Search results

Rainfall is one of the main atmospheric conditions that significantly affect the aerodynamic performance of the low Reynolds number flights. In this paper, the adverse effects of rain on the aerodynamic performance of a two-dimensional (2D) airfoil with a chord-based low Reynolds number of 2 × 10⁵ and the mini-unmanned aerial vehicle (UAV) for various flight conditions, i.e. 0°–40° at Mach number 0.04 were studied numerically. The purpose of this study is to explore the aerodynamic penalties that affect the liquid water content (LWC = 5.33) of the airfoil and UAV performance in rain under different flying conditions.

The Eulerian–Lagrangian two-phase flow method is adopted to simulate the rain environment over an airfoil and mini-UAV aerodynamic performances. The Reynolds Averaged Navier–Stokes equations are considered to solve the time-averaged equations of motion for fluid flow.

The effect of rainfall on the airfoil and mini-UAV is studied numerically and validated experimentally. For 2D airfoil, the lift and drag coefficients for both numerical and experimental results show a very good correlation at Reynolds number 2 × 10⁵. For three-dimensional (3D) mini-UAV, the lift and drag coefficients for both numerical and experimental results show a very good correlation at Mach number 0.04. The raindrops distribution around the airfoil, premature trailing edge separation, boundary-layer velocity profiles at five different chord positions (i.e. LE, 0.25c, 0.5c, 0.75c and 0.98c) on the upper surface of the airfoil, water film height and the location of rivulet formation on the upper surface of the airfoil are also presented.

For 2D airfoil, the recorded maximum variation of the coefficient of lift and lift-to-drag (L/D) ratio is observed to be 5.33% at an 8° and 10.53% at a 4° angle of attack (AOA) between numerical and experimental results under the influence of rainfall effect for LWC = 5.33. The L/D ratio percentage degradation is seen to be 61.9% at an AOA of 0°–2° for the rain environment. For 3D mini-UAV, the recorded maximum variation of the coefficient of lift and L/D ratio are observed to be 2.84% and 4.60% at a 30° stall AOA under the influence of rainfall effect for LWC = 5.33. The numerical results are impressively in agreement with the experimental results. UAV designers will benefit from the findings presented in this paper. This will be also helpful for training the pilots to control the airplanes in a rain environment.

This paper aims to deal with the numerical investigation of laminar separation bubble (LSB) characteristics (length and height of the bubble) of SS007 airfoil at the chord Reynolds number of Re_c = 0.68 × 10⁵ to 10.28 × 10⁵.

The numerical simulations of the flow around SS007 airfoil were carried out by using the commercial fluid dynamics (CFD) software, ANalysis system (ANSYS) 15. To solve the governing equations of the flow, a cell-centred control volume space discretisation approach is used. Wind tunnel experiments were conducted at the chord-based Reynolds number of Re_c = 1.6 × 10⁵ to validate the aerodynamic characteristics over SS007 airfoil.

The numerical results revealed that the LSB characteristics of a SS007 airfoil, and the aerodynamic performances are validated with experimental results. The lift and drag coefficients for both numerical and experimental results show very good correlation at Reynolds number 1.6 × 10⁵. The lift coefficient linearly increases with the increasing angle of attack (AOA) is relatively small. The corresponding drag coefficient was found to be very small. After the formation of LSB which leads to burst to cause airfoil stall, the lift coefficient decreases and increases the drag coefficient.

Low Reynolds number and LSB characteristics concept in aerodynamics is predominant for both civilian and military applications. These include high altitude devices, wind turbines, human powered vehicles, remotely piloted vehicles, sailplanes, unmanned aerial vehicle and micro aerial vehicle. In this paper, the micro aerial vehicle flight conditions considered and investigated the LSB characteristics for different Reynolds number. To have better aerodynamic performances, it is strongly recommended to micro aerial vehicle (MAV) design engineers that the MAV is to fly at 12 m/s (cruise speed).

MAVs and unmanned aerial vehicles seem to give some of the technical challenges of nature conservation monitoring and law enforcement a versatile, reliable and inexpensive solution.

The SS007 airfoil delays the flow separation and improves the aerodynamic efficiency by increasing the lift and decreasing the drag. The maximum increase in aerodynamic efficiency is 12.5% at stall angle of attack compared to the reference airfoil at Re = 2 × 10⁵. The results are encouraging and this airfoil could have better aerodynamic performance for the development of MAV.

In a microburst wind, the profiles and characteristics are significantly different from those of normal boundary layer winds. The objective of this work is to study the microburst effect on the performance of aircraft for providing guidelines to frame escape strategies.

Large eddy simulation model is used to study the effect of microburst by simulating the actual physical process of microburst-generated downdraft environment over the unmanned aerial vehicle. In this work, an attempt has been made to simulate the dry microburst (microburst not accompanied by rain) numerically using the impinging jet model to explore the effect of microburst at 12° angle of attack for flight take-off condition with a Mach number 0.04.

The numerical results revealed the aerodynamic performance loss of an aircraft in the microburst-generated downdraft during take-off condition quantitatively. This could be a more valuable information to the aviation industry. The authors believe that the results shown in this paper will be useful for the designers of aircraft. This will also help train the pilots to control the airplanes in a microburst environment.

Severe thunderstorms are significant weather phenomena that have a significant impact on various facets of national activity, including civil and defence operations, specifically aviation, space vehicle launch and agriculture, in addition to their potential to cause damage to life and property.

The maximum percentage of pressure increases on the upper surface of the aircraft between 2 and 7 s is 99.86% under the microburst-generated downdraft condition. The flight escape maneuver could be initiated, before increasing the pressure on the upper surface of the aircraft. The aircraft flies with high airspeed through the microburst environment, where the microburst-generated downdraft is most severe.

The heatwave effects over an airfoil have a greater influence in the aerodynamic efficiency. The purpose of this study is to investigate the effects of heatwave upon the low Reynolds number airfoil aerodynamic performance.

In this research, the heatwave effects on micro-aerial vehicles’ wing operation are also demonstrated both numerically and experimentally, at the Chord-based Reynolds number Re_c = 2 × 10⁵, and under the influence of various environmental temperatures, i.e. 27ºC (room temperature), 40ºC and 50ºC for various flying conditions. A numerical investigation of the low Reynolds number flows with the thermal effect around the unmanned aerial vehicle is presented using the k–ɛ turbulent model. Besides that, the low Reynolds number-based wind tunnel experimental setup is developed to determine the effects of a heatwave over an airfoil. Then, the numerical simulations and wind tunnel experiments are conducted.

The numerical and wind tunnel’s experimental investigations have been performed on a 2D airfoil under a heatwave environment, i.e. 27ºC, 40ºC and 50ºC for different flight conditions. The numerical and experimental results revealed that the heatwave effect and aerodynamic performance are validated with experimental results. The lift and drag coefficients for both numerical and experimental results show very good correlation at Reynolds number 2 × 10⁵.

The consequences of the increasing temperatures to varying degrees will also be experienced by all commercial aircraft. That is why some great findings are presented here, which are highly relevant for the current and future airline operations. However, sooner than later, the aviation industry should also begin to consider the rising effects of temperature on aircraft operations to develop the loss-reducing adaptable plans.

From the numerical and wind tunnel experimental results, the recorded maximum lift coefficients are observed to be 2.42, 2.39 and 2.36 for 27ºC (room temperature), 40ºC and 50ºC, respectively, at 16° angle of attack, numerically. Similarly, the recorded maximum lift coefficients are observed to be 2.410, 2.382 and 2.354 for 27ºC (room temperature), 40ºC and 50ºC, respectively, at 16° angle of attack, experimentally. The heatwave effects over an airfoil have a greater influence in the aerodynamic efficiency.

In today’s highly competitive global business environment, there is a growing demand for professionals who possess well-developed soft skills. Such abilities include flexibility, effective communication and other skills. Soft skills are personal attributes and qualities that are more closely related to the emotional side of human beings. Individuals must cultivate and hone soft skills during their undergraduate studies. These skills, also known as interpersonal or non-technical skills, are essential to complement hard skills and pave the way for a thriving career trajectory. Soft skills are developed over the course of one’s career and are indispensable in establishing a strong, professional presence in the corporate or academic realm. The field of engineering is no exception in this regard, and the business approach during the engineering course is of significant relevance. By acquiring soft skills, engineering graduates will become competitive and adaptable professionals capable of handling the current and future challenges of the job market. The purpose of this study is to investigate the soft skills that students perceive as being better developed during their business classrooms in the engineering course and identify areas for improvement in the business education process.

The research method consisted in four different phases from variables identification to statistical analyses. Then, as part of this approach a structured questionnaire was administered at the end of the engineering course, where students rated their perception of the degree of development of each of the soft skills covered in the course on a scale of zero to ten. The collected data were analysed using multivariate analysis techniques, including factorial analysis.

The results of the study demonstrate that the set of skills acquired by individuals in business classrooms pursuing a degree in industrial engineering is in high demand by potential employers. Such skills are deemed essential for the successful operation of businesses in modern-day industries. The findings of this research validate the significant role that industrial engineering students play in fulfilling the requirements of the job market and pave the way to meaningful insights on how to approach this topic during the business education process in engineering courses.

The findings bring about significant insights for national educational councils and ministries, universities and educational stakeholders in the process of updating, rethinking and implementing new curricula criteria in higher education, particularly in the Latin American context.

This paper enriches the literature by assessing the development of soft skills of engineering students in the Latin American context. The research reinforces the importance of developing soft skills aligned with those required for the context of current and future labour markets.

Nowadays flaps and winglets are one of the main mechanisms to increase airfoil efficiency. This study aims to investigate the power performance of vertical axis wind turbines (VAWT) that are equipped with diverse gurney flaps. This study could play a crucial role in the design of the VAWT in the future.

In this paper, the two-dimensional computational fluid dynamics simulation is used. The second-order finite volume method is used for the discretization of the governing equations.

The results show that the gurney flap enhances the power coefficient at the low range of tip speed ratio (TSR). When an angled and standard gurney flap case has the same aerodynamic performance, an angled gurney flap case has a lower hinge moment on the junction of airfoil and gurney flap which shows the structural excellence of this case. In all gurney flap cases, the power coefficient increases by an average of 20% at the TSR range of 0.6 to 1.8. The gurney flap cases do not perform well at the high TSR range and the results show a lower amount of power coefficient compare to the clean airfoil.

The angled gurney flap which has the structural advantage and is deployed to the pressure side of the airfoil improves the efficiency of VAWT at the low and medium range of TSR. This study recommends using a controllable gurney flap which could be deployed at a certain amount of TSR.

Modern unmanned air vehicles (UAVs) are usually equipped with rotors connected to electric motors that enable them to hover and fly in all directions. The purpose of the paper is to design optimal composite rotor blades for such small UAVs and investigate their aerodynamic performances both computationally and experimentally.

Artificial intelligence method (genetic algorithm) is used to optimize the blade airfoil described by six input parameters. Furthermore, different computational methods, e.g. vortex methods and computational fluid dynamics, blade element momentum theory and finite element method, are used to predict the aerodynamic performances of the optimized airfoil and complete rotor as well the structural behaviour of the blade, respectively. Finally, composite blade is manufactured and the rotor performance is also determined experimentally by thrust and torque measurements.

Complete process of blade design (including geometry definition and optimization, estimation of aerodynamic performances, structural analysis and blade manufacturing) is conducted and explained in detail. The correspondence between computed and measured thrust and torque curves of the optimal rotor is satisfactory (differences mostly remain below 15%), which validates and justifies the used design approach formulated specifically for low-cost, small-scale propeller blades. Furthermore, the proposed techniques can easily be applied to any kind of rotating lifting surfaces including helicopter or wind turbine blades.

Blade design methodology is simplified, shortened and made more flexible thus enabling the fast and economic production of propeller blades optimized for specific working conditions.

The purpose of this study is to identify the possible relation between the vibration and the stall by using the vibration response of the airfoil. For this purpose, the root mean square values of the acceleration signals are evaluated to demonstrate the compatibility between the stall angles and the vibration levels.

An experimental study is conducted on NACA 4415 airfoil at Reynolds numbers 69e3, 77e3 and 85e3. Experiments are performed from 0° to 25° of the angles of attack (AoA) for each Reynolds number condition. To observe the change of the vibration values at the stall region clearly, experiments are performed with the AoA ranging from 10° to 25° in 1° increments. Three acceleration sensors are used to obtain the vibration data.

The results show that the increase in the amplitude of the vibration is directly related to the decrease in lift. These findings indicate that this approach could be beneficial in detecting stall on airfoil-type structures.

This study proposes a new approach for detecting stall over the airfoil using the vibration data.

The purpose of this paper is to examine whether satisfaction of employers with skill competencies of fresh engineering graduates (EGs) in India is impacted by their expectations and perceptions. Applying Expectation Confirmation Theory (ECT), the authors have also proposed and tested whether such effects on employers’ satisfaction are mediated by (dis)confirmation.

Data were collected through a survey of employers’ representatives using a structured questionnaire. The proposed mediation model has been tested on a sample of 284 with Confirmatory Factor Analysis by applying structural equation modelling in AMOS.

The structural model has been constructed with six latent constructs in accordance with extant literature. Excluding some observed variables, the structural model was found to have a good model fit. The measurement model is in accordance with ECT. Three of the four independent variables (two related to employers’ expectations and one to employers’ perception) exert significant influence on employers’ satisfaction, with (dis)confirmation as a mediator.

Industry–academia partnerships need to be an integral feature of any curriculum to bridge the gap between course curricula on one hand and employers’ expectations and perceptions on the other.

Past research on employability of EGs has mostly explored a direct association between employers’ perception and satisfaction. The authors study contributes to literature by examining the role of employers’ expectations in addition to their perception as precursors of their satisfaction, using the framework of ECT. Outcomes reported are of relevance to multiple stakeholders in technical education.

This study aims to obtain the lowest surface roughness (Ra) and drill bit adhesion values (AV) depending on the change in control factors (cutting speed-Vc, feed rate-f and drill bit-D) during drilling of the Al 5083 H116 alloy. Low roughness values increase the fatigue strength of the final part and affect tribological properties such as lubrication and friction. In the machining of ductile materials, the AV increases the Ra value and negatively affects the tool life.

Drilling tests were conducted using Taguchi L16 orthogonal array. The experimental measurement findings for Ra and AV were adjusted utilizing the Grey Relational Analysis (GRA), the Response Surface Method (RSM) and Artificial Neural Networks (ANN) to generate prediction values. SEM detected drill-tip adhesions and chip morphology and they were analyzed by EDX.

Ra and AV increased as the f increased. Vc affects AV; 86.04% f on Ra and 54.71% Vc on AV were the most effective control parameters. After optimizing Ra and AV using GRA, the f is the most effective control factor. Vc: 120 m/min, f: 0.025 mm/rev and D2 were optimal. ANN predicted with Ra 99.6% and AV 99.8% accurately. Mathematical models are obtained with RSM. The increase in f increased AV, which had a negative effect on Ra, whereas the increase in Vc decreased the adhesion tendency. With the D1 drill bit with the highest flute length, a relatively lower Ra was measured, as it facilitates chip evacuation. In addition, the high correlations of the mathematical models obtained indicate that the models can be used safely.

The novelty of this study is to determine the optimum drilling parameters with GRA and ANN for drilling the necessary holes for the assembly of ammunition wing propulsion systems, especially those produced with Al 5083 H116 alloy, with rivets and bolts.