Search results

In recent years, in parallel with the increasing air traffic and the number of passengers in air transport, the number of people exposed to aircraft-induced noise has increased significantly. Especially people living in the areas close to the airports are affected by noise emission during the landing, take-off, taxi and ground operations. Negative effects of noise such as sleep disturbance, lack of concentration, anxiety and high blood pressure cardiac diseases were determined directly or indirectly for human health. For this reason, examining the noise effect caused by aircraft and determining the necessary measures to be taken is very important for the sustainable development of aviation. In the International Eskisehir Hasan Polatkan Airport (LTBY), this paper aims to calculate a noise mapping following international standards in line with the directives of the International Civil Aviation Organization (ICAO). Also, Annex 8, “Airworthiness of Aircrafts” and Annex 16, “Environmental Protection Volume 1 Aircraft Noise”, which were taken at the International Civil Aviation Convention, were proposed to determine the exposure caused by aircraft noise.

In this paper, noise levels for the day (07.00–19.00), evening (19.00–23.00) and night (23.00–07.00) period around LTBY were predicted and calculated by the use of the IMMI software according to the “ECAC Doc. 29-Interim” method for the prediction and computation of the aircraft noise.

According to the calculated/mapped values, in the 24 hours (Lden), the noise level is 65 dB (A) and above. In the day time zone, the noise level is 63 dB (A) and above. When the calculations for the evening time zone are examined, the noise level is above 58 dB (A). When the calculations for the night time frame are examined, it is calculated that there is no dwelling that is affected by the noise level above 53 dB (A).

Along with future improvements, it is recommended to be applied to other civil airports.

To the best of the authors’ knowledge, there is no previous research in the literature on aircraft noise mapping of LTBY. Also, unlike the software commonly used in other works in the literature, IMMI software was used in this study. Such investigations should be carried out in other civil airports in the coming years to struggle with noise emissions and noise control. If noise boundary values are exceeded, action plans should be developed for a sustainable aviation concept. Along with future improvements, it is recommended to be applied to other civil airports.

The purpose of this study is to perform an exergy analysis of a turbojet engine combustor at different cycle parameters.

Base cycle parameters have been defined for the engine, and then differentiation of the combustor exergy efficiencies and destruction rates have been evaluated by changing overall pressure ratio, combustor exit temperature and combustor pressure ratio.

For the basic engine cycle, combustor unit is found to have lowest exergy efficiency as 62.3 for the sea level static condition. Compressor turbine exhaust and whole engine exergy efficiencies have been calculated as 88.7, 96.5, 68.2 and 69.4, respectively.

Because of the biggest exergy, destruction is seen mainly in combustion system; effect of the combustor inlet pressure (related to the compressor design technology), pressure drop and exit temperature on the exergy efficiencies have been analyzed and combustor second law efficiency have been evaluated.

The investigation’s purposes are highly connected with social wellness and targeted at sustainable development of the society. Practical implementation of the obtained scientific results is directed on the improving of combustor for a turbojet engines and decreasing negative influence on the environment.

As a result of this paper, the following are the contribution of this paper in the field of gas turbine exergy subjects: Combustor has been found as the most critical component in respect of the exergy efficiency. Therefore, the effect of the combustor main cycle parameters such as inlet pressure, combustor pressure ratio and exit temperature have been analyzed.

The purpose of this study is to perform an off-design analysis of the inverted Brayton cycle engine.

The off-design analysis equations of the inverted Brayton cycle engine were first derived in this study and the control parameters of the inverted Brayton cycle engine were first determined and investigated.

It is observed that by controlling the total temperature decrease in cooling section, it is possible to adapt the engine for low specific fuel consumption working conditions or high thrust working conditions. Specific fuel consumption is reduced by 27.1 % by stopping cooling in the cooling section and thrust is increased by 27.6 % by working with full load of the cooling section (500 K temperature decrease in cooling section). It is observed that thrust depending on the flight Mach number increases with an increase in flight Mach number and reaches a peak value at 5.21 flight Mach number and reduces by 80.8 % at 6 flight Mach number relative to the peak value. The specific fuel consumption increases rapidly as the Mach number increases, and the specific fuel consumption is 49.0 g/[kN.s] at Mach 1, reaches 70.4 g/[kN.s] at Mach 5 and increases to 412 g/[kN.s] at Mach 6. The specific fuel consumption increases from 68.1 to 73.0 g/(kN.s) and the thrust decreases from 16.5 to 13.3 kN as the total preburner exit temperature increases from 1,500 to 2,000 K. Specific fuel consumption decreases from 83.1 to 64.8 g/(kN.s) and thrust increases from 4.60 to 11.08 kN depending on afterburner exit total temperature increase from 1,800 to 2,500 K.

The cooling section reduces total temperature of the gas flow to lower values to increase the compressor total pressure ratio. The compressor increases the total pressure of the gas flow to the optimum total pressure ratios to increase the nozzle exit Mach number and gain more thrust. The afterburner increases the total temperature of the gas flow to increase the sound speed in the nozzle exit to increase thrust. The nozzle expands the gas flow to reduce the static pressure of the gas flow to near the optimum value, atmosphere pressure, to increase thrust and reduce specific fuel consumption.

Hypersonic and supersonic air vehicles can use the current engine model for the its own propulsion systems.

After first heavier than air flight, aero engines was designed for only used for aero vehicle. Internal combustion engines were used for propelled propeller aircraft at the first term of aircraft. However, propeller-propelled aircrafts are not sufficient to increase aircraft velocity to supersonic Mach numbers due to the shock losses of propeller, so the supersonic era was only introduced by revolution in propulsion systems with new concept. A jet engine was developed to be candidate for supersonic flight.

Off-design analysis equations of an inverted Brayton cycle engine were first derived in this study. Furthermore, the control parameters of the inverted Brayton cycle engine were first determined and investigated in this paper.

The purpose of this study is to build a high accuracy thrust model under various small turbojet engine shaft speeds by using robust, ordinary, linear and nonlinear least squares estimation methods for target drone applications.

The dynamic shaft speeds from the test experiment of a target drone engine is conducted. Then, thrust values are calculated. Based on these, the engine thrust is modeled by robust linear and nonlinear equations. The models are benefited from quadratic, power and various series expansion functions with several coefficients to optimize the model parameters.

The error terms and accuracy of the model are given using sum of squared errors, root mean square error (RMSE) and R-squared (R²) error definitions. Based on the multiple analyses, it is seen that the RMSE values are no more than 17.7539 and the best obtained result for robust least squares estimation is 15.0086 for linear at all cases. Furthermore, the R² value is found to be 0.9996 as the highest with the nonlinear Fourier series expansion model.

The motivation behind this paper is to propose robust nonlinear thrust models based on power, Fourier and various series expansion functions for dynamic shaft speeds from the test experiments.

The purpose of this paper is to introduce a hybrid, metaheuristic, multimodal and multi-objective optimization tool that is needed for aerospace propulsion engineering problems.

Multi-objective hybrid optimization code is integrated with various benchmark and test functions that are selected suitable to the difficulty level of the aero propulsion performance problems.

Ant colony and particle swarm optimization (ACOPSO) has performed satisfactorily with benchmark problems.

ACOPSO is able to solve multi-objective and multimodal problems. Because every optimization problem has specific features, it is necessary to search their general behavior using other algorithms.

In addition to the optimization solving, ACOPSO enables an alternative methodology for turbine engine performance calculations by using generic components maps. The user is flexible for searching various effects of component designs along with the compressor and turbine maps.

A hybrid optimization code that has not been used before is introduced. It is targeted use is propulsion systems optimization and design such as Turboshaft or turbofan by preparing the necessary engine functions. A number of input parameters and objective functions can be modified accordingly.

The purpose of this paper is to create models that predict exergetic sustainability index (ESI) and environmental effect factor (EEF) values with high accuracy according to various engine parameters.

In this study, models were created to estimate ESI and EEF sustainability parameters in various flight phases for a business jet with a turboprop engine using the cuckoo search algorithm (CSA) method. The database used for modeling includes the various engine parameters (torque, engine airflow, gas generator speed, fuel mass flow, power and air-fuel ratio) obtained by running a business aircraft engine more than once at different settings and the actual ESI and EEF values obtained depending on these parameters. In addition, sensitivity analysis was performed to measure the effect of engine parameters on the models. Finally, the effect of the CSA number of nest (n) parameter on the model accuracy was investigated.

It has been observed that the models predict ESI and EEF values with high accuracy. As a result of the sensitivity analysis, it was seen that the air-fuel ratio had a greater effect on the output parameters.

These models are thought to assist in the exergetic environment analysis used to find the greatest losses for turboprop business jets and identify their causes and further improve system performance. Thus, they will be a useful tool to minimize the negative impact of business jet on environmental sustainability.

To the best of the authors’ knowledge, this study stands out in the literature because it is the first exergo-metaheuristic approach developed with CSA for business aircraft engine; moreover, the data set used consists of real values.

The purpose of this study is to have semiempirical correlations for carbon monoxide (CO), unburned hydrocarbon (UHC) and nitrogen oxide (NO_x) emissions that are collected and calibrated by using experimental data of a tubular-type combustor.

Combustor uses a coflow radial-type air-blast atomizer and is especially designed for the empirical correlation issues. Air mass flow rate, air inlet temperature and air-to-fuel ratio parameters have been changed and different inlet conditions have been created for combustor tests. Six different inlet temperatures from 475 to 350 K have been set for each air mass flow rate. Air mass flow rate values from 0.035 to 0.050 kg/s have been used to create varied combustor aerodynamic loadings.

Increasing combustor inlet temperature decreases the CO and UHC emissions. However, it has an adverse effect in NO_x emissions. Moreover, CO and UHC emissions have an increasing trend by the mass flow rate rise that results an extra aerodynamic loading.

It is difficult to obtain real operating parameters for the combustor. Therefore, as a different approach in respect of the literature, rig test parameters have been used for thermodynamic calculations. Additionally, emission calculations of the combustor design point have been performed based on a conditioned test environment. Moreover, combustor outlet temperature and emission values have been scanned and mean values used for the analysis.

To perform preliminary calculations for these pollutants, designers need experimentally calibrated correlations for the similar combustors.

If the application area of the designed engine is a civil aircraft, emissions are one of the most important issues because of the strict regulations of International Civil Aviation Organization. Therefore, aviation companies are continuously working on reducing of emissions.

A comprehensive study for the preliminary emission calculation of newly designed gas turbine combustors was performed to investigate semiempirical correlations in the atmospheric test rig.

The purpose of the paper is to present component matching and off-design calculations using generic components maps.

Multi objective hybrid optimization code is integrated with turbojet function code. Both codes are developed for the research study. Initially, methodology is applied on a numerical propulsion system simulation (NPSS) example engine cycle calculations. Effect of matching constants are shown. Later, component matching and application is done on JetCat engine. Calculations are compared with measured test data. And additional operating conditions are calculated using the matched component constants.

Obtained matching constants provided very good results with NPSS example and also JetCat test measurements. Optimization algorithm is practical for turbojet engine component matching and off-design calculations. Off-design matching provides information about the turbine and exhaust areas of an unknown turbine engine. Thus it is possible to perform off design calculations at various operating conditions. Finding detailed turbine maps is difficult than finding compressor maps. In that case characteristic turbine curve may be a good alternative.

Selected component maps and the target engine components should be similar characteristics. For a one/two stage turbine, characteristic curves can be applied. Validation should be extended on different type of compressor and turbines.

Operators and researchers usually need more information about the available turbojet engines for increasing the effective usage. Generally, manufacturers do not provide such detailed information to public. This study introduces an alternative methodology for engine modeling by using generic component maps and thus obtaining information for off-design calculations. User is flexible for selecting/scaling the compressor and turbine maps.

A hybrid optimization code is used as a new approach. It can be used with other engine functions; for instance functions corresponding to turboshaft or turbofan engines, by modifying the engine function. Number of input parameters and objective functions can be modified accordingly.

The purpose of this paper is to explain the extent and content of the sustainability disclosure of public and foundation (private but not-for-profit) universities in Turkey.

Subsequent to a systematic literature review of six academic databases and the National Thesis Center, a content analysis using a combination of Global Reporting Initiative and campus assessment tools from previous studies is conducted on stand-alone sustainability reports and websites of a purposive sample of eight universities in Turkey.

Infrequent and unsystematic sustainability practice done through websites seems to be more prevalent than formal reporting through international initiatives. Research and practice diverge by focusing on different sustainability indicators. Sustainability needs to be integrated into teaching and curriculum through university policies and regulations. Foundation universities show greater effort in sustainability reporting than public universities.

The research is limited by the availability of mostly self-reported, dispersed and unaudited data by foundation universities in addition to framework-imposed specificities. Furthermore, there is only one public university with a formal sustainability report in the sample.

The findings offer suggestions for developing extra sustainability indicators and may assist local policy-makers and researchers in their efforts to improve sustainability reporting by local universities.

This comprehensive research effort is one of the few studies from a non-Western country perspective and the only study on Turkey in relation to universities and sustainability reporting.

The aim of this qualitative study was to determine what makes school principals successful. The study obtained data through interviews, both face-to-face and via e-mail correspondence. Content analysis provides the framework for analyzing the data. The data revealed that successful school principals have three different, but interrelated competencies, which are personal, administrative, and leadership competencies. The study also indicates that those successful principals gave priority to human relations, they see the school as their home where principals created a warm atmosphere, communicated effectively with all stakeholders, committed themselves to their schools, managed schools in a democratic way, solved problems on time and effectively.