Aerodynamic Profile Research Articles

Numerical Investigation on Intermittent Maximum Ice Accretion and Aerodynamic Performances of RG-15 Aerofoil at Low Reynolds Number

Ice accretion is inevitable on fix-wing UAVs (unmanned aerial vehicles) when they are applied to surveillance and mapping over colder climates and arctic regions. Subsequent aerodynamic profile changes have caused the current interest in the better prediction of the effect of icing shapes/sizes/distribution patterns on the aerodynamic performances of an aircraft. This study employs a numerical model which investigates the RG-15 aerofoil’s response to various icing scenarios at a Reynolds number of Re=2×105. Under icing conditions, compared to a clean aerofoil, a reduction in the lift coefficient and an increase in the drag coefficient are observed. Lower temperatures and reduced liquid water content lead to a decrease in the maximum thickness of ice accretion on the RG-15 aerofoil. Particularly noteworthy is the 10.85% reduction in the lift coefficient at a 10° angle of attack, which is in the icing condition at −10 °C with a mean volume diameter of 15 μm. Power consumption increases in the range of 0.46% to 26.5% under various icing conditions, showing synchronization with the rise in drag coefficient. This study underscores the need for future research to investigate various cloud conditions comprehensively and deeply in the context of aerofoil icing.

Enhancing Cutting Efficiency and Minimizing Forces for Nomex Honeycomb Core Using Grey Relational Analysis and Desirability Function Analysis.

Nomex Honeycomb core is the foundational building block for manufacturing aerospace composite components. Its usage requires machining honeycomb in complex aerodynamic profiles where the quality of the core is governed by accuracy and precision of cut profiles. The assessment of accuracy and precision is directly related to forces induced in the cutting tool and cutting efficiency. These two parameters form the basis of a multi-objective function that this paper aims to optimize for the milling operation. The parameter of depth of cut considered in this paper has not been analyzed in a multi-objective optimization study of the Nomex Honeycomb core previously. A Taguchi-based array of Design of Experiments followed by Analysis of Variance and correlation analysis is utilised. The results indicate that the most significant factor is the feed rate, with a percentage contribution of 72% for the cutting forces and depth of cut, with a percentage contribution of 85% in the case of cutting efficiency. The two parameters are optimized using Desirability Function Analysis and Grey Relational Analysis. The results are validated through experimental runs with an error within 5% of the statistical predictions, with the percentage improvement in cutting forces for optimum runs as compared to the worst experimental run at 47.8%. The percentage improvement in cutting efficiency likewise is 11%.

Deep neural network modeling for CFD simulation of drone bioinspired morphing wings

In this paper we present a deep neural network modelling using Computational Fluid Dynamics (CFD) simulations data in order to optimize control of bioinspired morphing wings of a drone. Drones flight needs to consider variation in aerodynamic conditions that cannot all be optimized using a fixed aerodynamic profile. Nature solves this issue as birds are changing continuously the shape of their wings depending of the aerodynamic current requirements. One important issue for fixed wing drone is the landing as it is unable to control and most of the time consequences are some damages at the nose. An optimized shape of the wing at landing will avoid this situation. Another issue is that wings with a maximum surface are sensitive to stronger head winds; while wings with a small surface allowing the drone to fly faster. A wing with a morphing surface could adapt its aerial surface to optimize aerodynamic performance to specific flight situations. A morphing wing needs to be controlled in an optimized manner taking into account current aerodynamics parameters. Predicting optimized positions of the wing needs to consider (CFD) prior simulation parameters. The scenarios for flight require an important number of CFD simulation to address different conditions and geometric shapes. We compare in this paper neural network architecture suitable to predict wing shape according to current conditions. Deep neural network (DNN) is trained using data resulted out of CFD simulations to estimate flight conditions.

SIMULATION OF THE AUTOMATIC CONTROL SYSTEM OF A HORIZONTAL-AXIAL WIND POWER PLANT

We considered the results of modelling the operating modes of an electric power generation system of a horizontal-axial wind turbine. The system consist of an aerodynamic blades of a wind wheel connected by an elastic shaft to a generator through a multiplier. Engineering part of the automatic control system (ACS) is the mechanism of rotation of the blades relative to the angle of wind flow. A method for optimizing the main parameters: geometric, dynamic and ACS coefficients is proposed. The method allows a comprehensive assessment of the operation of wind turbines. The value of the average annual electricity generation was used as an optimization criterion. As a result, a deep optimization of the adjustment depth coefficient was carried out. Secondly, we investigated the system in dynamics. A stochastic wind model was used as a disturbing effect. We constructed the system by mathematic simulation methods. As a reference control algorithm, a direct linear dependence of the angular velocity of the turbine rotation on the wind speed with restrictions on the minimum and maximum values was used. Also we described the mathematical model of system and the initial results of the theoretical calculations of algorithms for controlling. The versatility of the calculation system makes it possible to use any aerodynamic profiles of the blades in its composition. The characteristics of aerodynamic moments for the calculation of force moments are obtained by converting Lilienthal curves as initial data for the considered aerodynamic profiles.

Modelling dynamic pantograph loads with combined numerical analysis

Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric trains. Changing heights of overhead lines to accommodate level crossings, overbridges, and tunnels pose significant challenges in maintaining consistent current collection performance as the pantograph aerodynamic profile, and thus aerodynamic load changes significantly with operational height. This research aims to analyse the global flow characteristics and aerodynamic forces acting on individual components of an HSX pantograph operating in different configurations and orientations, such that the results can be combined with multibody simulations to obtain accurate dynamic insight into contact forces. Specifically, computational fluid dynamics simulations are used to investigate the pantograph component loads in a representative setting, such as that of the recessed cavity on a Class 800 train. From an aerodynamic perspective, this study indicates that the total drag force acting on non-fixed components of the pantograph is larger for the knuckle-leading orientation rather than the knuckle-trailing, although the difference between the two is found to reduce with increasing pantograph extension. Combining the aerodynamic loads acting on individual components with multibody tools allows for realistic dynamic insight into the pantograph behaviour. The results obtained show how considering aerodynamic forces enhance the realism of the models, leading to behaviour of the pantograph–catenary contact forces closely matching that seen in experimental tests.

The effect of swallow-shaped bionic ribs on the thermal-hydraulic performance of heat exchanger tubes

This paper combines the bionic structure and multi-vortex longitudinal swirl to enhance the heat transfer in the heat exchanger tube while reducing the increase in flow resistance. The design of the enhanced tube with swallow-shaped bionic ribs is inspired by the aerodynamic profile of the swallow flight process to improve the comprehensive performance. The SST k-ω model is selected for numerical simulation. The study of the effect of TCR (triangular concave rib) bionic rib and TVR (triangular convex rib) bionic rib on the flow field characteristics and thermal–hydraulic performance, and the analysis of the effect of pitch ratio (P*) on the thermal–hydraulic performance of TCR tube. The results show that both types of bionic ribs promote the formation and development of multi-vortex longitudinal swirl and transverse swirl in the tube, strengthening the mixing of hot and cold fluids in the tube, improving the synergy of velocity and temperature fields, and making the temperature distribution in the tube more uniform. When P* = 0.75, Nusselt number of the TCR and TVR enhanced tubes is increased by 52.3 %–65.8 % and 43.3 %–57.9 %, respectively, and friction factor is increased by 92.7 %–202.3 % and 78.7 %–263.9 %, respectively, over the smooth tubes. The effect of P* on the thermal–hydraulic performance of the TCR tube is studied, and the PEC value increases as P* decreases. Compared to smooth tubes, TCR enhanced tubes have improved Nusselt number by 26.4 %–95.6 %, friction factor by 50.4 %-345.8 %, and PEC can reach 1.335 when the pitch ratio P* = 0.5. Consequently, the enhanced tube obtains the good comprehensive performance.

Chitosan-based pulmonary particulate systems for anticancer and antiviral drug carriers: A promising delivery for COVID-19 vaccines

Chitosan (CHI) has antimicrobial and anticancer characteristics in addition to being biodegradable and biocompatible as a polymer. It has recently attracted a lot of attention as a potential drug carrier framework material for pulmonary therapeutic transport, particularly in the context of treating infectious diseases and cancer. CHI mucoadhesive, permeation-enhancing, and site- and cell-specific properties all play a key role in the therapeutic carrier's efficacy in the pulmonary circulation. Numerous microencapsulation and micro-nanomixing techniques have been developed to provide nanocarriers with the proper aerodynamic profile for effective pulmonary aerosolization and inhalation. Acute respiratory distress syndrome (ARDS) and cancer are the outcomes of a subsequent infection with COVID-19. The effectiveness of anti-CoV and anticancer treatments using CHI and its derivatives varies with molecular weight, substituent type, and degree of substitution. From the viewpoint of drug delivery (DD), in addition to its therapeutic performance, CHI is anticipated to attract more attention throughout the coming decade.

Influence of Design Parameters on Mechanical Behavior of Multi-Bolt, Countersunk C/SiC Composite Joint Structure.

Aerospace vehicle connection constructions are in urgent need of joint structures with excellent aerodynamic profiles and environmental adaptability. To address issues such as poor aerodynamic profile, material thermal expansion coefficient mismatch, and limited joint structure evaluation indexes, a multi-bolt, countersunk C/SiC composite joint structure is presented in this study. The development of a 3D Hashin progressive damage model and its dedicated solver code is presented. The validity of the model is confirmed by comparing simulation results with experimental data. Three evaluation indexes are proposed, peak load, weight increment efficiency, and bolt load distribution, to thoroughly evaluate the mechanical performance of multi-bolt, countersunk C/SiC composite joint structures. Using the proposed model and evaluation indices, we evaluate sixteen different designs of multi-bolt, countersunk C/SiC composite joint structures and analyze how design parameters affect their mechanical properties and damage patterns. The results show that the best mechanical properties of the joint structure are achieved when the ratio of bolt pitch to through hole diameter is 3, the ratio of bolt spacing between columns to through hole diameter is 4, the ratio of the distance between the free edge of the substrate to through hole diameter is 1.5, the ratio of through hole diameter to specimen thickness is 1.7, and the ratio of the distance between the edge of the substrate to through hole diameter is 1.5.

Investigating the aerodynamic effect of rooftop cargo compartment – a case of modified intercity bus

Buses are one mode of mass transportation but they are inefficient in terms of fuel consumption and ergonomically poor when loaded. Thus to decrease the fuel consumption, an improvement on the aerodynamic shape of the bus is required. This paper mainly focused on locally modified ISUZU buses which are serving as an intercity bus in Ethiopia. These buses are inefficient in terms of fuel consumption because of their body design and other add-on devices. One of the add-on devices which spoil the aerodynamic profile of this bus is the luggage loaded on the roof rack. Therefore, in this paper aerodynamically efficient rooftop luggage compartment is designed for these buses. The performance test is carried out for a scaled-down ISUZU bus model numerically using ANSYS Fluent CFD software and experimentally using wind tunnel testing. The numerical results are validated by an experimental test which is carried out using HM 170 open wind tunnel set-up. According to the numerical result, the modified bus reduced the drag coefficient by 34%, 34.5% and 34%, when compared to the clean roof baseline bus, the baseline bus with roof rack and the loaded baseline bus respectively. Similarly, the drag force is reduced by 12%, 14% and 32% respectively. In addition, the fuel consumption is reduced by 2.15 l h −1, 4.17 l h −1 and 7.24 l h −1 respectively. It is also found that the numerical results are in good agreement with the experimental results. Overall, the modified bus is found to be more fuel saving and ergonomically better design.

Optimization of Aerodynamic Profile of Ground Vehicle

In this paper, the aerodynamic profiles of different types of ground vehicles, racing cars, freight cars, and bullet trains, as well as their shape design and use, will be introduced and discussed by using the equation . The methods adopted by predecessors o find the best aerodynamic profile for these vehicles are also introduced. The conclusion is that the best aerodynamic profile for race cars is equipped with spoilers and a relatively great slicing angle at the rear bottom of the vehicle. Furthermore, diffusers are optional but can also decrease the drag force. For lorries, the best modification is completely sealing the gap between the trailer and undercarriage with a dynamic rear flap. If possible, add roof tapering on the trailer, but it will reduce the amount of cargo shipped. For a bullet train, the longer the nose of the train is, the less drag it will experience.

Novel design of variable Mach number nozzle operated by a single jack

The increasing demand for the wide-range aircraft technique requires the ground test facilities with continuous variation of the Mach number. Owing to the rigorous aerodynamic foundation and simple operation, the single-jack flexible nozzle is widely used. However, there are still some problems in the original single-jack flexible nozzle, such as low Mach number and insufficient flow uniformity. This paper presents a novel design of the single-jack flexible nozzle with high flow uniformity and continuous variable Mach number, adopting flow field inverse design and elasticity inverse design. The new nozzle adopts a three-order transonic asymptotic solution and a B-spline axial velocity distribution, designed by the method of characteristics. By comparing with the original nozzle, the new nozzle no longer requires the conical flow assumption, and the flow fields are more uniform. Another improvement is the continuous contour curvature to ensure the coincidence of the aerodynamic profile and the elastic profile, avoiding the negative Mach waves generated by the curvature discontinuity. In addition, the new nozzle has the advantage of two Mach number design points. Similar to the squeeze theorem, the flow fields are uniform at the non-design points between two design points. The numerical results show that the new nozzle eliminates the Mach waves at different Mach number cases. Within the design range of Mach 2.0–4.0, the flow angle's maximum deviations do not exceed 0.2°, and the average deviations do not exceed 0.1°, meeting the national standard of 0.3°. The Mach number's maximum deviations are around 0.5% of Ma¯, the average deviations are less than 0.2% of Ma¯, and the standard deviations meet the national advanced standard. Even at Mach 1.5 and Mach 4.5 outside the design range, the new nozzle still performs well. The evaluation results validate the feasibility of the novel design, supporting the future construction of the variable Mach number facility.

Structural optimisation of H-Rotor wind turbine blade based on one-way Fluid Structure Interaction approach

The paper aims to present structural topology optimisation of the structural topology of the H-Rotor wind turbine combined with the one-way Fluid Structure Interaction (FSI) approach. The developed methodology couples the set of Unsteady Reynolds Averaged Navier–Stokes Equations (URANS) with the steady state linear elasticity equations and density based topology optimisation method. This approach allowed us to reduce the mass of the blades with respect to the maximum stress and deformation limits. The results obtained provide detailed information on the unsteady flow fields around the operating wind turbine, as well as optimised topology of the blade interior without affecting the external aerodynamic profile. The load of pressure profile from the CFD simulation was implemented at the point of rotation at which the force values observed on the blade surface were the highest. The centrifugal force was considered in the structural model. Computations were carried out for wind speed equal to 30 m/s and rotational velocity equal to 90 rad/s. The turbine operating parameters were chosen to represent extreme operating conditions. The results obtained showed that the blade mass, made of the same material, can be easily reduced by around 60% with the reduction of the observed stress values and deformation.

Design and Analysis of Multi-Layer Patched Efficient Antenna for 28-GHz Applications

Microstrip antennas possess a compact form factor, exhibit a low profile, and demonstrate a lightweight nature, thereby enabling their suitability for deployment on both planar and non-planar surfaces. When the framework is installed, it requires a comparatively small amount of space. The production of printed circuits has become a facile and inexpensive process owing to advancements in contemporary technology. Antennas with a low profile are often required owing to space, weight, cost, performance, simplicity of installation, and aerodynamic profile in powerful planes, spaceships, satellites, and rocket operations. Many other applications, not only mobile radio and wireless communications, have comparable requirements. Microstrip antennas are a useful tool for accomplishing this goal. A proposal has been put forth to utilize a patch antenna for 5G cellular connectivity at 28 GHz, with the aim of generating robust beams on the azimuthal plane. The antenna proposed in this study exhibits a radiation efficiency of 93.46 percent and a total efficiency of 92.80 percent, as demonstrated through simulations. This study showcases the feasibility of producing millimeter-wave antennas operating at 28 GHz through the utilization of cost-effective additive manufacturing techniques. The simulation of all outcomes is conducted through the utilization of the CST Microwave Studio.

COMPUTATION OF FLOW ABOUT AIRFOILS – COMPARISON OF PANEL METHOD AND CFD METHOD

The aerodynamic study of an airfoil is fundamental to analyze the behavior and define geometrical characteristics of a wing for prescribed flight conditions. Based on analyzes and simulations we are able to define the variables for aerodynamic design of an aircraft. The unmanned aerial vehicle (UAV) designed for SAE Aerodesign competition use high lift airfoils for low Reynolds number flow. The viscous or inviscid flow about airfoils can be computed using different methodologies, such as panel method or finite volume method. The main objective of this work is to compute and compare the lift and drag coefficients as well as pressure distributions in the contour of airfoils calculating the inviscid and viscous flow, using a panel method and a finite volume method. For the numerical analysis, high lift airfoils of families NACA 4, EPPLER, GOE, CH and SELIG were selected. These airfoils have very good aerodynamic efficiency with high ratio between the lift and drag coefficients. These profiles are highlighted by its high mean-line curvature and are used at low speeds, being indicated for the SAE Aerodesign competition aircrafts. The criterion used to choose the airfoil was the highest lift coefficient generated in relation to its maximum stall angle, at a number of Reynolds of cruising flight speed, that is close to the transition from laminar boundary layer to turbulent boundary layer. The panel method analysis was performed using the XFRL5 software that uses XFOIL as source code. In the finite volume method, the Fluent code of ANSYS was used. Different types of meshes, structured and unstructured, are compared and quality parameters of mesh cells are analyzed and presented. The pressure distributions and the lift and drag coefficient curves, for the selected aerodynamic profile, calculated using panel method and finite volume method, are also presented and compared.

Unsteady reduced order model with neural networks and flight-physics-based regularization for aerodynamic applications

Numerical simulation of unsteady fluid flow plays an important role in several areas of the aeronautical industry. Since high-fidelity computational fluid dynamics simulations could be prohibitive in terms of computational cost, data-driven reduced order models become a suitable alternative for efficiently predicting flow variables as long as the accuracy of such models is comparable to that obtained by the full order model counterpart. This is especially important for iterative design purposes, where a few target variables must be evaluated on a large number of possible parameters. Therefore, we propose a neural network based methodology to develop an unsteady reduced order model of the subsonic/transonic flow field on 2D aerodynamic profiles trained on high-fidelity computational fluid dynamics data. For the purpose of dimensionality reduction, either proper-orthogonal decomposition or autoencoders are employed. For the regression task, a gated recurrent unit neural network is used to map an unsteady Schroeder multi-sine signal of angle of attack along with its first and second time-derivatives to the solution of surface variables, such as coefficients of pressure and friction. In order to shed light on the inner workings of data-driven methods so it could be employed in the aircraft design process, we introduce a flight-physics-based regularization term to incorporate information about the calculation of integral coefficients, like drag and lift, into the machine learning training workflow. Using our method, airfoil flow variables of interest can be predicted at a fraction of the cost of classical methods without any considerable accuracy loss. We also provide a comparison between reduction methods and we show evidence that supports the use of the proposed flight-physics-based regularization for building unsteady reduced order models based on machine learning.

Study of fluid-dynamic behavior in a convergent–divergent nozzle by shape optimization using evolutionary strategies algorithms

The performance and thrust of a rocket propulsion system are based mainly on the utilization of the enthalpy of the propellants in the combustion chamber. This accumulated energy is transformed into kinetic energy by the expansion and acceleration of the gases produced by the chemical reaction of combustion, using a device known as a nozzle. This project studies the aerodynamic profile to trace the wall contour of a C-D nozzle based on the technical operating conditions of a rocket engine. The wall contour is traced using different design methods and, for each nozzle section, the behavior of the fluid-thermal properties of the flow field along the flow trajectory of the aerospace nozzle is analyzed. This is necessary because, in each wall contour suggested by the models, the angle of inclination of the curvature is different (the concavity or shape of the curve changes) and, therefore, the physical magnitudes of the properties vary according to the contour. To determine which design complies with the concept that processes occurring within a nozzle are isentropic and reversible, a statistical analysis of data dispersion is performed to choose the design with the lowest energy losses as a function of friction and entropy. An unconstrained optimization is applied to maximize or minimize the cross-sectional area of the nozzle geometric profile through genetic algorithms. To corroborate the nozzle wall contour and the design methodology used, a simulation is performed to evaluate the similarities between the operating characteristics and Mach number with another nozzle of a J-2 rocket engine.

Bio-Inspired Deformable Propeller Concept for Smooth Human-UAV Interaction and Efficient Thrust Generation

This letter presents a novel deformable propeller concept, 3D-printed in flexible thermoplastic polyurethane, which stores impact energy in the form of elastic energy for smooth collisions, reducing risk in human-UAV interactions. However, such a design experiences elastic deformations when exposed to aerodynamic and centrifugal loads. The most relevant occur in the 3-5 krpm range. At higher speeds, the centrifugal force is dominant and the propeller becomes quite stiff. This work provides an investigation of the propeller deformation angles (which ultimately alter the aerodynamic profile and limit thrust generation) based on Fluid-Structure Interaction (FSI) simulations. These results are leveraged to introduce two complementary solutions: deformation reduction oriented internal fiber distributions, inspired by the ultra-efficient dragonfly wings (I); anticipatory designs which pre-modify pitch and roll angles based on simulation results to ensure optimal performance at the target rotational velocity (II). This letter offers a multi-configuration analysis, yielding an easy to manufacture propeller with a specific design methodology which results in increased efficiency and reduced impact recovery time. This work presents collision tests with various objects, as well as a proof of concept for its flight capabilities in a conventional quadrotor, including physical interaction with humans. These findings are valuable for the development of collision control strategies for UAVs.

New Viewpoint on the Mechanism of Laminar Separation Flutter

At transitional Reynolds numbers, an elastically supported airfoil oscillating in pitch can undergo laminar separation flutter (LSF), which is characterized by self-sustained small-amplitude oscillations. To gain insight into the mechanism of LSF, we conduct wind tunnel tests for to investigate the LSF response of a freely rotating NACA0015 airfoil with various structural natural frequencies and positions of the elastic axis. The experimental results show that the dominant mode of flow around the NACA0015 airfoil abruptly changes at , resulting in a change in the trend of LSF response. Then, an aeroelastic model is constructed to explain how the instability of LSF arises. This model can accurately predict the LSF frequency of airfoils with various structural natural frequencies. Moreover, based on the aeroelastic model, we perform linear stability analysis on the aeroelastic system and propose the instability criterion for LSF as . This instability criterion is identical to that for rotational galloping of square cylinder, indicating that LSF and rotational galloping of square cylinder are essentially the same aeroelastic phenomenon that appears in different aerodynamic profiles. This finding identifies the underlying cause for the remarkable similarities between the two phenomena.

Interactive design of 2D car profiles with aerodynamic feedback

AbstractThe design of car shapes requires a delicate balance between aesthetic and performance. While fluid simulation provides the means to evaluate the aerodynamic performance of a given shape, its computational cost hinders its usage during the early explorative phases of design, when aesthetic is decided upon. We present an interactive system to assist designers in creating aerodynamic car profiles. Our system relies on a neural surrogate model to predict fluid flow around car shapes, providing fluid visualization and shape optimization feedback to designers as soon as they sketch a car profile. Compared to prior work that focused on time‐averaged fluid flows, we describe how to train our model on instantaneous, synchronized observations extracted from multiple pre‐computed simulations, such that we can visualize and optimize for dynamic flow features, such as vortices. Furthermore, we architectured our model to support gradient‐based shape optimization within a learned latent space of car profiles. In addition to regularizing the optimization process, this latent space and an associated encoder‐decoder allows us to input and output car profiles in a bitmap form, without any explicit parameterization of the car boundary. Finally, we designed our model to support pointwise queries of fluid properties around car shapes, allowing us to adapt computational cost to application needs. As an illustration, we only query our model along streamlines for flow visualization, we query it in the vicinity of the car for drag optimization, and we query it behind the car for vortex attenuation.

Numerical validation of aerodynamic behavior for UWA profile at low Reynolds numbers

This research presents the results of the UWA profile simulation, which is compared to profiles E387 and UMY02-T01-26 that maximizes the lift-to-drag coefficient ratio. The obtained results of the lift/drag ratio of the aerodynamic profile uniformly increase under different leading angles when compared to profiles E387 and UMY02-T01-26 in 30% ~ 40% for Re = 2 x 105. After comparison, it was determined that the profile created is adequate for wind turbines at low Reynolds numbers due to their better lift-to-drag ratio.