynamic performance with local indentation treatment based on drainage characteristics of dolphin fluke

Enhancing the aerodynamic performance of airfoils is the key to optimizing the energy harvesting efficiency of rotating machinery such as wind turbines. Motivated by the bowl-shaped outline of the dolphin's fluke during the propulsion process, this paper proposes a local indentation method that generates a concave region on the pressure surface of the airfoil. The NACA 0018 airfoil is selected as the reference airfoil, and two types of treatments are applied near the trailing edge point: rigid deformation and flexible deformation. Based on the grid quantity independence and experimental results validation, the results demonstrate that compared with the original airfoil, the local indentation method can modify the pressure distribution of the indentation section itself and optimize the airfoil's overall aerodynamic performance. The lift coefficient of the whole airfoil increases gradually with the rise in the indentation depth and reaches a stable value eventually. Quantitative results reveal that when the indentation depth D = 0.020c, the lift coefficient of the whole airfoil can increase by up to 26.27%; when the indentation depth D = 0.010c, the airfoil's lift-to-drag ratio reaches the maximum, which is 16.39% higher than that of the original airfoil. When replacing the rigid indentation section with a flexible medium, the fluid flowing over the pressure surface interacts with the flexible medium. The method of local indentation proposed in this paper can provide valuable reference for optimizing the aerodynamic profile of airfoils and improving the energy harvesting efficiency of wind turbines.

Advancing Wind Energy Efficiency: A Systematic Review of Aerodynamic Optimization in Wind Turbine Blade Design

Amid rising global demand for sustainable energy, wind energy emerges as a crucial renewable resource, with the aerodynamic optimization of wind turbine blades playing a key role in enhancing energy efficiency. This systematic review scrutinizes recent advancements in blade aerodynamics, focusing on the integration of cutting-edge aerodynamic profiles, variable pitch and twist technologies, and innovative materials. It extensively explores the impact of Computational Fluid Dynamics (CFD) and Artificial Intelligence (AI) on blade design enhancements, illustrating their significant contributions to aerodynamic efficiency improvements. By reviewing research from the last decade, this paper provides a comprehensive overview of current trends, addresses ongoing challenges, and suggests potential future developments in wind turbine blade optimization. Aimed at researchers, engineers, and policymakers, this review serves as a crucial resource, guiding further innovations and aligning with global renewable energy objectives. Ultimately, this work seeks to facilitate technological advancements that enhance the efficiency and viability of wind energy solutions.

A coupled FEM-FFT concurrent multiscale method for the deformation simulation of CFRPs laminate

Carbon fiber reinforced polymer composites (CFRPs) laminate is increasingly used in aircraft structures and its assembly deformation has great influence on the aircraft aerodynamic profile and mechanical performance. Due to the inherent multiscale nature of CFRPs, the traditional macroscopic models are unable to incorporate their true microstructural details, resulting in them being unable to provide both the macro and micro deformations simultaneously. To address this issue, this work proposed a coupled FEM-FFT concurrent multiscale method for the deformation simulation of CFRPs laminate, where the mechanical response of each macro point of CFRPs laminate was from the corresponding unidirectional representative volume element (UD RVE). The FEM (Finite Element Method) was used for the analysis at the macroscopic scale, while the FFT (Fast Fourier Transform) based method was employed in the UD RVE to speed up the calculation. The elastoplastic behavior of resin matrix in the UD RVE was modelled with the parabolic yield criterion. The proposed concurrent multiscale method was validated respectively by the tension, compression and shearing experiments of CFRPs laminate. The results show that there is a good agreement both for the full strain field and load–displacement curve, demonstrating the effectiveness of the proposed concurrent multiscale method.

Ice shedding tests for the assessment of hybrid ice protection systems

In technical areas, the prevention of atmospheric icing on structures is imperative due to safety risks and potential technical failures it poses. Recent development projects have focused on hybrid ice protection systems, combining active elements (heaters/mechanical actuators) with passive icephobic coatings. However, there is a lack of test strategies for the early development stages of these coating materials. An efficient test design for an ice wind tunnel is described here, developed to quantitatively assess the ice shedding effects facilitated by icephobic surfaces in electro-thermal ice protection systems. Dependencies on test and surface parameters are explored, laying the groundwork for defining test procedures for subsequent surface evaluations. During testing, utilizing a hydrophobic model coating, a reduction in energy of over 30% was observed compared to uncoated aluminium. This finding highlights the potential effectiveness of icephobic surfaces in mitigating icing effects. The presented test serves as a valuable tool for pre-selecting the most promising surfaces for further advanced tests, particularly those involving aerodynamic profiles within the ice wind tunnel test facility. It constitutes a vital component of a comprehensive test pyramid, encompassing ice-related tests with increasing complexity. Furthermore, the results obtained from these tests are utilised to establish correlations with surface properties, thereby enhancing our understanding of the significance of these findings. This approach provides a well-founded testing strategy for evaluating and advancing icephobic surface technologies.

Design Of Tangentially Fired Pulverized Coal Burner Nozzle For Enhanced Erosion Resistance

Erosion-induced failure of pulverized coal burner nozzles (PCBN) presents a significant challenge in pulverized coal-based thermal power plants. Investigations have identified multiple causative factors leading to the accelerated degradation and consequent reduced lifespan of PCBN. These factors include the erosive impact of solid fuel particles carried at high velocities and angles, as well as the high-temperature conditions within the combustion zone. To mitigate erosion, strategies often revolve around enhancing material resistance or optimizing aerodynamic profiles to minimize drag forces. This study employs Computational Fluid Dynamics (CFD) via the CFX code to model and analyze the erosion dynamics within PCBN. By adjusting the geometry of the inner plates within the PCBN, simulations indicated a notable improvement in erosion resistance. The optimized design achieved this by expanding the flow area between the innermost bifurcated plates without altering their angle, leading to a more uniform flow distribution and favorable velocity and pressure gradients. These modifications have the potential not only to prolong nozzle life but also to contribute to more efficient combustion in tangentially fired furnaces.

Study of the Injection of Secondary Air into the Intake Manifold of the Gas Turbine to Avoid the Compressor Surging Phenomenon

This paper presents part of the research on avoiding or reducing the surging effects that appear in the axial compressor intake manifold of a gas turbine. This research has led to an original solution validated by numerical simulations and experimental investigations. The increased amount of air suddenly required in the transient regime of the gas turbine is introduced into the intake manifold through slits arranged perpendicular to the direction of flow, on an aerodynamic profile at a certain angle to it and a certain distance from the minimum transversal section. The slits are arranged on the opposite sides of the gallery and connect with a transverse channel of the airfoil, in which there is air under pressure, from which the introduction of additional air is ordered. The numerical and experimental results extended to the influence of many geometric and mechanical parameters, proving that the proposed solution is as effective as possible compared to the classic ejector solution.

Inhalable porous particles as dual micro-nano carriers demonstrating efficient lung drug delivery for treatment of tuberculosis

Inhalation therapy treating severe infectious disease is among the more complex and emerging topics in controlled drug release. Micron-sized carriers are needed to deposit drugs into the lower airways, while nano-sized carriers are of preference for cell targeting. Here, we present a novel and versatile strategy using micron-sized spherical particles with an excellent aerodynamic profile that dissolve in the lung fluid to ultimately generate nanoparticles enabling to enhance both extra- and intra-cellular drug delivery (i.e., dual micro-nano inhalation strategy). The spherical particles are synthesised through the condensation of nano-sized amorphous silicon dioxide resulting in high surface area, disordered mesoporous silica particles (MSPs) with monodispersed size of 2.43 μm. Clofazimine (CLZ), a drug shown to be effective against multidrug-resistant tuberculosis, was encapsulated in the MSPs obtaining a dry powder formulation with high respirable fraction (F.P.F. <5 μm of 50%) without the need of additional excipients. DSC, XRPD, and Nitrogen adsorption-desorption indicate that the drug was fully amorphous when confined in the nano-sized pores (9–10 nm) of the MSPs (shelf-life of 20 months at 4 °C). Once deposited in the lung, the CLZ-MSPs exhibited a dual action. Firstly, the nanoconfinement within the MSPs enabled a drastic dissolution enhancement of CLZ in simulated lung fluid (i.e., 16-fold higher than the free drug), increasing mycobacterial killing than CLZ alone (p = 0.0262) and reaching concentrations above the minimum bactericidal concentration (MBC) against biofilms of M. tuberculosis (i.e., targeting extracellular bacteria). The released CLZ permeated but was highly retained in a Calu-3 respiratory epithelium model, suggesting a high local drug concentration within the lung tissue minimizing risk for systemic side effects. Secondly, the micron-sized drug carriers spontaneously dissolve in simulated lung fluid into nano-sized drug carriers (shown by Nano-FTIR), delivering high CLZ cargo inside macrophages and drastically decreasing the mycobacterial burden inside macrophages (i.e., targeting intracellular bacteria). Safety studies showed neither measurable toxicity on macrophages nor Calu-3 cells, nor impaired epithelial integrity. The dissolved MSPs also did not show haemolytic effect on human erythrocytes. In a nutshell, this study presents a low-cost, stable and non-invasive dried powder formulation based on a dual micro-nano carrier to efficiently deliver drug to the lungs overcoming technological and practical challenges for global healthcare.

Analysis of the aerodynamic performance of truck semi-trailers

In the last time, trucks have shown a very high interest in terms of their technical and fuel consumption performance. Prioritizing the phenomenon of having trucks that transport as much, as quickly and as economically as possible, this represent a new challenge for industry and engineering, which are in continuous development. The attempt to create a bridge as stable as possible between technical and consumer performance is supported by the multitude of areas that, based on studies and experimental trials, allow optimization without interfering, substantially, with the actual transport of the goods (loading capacities and transport). The main objective of this paper is to present the possibility of improving the aerodynamic performance of trucks, focusing on semi-trailers. For this study, a truck modelled at one to one scale was used, whose aerodynamic performance was verified in the virtual environment (CFD–Computational Fluid Dynamics); this environment has the possibility to test several geometric models without requiring the layout of a vehicle in physical form. To check the performance, a basic model was created, a conventional truck (tractor unit with semi-trailer), to which various semi-trailer modifications were made, such as: total and partial coverage of the side areas, idea to create a more aerodynamic profile of the semi-trailer in the back and the addition of fairings under the platform (underbody of the semi-trailer). The results describe the impact these elements have and allow the visualization of the possible future profile that is as aerodynamic as possible for semi-trailers (therefore also for trucks) from both theoretical and technical point of view. Through the proposed improvements the capacity and the transport of the goods is not affected, in a significant way so it can be said that there is the possibility of implementation in the industry.

Effects of Re on blade load temporal-spatial distribution and correlation with flow stability of transonic compressor under inlet distortion

Compressor blade operating conditions and aerodynamic load change periodically owing to inlet distortion. The effects of low Re are often unavoidable when the inlet distortion is encountered in real compressor operation. Blade load distribution and internal flow field are both affected by variations in Re. In this paper, the effects of Re on the blade load distribution patterns under 60° of total pressure distortion is investigated by numerical simulation. The distortion intensity has been set to 0.05, and four cases with Reynolds number index of 1, 0.3, 0.2 and 0.1 are chosen for further analysis. The findings demonstrate that the variation of Re affects the compressor flow field mainly by modifying the aerodynamic profile of the blade, which also results in the change of the temporal and spatial distribution of the aerodynamic load. Furthermore, the aerodynamic blade profile varies significantly by Reynolds number in different spanwise regions. The blade time constant decreases in the mid-span area, while it increases in the tip. This ultimately leads to a delay in the location of the tip maximum load, changing the starting position of the induced stall.

Mathematical models creation for calculating dimensional accuracy at the construction stages of an analytical standard using the chain method

The object of research is the process of forming a mathematical model (MM) for calculating accuracy at the stages of construction an analytical standard (AS) using the chain method, the application of which is shown on the example of an aviation object (AO). The analysis of the investigated AO, namely the helicopter stabilizer, was carried out using modern 3D scanners and the creation of its analytical portrait (AP). The problem is to create the most similar AP and compare it with AS, taking into account the results of the calculations. The following results were obtained: the AS was built and the AP of the stabilizer geometry was created, a comparative analysis of the AP and AS was carried out, and the results of the accuracy of the object geometry calculations were obtained. Aerodynamic calculations of stabilizer characteristics were also carried out, analysis of standardized aerodynamic profiles was carried out taking into account the accepted limitations for forming the stabilizer AS. The scientific and practical novelty of the obtained results is as follows: the created MM for calculating the accuracy of the dimensions of the unit contour using the chain method made it possible to estimate the tying errors that occur when using the loft-template method. This made it possible to choose equipment and software for construction the AS stabilizer. The selection of improved values of the object's aerodynamic characteristics made it possible to build an AS based on the standardized NACA 0012 profile. This can be used as an information basis for the organization of small-scale production of the object under study. That is, in general, the process of reverse engineering made it possible to conduct a detailed analysis of sections, aerodynamic characteristics and improve them for the future improved profile. This design approach provides wider opportunities, eliminates intermediate links and maintains high accuracy of object parameters during its manufacture, which is one of the main requirements in aircraft construction.

Validation of a two-fluid turbulence model in comsol multiphysics for the problem of flow around aerodynamic profiles

The article presents a study of a two-fluid turbulence model in the Comsol Multiphysics software package for the problem of a subsonic flow around the DSMA661 and NACA 4412 airfoils with angles of attack of 0 and 13.87 degrees, respectively. In this paper, the finite element method is used for the numerical implementation of the turbulence equations. To stabilize the discretized equations, stabilization by the Galerkin least squares method was used. The results obtained are compared with the results of other RANS, LES, DES models and experimental data. It is shown that in the case of continuous flow around the DSMA661 airfoil, the results of the two-fluid model are very close to the SST results and are in good agreement with the experimental data. When flowing around the NACA 4412 airfoil, flow separation occurs and a recirculation zone appears. It is shown that in such cases the two-fluid model gives more accurate results than other turbulence models. Implementation of the Comsol Multiphysics software package showed good convergence, stability, and high accuracy of the two-fluid turbulence model.

COMPUTATIONAL AND EXPERIMENTAL ANALYSIS OF A DIFFUSER THAT CONSTITUTES A CONCEPTUAL AND UNPRECEDENTED DAWT FOR URBAN APPLICATIONS

This article presents numerical analyses of diffusers formed by different curved aerodynamic profiles and high lift-to-drag ratio airfoils, with and without the use of a ring flap (flanged diffuser) applied externally at the diffuser exit. The objective is to identify the optimal geometry for the fabrication of a full-scale prototype of a DAWT (Diffuser-Augmented Wind Turbine), which is a conceptual and innovative design developed for urban and rural use. The diffuser aims to increase the mass flow rate through the turbine, allowing for greater power extraction at low wind speeds caused by surrounding buildings. The mass flow increment factor is used as a performance parameter for the diffuser and it is found to have an approximately linear growth with the sum of radial forces, which is related to the lift coefficient of the employed aerodynamic profile. Both the application of the ring flap and the axial length of the diffuser generate higher radial forces and increase the mass flow rate through the diffuser. The diffuser with the NACA 2421 airfoil profile demonstrated a mass flow increment of 1.42 in a configuration with a flap and a configuration without a flap but with a longer axial length. The flap causes higher drag force and higher standard deviation. Therefore, for the fabrication of the turbine prototype, a flanged diffuser with the NACA2421 airfoil profile is chosen. By comparing the numerical and experimental results of diffusers with the NACA2421 airfoil profile, it is concluded that the experimentally obtained velocity increment is 7% lower than the increment indicated by numerical simulations.

Numerical study of flow after NASA 4412 aerodynamic profile based on the SST turbulence model

This article investigates the application of the SST turbulence model within the Comsol Multiphysics platform to analyze subsonic airflow around a NACA4412 airfoil at an angle of attack of 13.87 degrees. The study employs the finite element method to solve the turbulence equations numerically, with stabilization achieved through the Galerkin least squares technique. Comparisons between the computational results and experimental data are conducted to assess the model's performance. The findings demonstrate favorable agreement between the SST turbulence model predictions and experimental observations, indicating promising convergence. This research contributes to the understanding of turbulence modeling in aerodynamics simulations and underscores the potential of the SST model in accurately capturing flow behavior around complex geometries like the NACA4412 airfoil.

Assessment of a virtual boundary concept for efficient modeling of turbine film cooling

Film cooling is one of key technologies advancing the performance of gas turbine engines, which is extensively applied in the hot turbine component for thermal protection by injecting cooling air from numerous film holes. To achieve an optimal film cooling scheme, many iterations of the position, the diameter, and the orientation of the holes through computation simulations are required to well fit the aerodynamic profiles of the turbine blades. However, a conventional computational simulation that resolves each individual hole and its coolant supply channel implies substantial costs of computation resources. In this study, a novel film cooling modeling method that uses a virtual boundary to represent film holes is assessed by comparing to the conventional computational simulation in two representative test cases, involving flat-plate and turbine endwall inlet film cooling. Relevant experiments are carried out to provide experimental data for verifying the approach at various coolant injection rates. Generally, the virtual boundary model produces rather equivalent results to those predicted by the conventional simulation method. Though coolant concentration downstream of the holes is over-estimated by the virtual boundary model due to neglected in-hole mixing, the overall flow fields and film cooling performance are well captured, showing the feasibility of the novel strategy in accurately modeling film cooling in a much more efficient way by saving computational efforts. This novel concept thereby allows designers to modify the film hole geometries independently of the blade geometry and thus, is helpful to accelerate the design process of a film-cooled turbine or to assess multiple film cooling configurations more quickly, as compared to a conventional computation simulation.