Aircraft Engineering and Aerospace Technology最新文献

Purpose

One of the sectors most affected by the variable weather events caused by climate change and global warming is the aviation sector. Especially in aircraft accidents, weather events increasing with climate change and global warming are effective. The purpose of this study is to determine how much the change in weather conditions caused by global warming and climate changes affect the aircraft in the world between the years 2010 and 2022.

Design/methodology/approach

In this study, it was investigated which weather events were more effective in aircraft crashes by determining the rates of air events and aircraft crashes in aircraft crashes with a passenger capacity of 12 or more that occurred between 2010 and 2022.

Findings

It is clearly seen that increasing weather conditions with global warming and climate change increase the effect of weather conditions in aircraft crashes.

Originality/value

The difference of this study from other studies is the evaluation of the data of the past 12 years, in which the increasing consequences of global warming and climate change have been felt more. It also reveals the necessity of further research on the effects of weather conditions on aircraft.

Purpose

The purpose of this study reports the effects of aspect ratio (AR) on mean flow characteristics of the cruciform orifice jet.

Design/methodology/approach

The aspect ratio is the height-to-width ratio of the lobe of the cruciform shape. The aspect ratios considered are 0.25, 0.5, 0.75, 1, 2, 3 and 4. The turbulent jet flow is issued through an orifice being fitted to the jet tunnel facility. The velocity measurements are recorded with the help of pitot-static tube connected to a digital manometer setup. The Reynolds number calculated using the equivalent diameter 50.46 × 10^–3 m and exit velocity 51.23 m/s was 1.75 × 10⁵. Based on the experimental data, the streamline velocity decay plots, the potential core length (PCL), mean velocity profiles and velocity half widths were plotted, and discussions were made based on the measured data. A smoke-based flow visualization was carried out at moderate Reynolds number 5396.

Findings

The PCL remains almost constant for the aspect ratio 0.25:1 and then starts decreasing for the aspect ratio 1:4. The decrease in PCL indicates improved mixing. The off-center peaks are found along the major axis in mean velocity profiles for almost all cruciform jets. More than one axis switching occurs and can be identified by the crossover points. The location of the first crossover point shifts forward, and the second crossover point shows an oscillating trend. The flow visualization exhibits the jet evolution, and the distance up to which the jet maintains the cruciform shape is increased with the aspect ratio.

Research limitations/implications

The experiments are limited to air in air jet under isothermal conditions.

Social implications

The cruciform orifices can be used as fuel injectors and in air-conditioning systems, thereby improving efficiency and energy usage.

Originality/value

The aspect ratio effects on PCL and axis switching are used to explain the mixing characteristics. Flow visualization was also used to support the discussion.

Purpose

This study aims to achieve optimum flow separation control for a road vehicle using a reverse flow fan on rear side.

Design/methodology/approach

A full-length reverse flow fan array (fan’s air speed is 50% of the car’s speed) is attached throughout the width of the vehicle at rear edge corner.

Findings

The reverse flow fan array positioned at rear edge of car pushes the airflow against the car’s rear window. It creates the recirculation region and alters the pressure distribution. This reduces the lift coefficient by 150%, which becomes the downforce and reduces the drag coefficient by 22%. As the car speed increases, fan speed should also be increased for effective flow control.

Research limitations/implications

This active flow control method for 3D Ahmed car body has been studied computationally at low speed (40 m/s).

Practical implications

This design increases the downforce, thus gives better cornering speed and stability, and decreases the drag which improves fuel efficiency. It can be used for effective flow control of cars (hatchback/sedan). The findings can be applied to the bluff bodies, road vehicles, UAV and helicopter fuselage for flow separation control.

Originality/value

The fan array is attached on car’s rear side, which blows air against the car’s rear window. It alters the pressure distribution and aerodynamics forces favorably. But the existing high-speed fan used in a sports cars sucks the air from bottom and pushes it rearward, which increases both the traction force and drag.

Purpose

The purpose of this study is to design a radio altimeter antenna whose production process is facilitated and can work with multiple-input multiple-output (MIMO) properties to provide space gain on the aircraft.

Design/methodology/approach

To create an easy-to-produce MIMO, a two-storied structure consisting of a reflector and a top antenna was designed. The dimensions of the reflector were prevented to get smaller to supply easy production. The unit cell nearly with the same dimensions of a lower frequency was protected through the original cell design. The co-planar structure with the use of a via connection was modified and a structure was achieved with no need to via for easy production, too. Finally, the antennas were placed side by side and the distance between them was optimized to achieve a MIMO operation.

Findings

As a result, an easy-to-produce, compact and successful radio altimeter antenna was obtained with high antenna parameters such as 10.14 dBi gain and 10.55 dBi directivity, and the conical pattern along with proper MIMO features, through original reflector surface and top antenna system.

Originality/value

Since radio altimeter antennas require high radiation properties, the microstrip antenna structure is generally used in literature. This paper contributes by presenting the radio altimeter application with antenna-reflective structure participation. The technical solutions were developed during the design, focusing on an easy manufacturing process for both the reflective surface and the upper antenna. Also, the combination of International Telecommunication Union’s recommended features that require high antenna properties was achieved, which is challenging to reach. In addition, by operating the antenna as a successful MIMO, two goals of easy production and space gain on aircraft have been attained at the same time.

Purpose

The purpose of this research paper is to recover the autonomous flight performance of a mini unmanned aerial vehicle (UAV) via stochastically optimizing the wing over certain parameters (i.e. wing taper ratio and wing aspect ratio) while there are lower and upper constraints on these redesign parameters.

Design/methodology/approach

A mini UAV is produced in the Iskenderun Technical University (ISTE) Unmanned Aerial Vehicle Laboratory. Its complete wing can vary passively before the flight with respect to the result of the stochastic redesign of the wing while maximizing autonomous flight performance. Flight control system (FCS) parameters (i.e. gains of longitudinal and lateral proportional-integral-derivative controllers) and wing redesign parameters mentioned before are simultaneously designed to maximize autonomous flight performance index using a certain stochastic optimization strategy named as simultaneous perturbation stochastic approximation (SPSA). Found results are used while composing UAV flight simulations.

Findings

Using stochastic redesign of mini UAV and simultaneously designing mini ISTE UAV over previously mentioned wing parameters and FCS, it obtained a maximum UAV autonomous flight performance.

Research limitations/implications

Permission of the directorate general of civil aviation in the Republic of Türkiye is essential for real-time UAV autonomous flights.

Practical implications

Stochastic redesign of mini UAV and simultaneously designing mini ISTE UAV wing parameters and FCS approach is very useful for improving any mini UAV autonomous flight performance cost index.

Social implications

Stochastic redesign of mini UAV and simultaneously designing mini ISTE UAV wing parameters and FCS approach succeeds confidence, highly improved autonomous flight performance cost index and easy service demands of mini UAV operators.

Originality/value

Creating a new approach to recover autonomous flight performance cost index (e.g. satisfying less settling time and less rise time, less overshoot during flight trajectory tracking) of a mini UAV and composing a novel procedure performing simultaneous mini UAV having passively morphing wing over certain parameters while there are upper and lower constraints and FCS design idea.