Aerodynamic Issues Research Articles

Application of artificial intelligence in turbomachinery aerodynamics: progresses and challenges

Turbomachinery plays a vital role in energy conversion systems, with aerodynamic issues being integral to its entire lifecycle, spanning the period of design, validation, and maintenance. Conventionally, the reliance on skilled aerodynamic engineers has been pivotal in the successful development of turbomachines. However, in the current era of burgeoning artificial intelligence (AI) technology, researchers are increasingly turning to AI to replace human expertise and decision-making in these aerodynamic issues and to solve previously intractable aerodynamic problems. This paper presents a systematic literature review of the latest advancements in applying AI to turbomachinery aerodynamics, encompassing the design, validation, and maintenance of compressors and turbines. It underscores how AI is revolutionizing the research paradigm of turbomachinery aerodynamics. AI’s powerful learning capability facilitates more precise and convenient aerodynamic analyses and inspires innovative aerodynamic design ideas that go beyond the capabilities of classical design techniques. Additionally, AI’s autonomous decision-making capability can be employed for aerodynamic optimization and active flow control of turbomachines, generating optimal aerodynamic solutions and complex control strategies that surpass human brains. As a main contribution, we provide a detailed exposition of the future intelligent turbomachinery research and development (R &D) system, along with highlighting potential challenges such as physics embedding, interactive 3D design optimization, and real-time prognoses. It is anticipated that harnessing AI’s full potential will lead to a comprehensive AI-based turbomachinery R &D system in the future.

Model Free Adaptive Iterative Learning Control Based Fault-Tolerant Control for Subway Train With Speed Sensor Fault and Over-Speed Protection

A model free adaptive iterative learning control based fault-tolerant control (MFAILC-FTC) scheme for subway train speed tracking with speed sensor fault and over-speed protection is proposed. Firstly, the train dynamics is transformed into a compact form dynamic linearization (CFDL) data model by applying the concept of pseudo-partial derivative (PPD). If speed sensor fault occurs, the fault function is approximated by the trained RBFNNs under normal condition and the output data of the train system with fault, which serves as a compensation for the proposed MFAILC-FTC scheme. Then, over-speed protection mechanism is developed to ensure that the train operates within safe speed range. Furthermore, the constraint on traction/braking force is also taken into account. Through rigorous mathematical analysis, it is proved that the proposed MFAILC-FTC method with over-speed protection mechanism can ensure the train speed tracking error converges along the iteration axis, which implies the train operates safely and reliably. Finally, the simulation results further demonstrate the effectiveness of the proposed algorithm. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Subway train as a practical engineering system with short distance between two stations, starts and stops frequently, has the outstanding repetitive operation pattern, and it is unavoidable subject to speed sensor fault, aerodynamic issues, constraint on output speed and traction/braking force. Nevertheless, few works have considered these factors simultaneously, and a lot of data contain valuable operation information are generated during the train operation, this motives the work of this note. On account of the repetitive operation features of subway trains, the control schemes of speed trajectory tracking are handled under MFAILC framework, which is a pure data-driven model free control methodology. By constructing the RBFNNs-based fault function estimation mechanism, a robust compensation term is designed in the fault-tolerant controller. Taking the safe operation of subway trains into account, an over-speed protection term with trigger mechanism is added to the fault-tolerant controller. To further enhance the application, the constraint on traction/braking force is addressed as well. Without requirement of the train dynamics model, the theoretical analyses and simulation results have confirmed the effectiveness and the feasibility of the proposed data-driven control approach. In the future work, we will focus on verifying the proposed control strategy and addressing some other practical problems, for instance, the energy-efficiency and exogenous disturbances during the train operation.

Moving model experimental analysis of the slipstream produced by a simplistic square-back high-speed train

High-speed trains (HSTs) are being buffeted by accelerating running speed, and with that comes the aerodynamic issues. The slipstream is related to the train aerodynamic characteristics and of importance to the safety of surrounding people and structures. In this study, the ensemble-averaged and instantaneous characteristics of the slipstream of a simplistic high-speed train model with a square-back were experimentally investigated using a novel moving model rig. The present investigation indicates that the double-line substructure causes obvious asymmetry in the slipstream even at locations apart from the bridge surface with a large distance. The square-back of the HST attenuates its slipstream significantly relative to that with a streamlined tail. Besides, the decaying rate of the slipstream is higher in the wake of a square-back HST. The presents results suggest that the trailing vortices downstream of the square-back HST are substantially suppressed.

Numerical investigation of the slipstream characteristics of a maglev train in a tunnel

High-speed maglev trains operate at higher speeds than conventional high-speed trains. This has implications on intensified aerodynamic issues, such as the transition between open air running and entering into a tunnel. In this paper, numerical simulation of a maglev train entering a tunnel is carried out using IDDES methods (based on SST k-omega model) to analyze the changing slipstream. The peaks and fluctuations of the slipstream are analyzed, together with the transient wake characteristics and TKE (turbulent kinetic energy) distributions. The influence of train nose length on the slipstream and its associated characteristics inside tunnels is also investigated in this paper. It was found that as the maglev train enters the tunnel, the wake slipstream at measuring points close to tunnel entrance increases significantly then decreases slightly with the increase of distance to tunnel entrance. Overall, the fluctuation and magnitude of slipstream inside tunnel is larger than that on open line, more specifically, the maximum TKE generated inside tunnel is. 7.62% larger than that on the open line at contour X = 3 H behind the train tail. Besides it takes longer time for the slipstream inside tunnel to return to the initial condition. These phenomena could be explained by that the scale of vortex structure formed behind the train tail is larger, the developing distance of the wake vortices in the streamwise direction is longer and the TKE generated is more significant inside tunnel. It was also found that increasing the nose length could effectively decrease the spatial scale and TKE of the wake vortices, which resulted on reducing the peak and pulsation of wake slipstream. Comparing to that of 5.4 m, the peak of the wake slipstream of the maglev trains with the 7.4 m and 9.4 m nose lengths at Y = 0.235 m(0.385) is reduced by approximately 23.7%(58%) and 35.9%(82.2%) on open field, and by about 3.6%(4.7%) and 14%(18.5%) inside tunnel. Besides, the maximum TKE at contour X = 2H/3H/5H behind the train tail decreases about 14.4%/10.7%/11.3% and 51%/31.5%/18% as the nose length increase to 7.4 m and 9.4 m respectively.

Computational Fluid Dynamics (CFD) Analysis of 3D Car Model to Understanding Key Aerodynamic Issues and Their Interaction with Other Motorsport &amp; Automotive Vehicle System

Abstract: Growing population of vehicles is one the biggest global concern and it led to traffic problems and creates congestion. People are not getting place to park their vehicles. Travel by car for shorter distance also stressful and time consuming because they have to face road traffic and usually cars are big at size so, to travel by car on road need more spacious and traffic free roads. that’s why some manufacturers start designing &amp; manufacturing One seater vehicle which can easily transportable and create less congestion. If a single person wants to ride somewhere then he doesn’t have to take large car for one person, He can use single seater vehicle. In this assignment I have Designed and Tested a single seater electric vehicle which can easily transportable, compact and personal commuter vehicle (PMV). Keywords: CFD analysis, Aerodynamics analysis, automotive vehicle system, 3D modelling, pressure plot, performance optimization, vehicle aerodynamics.

Insight into the factors affecting the safety of take-off and landing of the ship-borne helicopter

Despite the important role and highly frequent appearance of the helicopter in modern ship operations, the flight mission with take-off and landing of helicopters to ships, especially ships with small-sized decks, could be very challenging and potentially hazardous. Many researches on ship-helicopter dynamic interface (DI) have been conducted, and significant progress has been made. In this paper, a comprehensive and systematical review of the factors affecting the flying qualities of ship-borne helicopter and pilot workload during taking off and landing is derived from these efforts to date. The factors from two aspects, including the ship environment and the pilot-helicopter interface, are covered to address how these factors affect the helicopter handling qualities and pilot workload, primarily focusing on aerodynamic issues. The insight into these factors is not only of great significance for conducting take-off and landing tasks safely but also helpful to establish suitable fidelity criteria and guidelines for the modelling and simulation of the ship-helicopter DI environment.

Material behaviour in micropolar fluid of Brownian motion over a stretchable disk with application of thermophoretic forces and diffusion-thermo

To study the material behavior of axisymmetric flow in micropolar fluid for heat and mass exchange over a stretchable disk placed in porous medium taking into account the effect of heat generation, diffusion thermo, Brownian motion and thermophoretic effect. A suitable similarity transformations is adapted to convert the governing PDEs to non-dimensional form. A well-tested, numerically stable MATLAB code in connection with Bvp4c is employed for the conservation of equations. The noticeable features of the relevant parameters on micropolar fluid flow for axial velocity, radial velocity, micro-rotation, temperature and species concentrations profiles are accentuated on the plots using MATLAB. It is found that angular velocity is enhanced for augmented values of micropolar parameter. Moreover, due the effect of thermophoretic force, the thickness of thermal and concentration boundary layer are enhanced. In addition, thermal diffusion becomes more due to the increase in the vortex viscosity of the fluid, and an amplified thermal and molar concentration boundary layer thicknesses can be found. This study incorporates numerous engineering applications on rotating machineries, spin-coating, centrifugal pumps, computer storage devices, chemical engineering and different aerodynamic issues. Also, this analysis signifies great impact on biomechanics and stenosis related issue in medical sciences.

Multi-objective aerodynamic optimization of high-speed train heads based on the PDE parametric modeling

With the increasing running speed, the aerodynamic issues of high-speed trains are being raised and impact the running stability and energy efficiency. The optimization design of the head shape is significantly important in improving the aerodynamic performance of high-speed trains. Existing aerodynamic optimization methods are limited by the parametric modeling methods of train heads which are unable to accurately and completely parameterize both global shapes and local details. Due to this reason, they cannot optimize both global and local shapes of train heads. In order to tackle this problem, we propose a novel multi-objective aerodynamic optimization method of high-speed train heads based on the partial differential equation (PDE) parametric modeling. With this method, the half of a train head is parameterized with 17 PDE surface patches which describe global shapes and local details and keep the surface smooth. We take the aerodynamic drag and lift as optimization objectives; divide the optimization design process into two stages: global optimization and local optimization; and develop global and local optimization methods, respectively. In the first stage, the non-dominated sorting genetic algorithm (NSGA-II) is adopted to obtain the framework of the train head with an optimized global shape. In the second stage, Latin hypercube sampling (LHS) is applied in the local shape optimization of the PDE surface patches determined by the optimized framework to improve local details. The effectiveness of our proposed method is demonstrated by better aerodynamic performance achieved from the optimization solutions in global and local optimization stages in comparison with the original high-speed train head.

МЕТОД ВИБОРУ СКЛАДУ І РЕЖИМУ РОБОТИ СИЛОВОЇ УСТАНОВКИ, РЕЖИМУ РОБОТИ ДЛЯ ЛІТАЛЬНОГО АПАРАТА З НАДЗВУКОВОЮ КРЕЙСЕРСЬКОЮ ШВИДКІСТЮ

The power plant (PP) of a supersonic aircraft is a system that is part of a more complex system - the aircraft. Therefore, the efficiency of the aircraft significantly depends on the PP composition and its operating mode. Choice of composition and operation mode of PP is a part of the complex integrated variational optimization task, where parameters of flight profile, aircraft and PP are varied. Due to the complexity of the task in complete formulation, it is usually simplified. Typically, for the supersonic aircraft, the flight profile, flight mode for the cruising segment, payload, geometric shape and aerodynamic coefficients of the aircraft are specified. The dimensions and weight of the aircraft, as well as the parameters of the PP are varied. The required fuel and PP mass are determined. The minimum takeoff gross weight of the aircraft is a criterion of choosing the composition of the PP. A main disadvantage of this method is the insufficiently successful decomposition of the complex problem. In particular, the issues of aircraft aerodynamics, aircraft design and the theory of air-breathing engines are being comprehensively resolved, which complicates the task both in scientific and organizational terms - it is difficult to set design tasks for specialized organizations. Another decomposition method based on decomposing a complex problem into its components is proposed. The first component is the problem of choosing the composition and parameters of the PP, for the flight profile, mass, geometric and aerodynamic characteristics of the aircraft which are set; the second one is the problem of choosing the parameters of the aircraft, for the flight profile and the geometric shape of the aircraft that are set by varying the size and mass of the aircraft; the third one is the problem of choosing the parameters and geometric shape of the aircraft for the flight profile which is given by varying the geometric shape of the aircraft and the associated aerodynamic characteristics of the aircraft; the fourth one is the problem of choosing the parameters of the flight profile. Moreover, the first task is an integral part of the second one, the second one is an integral part of the third, and the third one is an integral part of the fourth. Thus, the composition of these tasks allows solving the complex problem of choosing the parameters of the flight profile, aircraft and its PP.Another disadvantage of the applied methods is the choice of a single solution based on one criterion. In practice, the choice of the solution depends on many factors; therefore, it is advisable to have a number of solutions that slightly differ in the chosen criterion, but have different vectors of flight, aircraft and PP parameters. A method of selecting the composition and parameters of the PP according to the one criterion, which ensures the receipt of a number of vectors of the PP parameters with the aim of the subsequent selection of the parameter vector that satisfies a number of criteria is proposed in the article. In addition, the use of a complete mathematical model which is used the differential equations of aircraft motion in the optimization task requires large computing resources. A more rational method is a rough search for a solution using a simplified model, followed by a correction of the solution result using a complete model ("predictor-corrector" type methods). The method of choosing parameters using the "predictor - corrector" scheme is proposed in the article. The predictor is a simplified model based on the use of the cruising flight segment for the selection of aircraft and PP parameters. The corrector is the complete model using the differential equations of aircraft motion and fuel consumption, applied to all segments of the aircraft flight profile.The developed method provides obtaining a number of PP parameter vectors that are best according to the given efficiency criterion, which makes it possible to make a subsequent choice of the PP parameters vector taking into account all efficiency criteria.

Improving aerodynamic characteristics for drag reduction of heavy truck

Significant increasing vehicle performance can be achieved by reducing aerodynamic drag because of rising average speeds and reducing fuel consumption. Russian truck manufacturers do not prioritize the truck aerodynamic issues, therefore majority of existed models has a very high value of drag coefficient, and moreover, vehicles older than 10 years predominate in operation. In this regard, against the background of rising prices for liquid fuel, the reduction in aerodynamic drag allows to solve the problems posed. The article presents the results of a study of the aerodynamic drag coefficient for KAMAZ heavy truck when using a set of cab fairings of different shapes. Using the software, the analysis of the influence of the shape of the fairing on the coefficient of air resistance of the car is made. As a result, fuel economy is calculated taking into account the selected optimal cab fairing and cab–side extenders from the aerodynamic drag coefficient

On the way to the optimal design of an inflatable aerodynamic decelerator of space debris removal system for CubeSat nanosatellites

In order to avoid pollution of the near-Earth space out-of-service small spacecrafts could be transferred to the disposal orbits in dense atmosphere with the help of inflatable decelerator. The issues of aerodynamics and heat transfer are of key importance for such systems design. The movement conditions in a low Earth orbit of a spherical inflatable aerodynamic decelerator designed for small spacecrafts removal are considered. The preliminary results of thermal analysis of the decelerator made of polymer film with the surface metallization are presented.

Problems of an Aerodynamic Interference between Helicopter Rotor Slipstream and an Elevated Heliport

Abstract An elevated heliport, as it has been defined by FAA (Federal Aviation Administration), is a heliport located on a rooftop or other elevated structure where the TLOF (touchdown and lift-off area) is at least 30 inches (76 cm) above the surrounding surface [1]. One of greatest advantages of such heliports is that they require less free space, which eases its build nearby existing buildings – especially in densely built-up areas. However, design of such heliports is more complicated, than ground level ones, while one must include an aerodynamic impact of the building below the elevated heliport and surrounding buildings. The aerodynamic interference between the helicopter and the buildings may result with decline of flight safety, due to sudden decrease of thrust (when flying above the edge of building) or because of increased turbulence in windy weather, wake behind surrounding buildings causing sudden gusts etc. Moreover, oscillations of pressure caused by helicopter rotor influence on the building structure also must be taken into account due to increased wear of upper part of the building or devices mounted on its roof (for example, elevator drives). These oscillation may also cause vibrations of building’s structure, which is especially important in case of medical heliports – which are a vast majority of elevated heliports (and heliports in general) – because of strict requirements for acceptable vibration level. The article is aimed on summarize aerodynamic issues, which should be taken into account during design of elevated heliport.

Powered wind tunnel tests setup of the IRON innovative turboprop aircraft

This paper describes the powered wind tunnel tests setup of the innovative configuration of the IRON regional turboprop aircraft. The objective of the tests is the evaluation of propulsive effects on aircraft stability and control characteristics. During the setup process, several aerodynamic issues have been anticipated and here illustrated. A scaled engine deck has been derived from the full-scale data provided by the IRON powerplant consortium partner. From two representative flight conditions, the characteristics of the scaled motor as RPM, torque and power have been calculated, providing a choice for the electric motors to install in the test section. The motors’ operating voltage and current determined the sizing of the power, acquisition and control system. Similarly, the desired propeller coefficients were the target of a propeller design process, which was performed with XROTOR, MATLAB®, XFOIL and validated with RANS analyses. Finally, to directly evaluate the propeller thrust and normal force, motors’ supporting structures with load cells have been conceptually designed.

Conceptual design and CFD analysis of a new prototype of agricultural aircraft

In the agricultural aviation, there are several aerodynamic factors that must be optimized in order to contribute to the successful application of agricultural products, such as the high aerodynamic efficiency (L/D) required at the working phase and the influence of aircraft wingtip phenomena on the spray deposition and movement. For these reasons, in this research is presented the conceptual design of an advanced prototype of agricultural aircraft, whose main characteristic is an adaptive multi-winglet device installed on the wingtips, which optimized the main aerodynamic issues presented in its mission. Traditional aircraft design methods were used to develop and assess the suitability of the aircraft, focusing on its design requirements and tackling studies of weight sizing, pilot ergonomics, aerodynamics, stability, and performance. Subsequently, analytical and computational methods were used to design the adaptive multi-winglet device, which is composed by three winglets with its own geometry fitted on a tip-tank. Six configurations were created by modifying only the cant angle of each winglet in order to determine the arrangement that provides the best aerodynamic characteristics through a study of computational fluid dynamics (CFD), using the Reynolds–Averaged–Navier–Stokes (RANS) equations coupled with the Shear Stress Transport (SST) turbulence model. First, the flow around the wing and the multi-winglet section of the aircraft was investigated exclusively. Afterward, the airflow around the entire aircraft was studied at the product application condition, in order to compare the overall aerodynamic performance of the baseline concept along with the optimal multi-winglet configuration installed on the aircraft. Lift, drag and pitching moment coefficients were assessed, as well as the wingtip vortex structure of the most relevant configurations. Results of this study showed that adaptive multi-winglet devices are a promising alternative to improve the overall performance of an agricultural aircraft, because they provide control over the size and strength of the wake-spray interaction on the sprayed product, reduce the induced drag, reduce the bending moment and improve the aerodynamic efficiency of the aircraft.

The influence of distance between vehicles in platoon on aerodynamic parameters

The paper presents the results of experimental and numerical research focused on the reduction of fuel consumption of vehicles driving one after another in a so-called platoon arrangement. The aerodynamic parameters and safety issues were analyzed in order to determine the optimal distance between the vehicles in traffic conditions. The experimental research delivered the results concerning the drag and was performed for simplified model of two vehicles positioned in wind tunnel equipped with aerodynamic balance. The additional numerical analysis allowed investigating the pressure and velocity fields as well as other aerodynamics parameters of the test case.

Methodology for the Assessment of Distributed Propulsion Configurations with Boundary Layer Ingestion Using the Discretized Miller Approach

The growing global environmental awareness has motivated the search for more fuel-efficient aircraft propulsion systems. In this context, a configuration based on distributed propulsion with Boundary Layer Ingestion (BLI) has been found to present potential performance benefits. The concept has been documented and explored extensively during the last few years and various aerodynamic integration issues, such as: high levels of distortion and low intake pressure recovery; have been identified as factors that may be detrimental in realizing the technology full potential. Parametric and parallel compressor (PC) approaches have been used to assess the effect of these aerodynamic issues on propulsors fan performance. However, in the context of BLI, these tools are unable to assess the effects of combined radial and circumferential distortion that are present. In order to assess the combined distortion patterns and the effects of distortion at component and system levels, this study uses a novel method based on semi-empirical correlations denominated the Discretized Miller (DM) approach. This method was developed for BLI systems previously by the author, and it is now incorporated into the propulsor performance method to assess the effects of the combined radial and circumferential distortion patterns. The performance analysis, undertaken at a component and system level, aims to assess several propulsion architectures, using Thrust Specific Fuel Consumption (TSFC) as figure of merit. To define the suitability of the distributed propulsor array in this study, an airframe layout based on the N3-X aircraft concept and High Temperature Superconducting (HTS) electric motor capabilities were assumed. The key contribution of this study is to enable the introduction of the concept of thrust split between energy source and propulsion system in the system analysis, and thereby, allows the assessment of its effects on different propulsion system layouts, while considering the BLI induced distortion. The results obtained with this alternative performance method showed that BLI reduces the fan efficiency of a conventional fan by approximately 2%, whilst corroborating the TSFC trends observed in previous studies. The study also indicates that when sizing effects of propulsors and core-engines were neglected, a propulsion system configuration with 75% thrust split was found optimum.

Wind induced vibrations of a high tapered obelisk: wind tunnel tests, numerical analysis and design of countermeasures

The structure studied in this paper is a 85 meters high tapered obelisk, made of reinforced concrete for the first 9 meters and of steel welded plates for the upper 76 meters. Its bluff cross section consists of two closely spaced triangular sections that are scaled linearly with the height from ground. Having a complex bluff section and being a light structure, aerodynamic instabilities and vortex induced vibrations were investigated using a mixed experimental-numerical approach, in order to define wind loads for the structural design, and possible interventions aimed at mitigating the dynamic effects due to wind action. Exploiting the regular tapering of the obelisk section, a rigid sectional model with constant section was initially tested in wind tunnel: static aerodynamic coefficients and vortex-induced response as a function of the Scruton number were measured for several angles of attack. The experimental sectional results were successively used to assess numerically the response of the structure considering tapering, the gradient of wind speed, the modal shapes, and the correlation of wind actions. Even though the numerical analysis showed that the tapering drastically reduces aerodynamic issues, the achieved results underlined the pressing need to increase the damping of the structure in order to avoid galloping and vortex induced vibrations for wind speeds within the design range; to this aim tuned mass dampers were designed.

Issues of contemporary wind engineering and aerodynamics of building structures

The paper reviews nowadays problems and issues of wind engineering and aerodynamics of building structures. The article mainly focuses on aerodynamics of building structures, shortly characterizing theoretical bases, which one must take into account when assuming wind loads. The three different approaches of collecting information in the field of wind loads are described: in-situ measurements, wind tunnel tests and numerical simulations. Also, a review of the most important contemporary issues of wind engineering is presented.

Design a mechanism Like flapping hummingbird wings

Hummingbirds have been considered because they have high maneuverability. Making an example of this type of bird needs to observe the kinematic and aerodynamic issues of the bird’s flight. In this article the locus of attack angle and instantaneous elevation is studied to be used for constructing a sample of birds. At first, the charts offered in the article of bird’s flight was digitized and by using MATLAB software was fitted to the shape of a sinusoidal equation to be comparable with designed mechanisms. The designed mechanisms have three variables that by using EES software the motion equation has been approached. Then by the Lagrange Interpolation the effect of each variable in the equation of motion mechanism obtained. Finally by using EES software these equation is solved and the amount of the variables was calculated.

Design point analysis of the turbofan-driven turboelectric distributed propulsion system with boundary layer ingestion

The performance benefits of boundary layer ingestion in the case of air vehicles powered by distributed propulsors have been documented and explored extensively by previous study. However, the increased inlet flow distortion and the system total weight would dramatically reduce the expected benefits. In this paper, a novel turboelectric distributed propulsion module on the N3-X airframe has been developed. It includes two direct-shaft-driven turbofans (each drives a free power turbine) and a propulsors array, and therefore both the direct-shaft-driven turbofan and the propulsors unit produce thrust. Secondly, a parametric and quasi two-dimensional study at component and at system level is carried out so that the effects of these two aerodynamic issues over the system performance can be assessed. The figure of merit in this study is the thrust-specific fuel consumption and the system parameters examined are: the thrust split between propulsors and engines, the capture height and the direct-shaft-driven turbofan parameters. Preliminary results found optimum configurations at around 60–90% thrust split ratio, when installation effects were neglected. The final value depends on the propulsor intake pressure loss and the bypass ratio of the propulsion system.