The purpose of this study is to have semiempirical correlations for carbon monoxide (CO), unburned hydrocarbon (UHC) and nitrogen oxide (NOx) emissions that are collected and…
Abstract
Purpose
The purpose of this study is to have semiempirical correlations for carbon monoxide (CO), unburned hydrocarbon (UHC) and nitrogen oxide (NOx) emissions that are collected and calibrated by using experimental data of a tubular-type combustor.
Design/methodology/approach
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.
Findings
Increasing combustor inlet temperature decreases the CO and UHC emissions. However, it has an adverse effect in NOx emissions. Moreover, CO and UHC emissions have an increasing trend by the mass flow rate rise that results an extra aerodynamic loading.
Research limitations/implications
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.
Practical implications
To perform preliminary calculations for these pollutants, designers need experimentally calibrated correlations for the similar combustors.
Social implications
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.
Originality/value
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.
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The purpose of this study is to perform an exergy analysis of a turbojet engine combustor at different cycle parameters.
Abstract
Purpose
The purpose of this study is to perform an exergy analysis of a turbojet engine combustor at different cycle parameters.
Design/methodology/approach
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.
Findings
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.
Practical implications
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.
Social implications
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.
Originality/value
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.
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Kayhan Tajeddini, Taylan Budur, Thilini Chathurika Gamage, Ahmet Demir, Halil Zaim and Ramazan Topal
This paper investigates the effect of diversity management on employees' innovative work behavior (IWB) through human resource management (HRM) and affective commitment (AC).
Abstract
Purpose
This paper investigates the effect of diversity management on employees' innovative work behavior (IWB) through human resource management (HRM) and affective commitment (AC).
Design/methodology/approach
Data were collected from 358 employees of small- and medium-sized enterprises in the Kurdistan Region of Iraq. The hypothesized model has been evaluated using structural equation modeling.
Findings
Findings suggest that workforce diversity management directly and significantly affected HRM and AC. Furthermore, findings revealed that HRM significantly influenced both employees' IWB and AC, while AC had a significant positive influence on IWB. Moreover, concerning the indirect effects, AC and HRM significantly mediated the relationship between DM and employees' IWB.
Research limitations/implications
A cross-sectional single source dataset is used to evaluate the hypothesized model.
Originality/value
Grounded in the social exchange and institutional theories, this research fills the gap in the literature by addressing the “black box” of how workforce DM influences employees' IWB while examining the mediating role of employees' AC and firm HRM policies.
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Fatma Bakal, Ahmet Yapici, Muharrem Karaaslan and Oğuzhan Akgöl
The purpose of this paper is to investigate the effect of doping element on the microwave absorption performance of hexagonal nano boron nitride (h-nBN)-reinforced basalt fabric…
Abstract
Purpose
The purpose of this paper is to investigate the effect of doping element on the microwave absorption performance of hexagonal nano boron nitride (h-nBN)-reinforced basalt fabric (BF)/epoxy composites. A new type of hybrid composite that will be produced by the use of boron nitride as an additive that leads to increased radar absorption capability will be developed and a new material that can be used in aeronautical radar applications.
Design/methodology/approach
This study is focused on the microwave absorption properties of h-nBN doped basalt fabric-reinforced epoxy composites. Basalt fabric (BF)/epoxy composites (pure composites) and the BF/h-nBN (1 Wt.% h-nBN doped composites) hybrid composites were fabricated by vacuum infusion method. Phase identification of the composites were performed using X-ray diffraction (XRD), the 2θ scan range was from 10 to 60 with the scanning speed of 3°/min and surface morphologies of the composites were investigated using scanning electron microscopy (SEM). Microwave properties of samples were investigated through transmission/reflection measurements in Agilent brand 2-Port PNA-L Network Analyzer in the frequency range of 3–18 GHz. The prepared sample is positioned between two horn antennas with and without metal plate.
Findings
Experimental results show that h-nBN doped composite was synthesized successfully and the produced hexagonal nano boron nitride-added fiber laminated composite material has good absorption behavior when they are used with metallic sheets and good for isolation applications at many points in the 3–18 GHz band.
Originality/value
This paper will contribute to the literature on the use of basalt fabric, which are new types of fibers, and hexagonal nano boron nitride and the effects of boron nitride on radar absorption properties of composite material. It presents detail characterization of each composite by using XRD and scanning electron microscopy.
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The purpose of this study is to analyze the impacts of the COVID-19 pandemic on the performance of companies using a hybrid Multi-Criteria Decision-Making (MCDM) approach…
Abstract
Purpose
The purpose of this study is to analyze the impacts of the COVID-19 pandemic on the performance of companies using a hybrid Multi-Criteria Decision-Making (MCDM) approach. Specifically, the study examines Türkiye’s Top 500 Industrial Enterprises to analyze their performance before and during the pandemic, and to capture their performance in determining investment and production strategy.
Design/methodology/approach
To achieve the study’s objectives, the Fuzzy Best-Worst Method (F-BWM) was used to obtain importance levels of performance indicators, decreasing the vagueness in experts’ decision-making preferences. The Measurement Alternatives and Ranking According to Compromise Solution (MARCOS) method was used to rank enterprises based on their performance.
Findings
The COVID-19 pandemic has clearly had a substantial impact on the performance of Türkiye’s top 500 industrial enterprises. While some companies suffered decreased sales, others reported that their revenues increased or remained constant during the outbreak. The results reveal that the pandemic caused a shift in the initial ranking outcomes for the first two enterprises.
Research limitations/implications
The study’s limitations include the sample size and the time period under consideration, which may have an impact on the generalizability of the findings.
Practical implications
Decision-makers’ investment, employment and operational decisions were influenced by the impact of the COVID-19 pandemic. The results provide insights for decision-makers on how to achieve higher growth and performance under the pressure of the pandemic.
Social implications
The study’s practical consequences help decision-makers understand how to attain higher growth and performance in the face of the epidemic.
Originality/value
The originality of this study lies in using a hybrid MCDM approach to examine the impact of the COVID-19 pandemic on company performance. A hybrid MCDM approach is proposed to help decision-makers make the best possible investment and implementation decisions.