Fernando Tejero, David MacManus, Josep Hueso-Rebassa, Francisco Sanchez-Moreno, Ioannis Goulos and Christopher Sheaf
Aerodynamic shape optimisation is complex because of the high dimensionality of the problem, the associated non-linearity and its large computational cost. These three aspects…
Abstract
Purpose
Aerodynamic shape optimisation is complex because of the high dimensionality of the problem, the associated non-linearity and its large computational cost. These three aspects have an impact on the overall time of the design process. To overcome these challenges, this paper aims to develop a method for transonic aerodynamic design with dimensionality reduction and multifidelity techniques.
Design/methodology/approach
The developed methodology is used for the optimisation of an installed civil ultra-high bypass ratio aero-engine nacelle. As such, the effects of airframe-engine integration are considered during the optimisation routine. The active subspace method is applied to reduce the dimensionality of the problem from 32 to 2 design variables with a database compiled with Euler computational fluid dynamics (CFD) calculations. In the reduced dimensional space, a co-Kriging model is built to combine Euler lower-fidelity and Reynolds-averaged Navier stokes higher-fidelity CFD evaluations.
Findings
Relative to a baseline aero-engine nacelle derived from an isolated optimisation process, the proposed method yielded a non-axisymmetric nacelle configuration with an increment in net vehicle force of 0.65% of the nominal standard net thrust.
Originality/value
This work investigates the viability of CFD optimisation through a combination of dimensionality reduction and multifidelity method and demonstrates that the developed methodology enables the optimisation of complex aerodynamic problems.
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Francisco Sánchez-Moreno, David MacManus, Fernando Tejero and Christopher Sheaf
Aerodynamic shape optimisation is a complex problem usually governed by transonic non-linear aerodynamics, a high dimensional design space and high computational cost…
Abstract
Purpose
Aerodynamic shape optimisation is a complex problem usually governed by transonic non-linear aerodynamics, a high dimensional design space and high computational cost. Consequently, the use of a numerical simulation approach can become prohibitive for some applications. This paper aims to propose a computationally efficient multi-fidelity method for the optimisation of two-dimensional axisymmetric aero-engine nacelles.
Design/methodology/approach
The nacelle optimisation approach combines a gradient-free algorithm with a multi-fidelity surrogate model. Machine learning based on artificial neural networks (ANN) is used as the modelling technique because of its ability to handle non-linear behaviour. The multi-fidelity method combines Reynolds-averaged Navier Stokes and Euler CFD calculations as high- and low-fidelity, respectively.
Findings
Ratios of low- and high-fidelity training samples to degrees of freedom of nLF/nDOFs = 50 and nHF/nDOFs = 12.5 provided a surrogate model with a root mean squared error less than 5% and a similar convergence to the optimal design space when compared with the equivalent CFD-in-the-loop optimisation. Similar nacelle geometries and aerodynamic flow topologies were obtained for down-selected designs with a reduction of 92% in the computational cost. This highlights the potential benefits of this multi-fidelity approach for aerodynamic optimisation within a preliminary design stage.
Originality/value
The application of a multi-fidelity technique based on ANN to the aerodynamic shape optimisation problem of isolated nacelles is the key novelty of this work. The multi-fidelity aspect of the method advances current practices based on single-fidelity surrogate models and offers further reductions in computational cost to meet industrial design timescales. Additionally, guidelines in terms of low- and high-fidelity sample sizes relative to the number of design variables have been established.
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Francisco Sánchez-Moreno, David MacManus, Fernando Tejero, Josep Hueso-Rebassa and Christopher Sheaf
The decrease in specific thrust achieved by Ultra-High Bypass Ratio (UHBPR) aero-engines allows for a reduction in specific fuel consumption. However, the typical associated…
Abstract
Purpose
The decrease in specific thrust achieved by Ultra-High Bypass Ratio (UHBPR) aero-engines allows for a reduction in specific fuel consumption. However, the typical associated larger fan size might increase the nacelle drag, weight and the detrimental interference effects with the airframe. Consequently, the benefits from the new UHBPR aero-engine cycle may be eroded. This paper aims to evaluate the potential improvement in the aerodynamic performance of compact nacelles for installed aero-engine configuration.
Design/methodology/approach
Drooped and scarfed non-axisymmetric compact and conventional nacelle designs were down selected from a multi-point CFD-based optimisation. These were computationally assessed at a set of installation positions on a contemporary wide-body, twin-engine transonic aircraft. Both cruise and off-design conditions were evaluated. A thrust and drag accounting method was applied to evaluate different aircraft, powerplant and nacelle performance metrics.
Findings
The aircraft with the compact nacelle configuration installed at a typical installation position provided a reduction in aircraft cruise fuel consumption of 0.44% relative to the conventional architecture. However, at the same installation position, the compact design exhibits a large flow separation at windmilling conditions that is translated into an overall aircraft drag penalty of approximately 5.6% of the standard cruise net thrust. Additionally, the interference effects of a compact nacelle are more sensitive to deviations in mass flow capture ratio (MFCR) from the nominal windmilling diversion condition.
Originality/value
This work provides a comprehensive analysis of not only the performance but also the aerodynamics at an aircraft level of compact nacelles compared to conventional configurations for a range of installations positions at cruise. Additionally, the engine-airframe integration aerodynamics is assessed at an off-design windmilling condition which constitutes a key novelty of this paper.
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Luana Lavagnoli Moreira, Rafael Rezende Novais, Dimaghi Schwamback and Salomão Martins de Carvalho Júnior
The most common methodology to estimate erosivity is using rainfall data obtained from rain monitoring stations. However, the quality of this estimation may be compromised due to…
Abstract
Purpose
The most common methodology to estimate erosivity is using rainfall data obtained from rain monitoring stations. However, the quality of this estimation may be compromised due to low density, operational problems and maintenance cost of rainfall monitoring stations, common problem encountered in developing countries such as Brazil. The objective of this study was to evaluate the applicability of pluviometric data obtained by TRMM satellite images for the spatiotemporal characterization of erosivity in the state of Espírito Santo (Brazil).
Design/methodology/approach
For this, rainfall data and annual and monthly erosivities of 71 rainfall stations were statistically compared with those from TRMM images.
Findings
For this, rainfall data and annual and monthly erosivities of 71 rainfall stations were statistically compared with those from TRMM images. The estimate proved that TRMM is efficient since the NSE values were higher than 0.70 and the coefficient of determination was higher than 0.77 for monthly and annual erosivities, but in most months and yearly, erosivity was overestimated.
Practical implications
The use of satellite images to estimate rainfall allowed the spatial representation over time (months) of the oscillating degree of erosivity in the state of Espírito Santo (Brazil). The spatialization may provide an identification of areas and periods in which are essential for the implementation of land use management in order to minimize environmental problems related to soil loss.
Originality/value
The technique applied may be an alternative to overcome common problems on rainfall monitoring station, such as low density, low data reliability, high manutention and maintenance cost and operational problems.
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Mercedes Mareque, Elena de Prada and Margarita Pino Juste
This study aims to delve deep into the differences observed in leadership acquisition and development between men and women and analyse the impact of certain extra-curricular…
Abstract
Purpose
This study aims to delve deep into the differences observed in leadership acquisition and development between men and women and analyse the impact of certain extra-curricular activities demonstrated to influence leadership acquisition. With this evidence, this study intends to detect areas that require deeper analysis and suggest actions to redress the balance and promote a more egalitarian leadership in education in both teaching and management positions.
Design/methodology/approach
Accidental, as opposed to random, sampling was used via a cross-curricular study with a quasi-experimental design. The participants in this study were 335 teacher training students in Spanish universities. The Teamwork Skills Questionnaire was used to evaluate leadership and a self-assessment questionnaire to measure extracurricular activities.
Findings
Female students score lower in leadership skills and are engaged in fewer activities associated with successful leadership skills development. Very few students receive any training on leadership, with even fewer female than male students. Furthermore, the practice of certain extra-curricular activities can boost leadership skills. It has also been noted that these activities are carried out in different ways, depending on student gender.
Originality/value
This study has two points of focus: the level of leadership among education students, differentiating between male and female students, and the impact of certain extra-curricular activities carried out during the academic year, which have proven to have a considerable effect on the development of leadership skills.
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Julián López Yáñez and Marita Sánchez Moreno
This paper seeks to point out the relationship between women leadership and their role in the transformation of university organizations, on the basis of eight case studies…
Abstract
Purpose
This paper seeks to point out the relationship between women leadership and their role in the transformation of university organizations, on the basis of eight case studies analysed in the framework of a broader research on women who occupy high‐managerial posts in Spanish universities.
Design/methodology/approach
Two of the eight cases studied are more deeply described and discussed in terms of the relationship among the organizational context in which these women leaders perform their managerial functions, the leadership styles that they deploy, as well as the transformations they promoted in critical moments of the organizations that they head.
Findings
Even though the differences in all these aspects between the two cases studied do not allow a single and homogeneous “feminine style” of management to be identified, a flexible and adaptive common orientation in terms of leadership was found, which leads one to suggest that leadership style is not a relevant issue when managing loosely coupled organizations. Furthermore, some conclusions were established about the ability of these woman managers both to read organizational culture and to drive such changes, preserving social cohesiveness and the workplace climate. To achieve this, they adopted a flexible leadership style on the basis of a wide range of power sources.
Originality/value
The findings support the idea that the loosely coupled structures characteristic of a higher education organization need “soft” ways of power management, oriented more towards informal social networks than formal issues. This allows one to discuss the innovative role that women potentially and actually play in higher education organizations.
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Rita A. Gardiner and Hayley Finn
Undertaking feminist inquiry calls for scholars to challenge the powerful hegemonic, masculinist, taken for granted values and gender injustices that continue to underpin…
Abstract
Purpose
Undertaking feminist inquiry calls for scholars to challenge the powerful hegemonic, masculinist, taken for granted values and gender injustices that continue to underpin institutional life (Wickstrom et al., 2021). A root cause of gender injustice is misogynistic and neoliberal institutional practices. Gender injustices range from micro-aggressions to workplace bullying (Mavin and Yusupova, 2021), as well as the perpetuation of sexualized and gender-based violence (GBV). The purpose of this paper is to consider the challenges with policy implementation of GBV policies. Specifically, the authors discuss the barriers three senior women leaders at one Canadian university face in their efforts to change institutional culture, with the intention of minimizing GBV on campus. By attending to the lived experiences of women leaders involved in trying to effect institutional change, the authors learn that GBV is not an unusual event. Rather, it is an everyday occurrence perpetuated by hierarchical cultures that resist those women leaders who think and act differently. Put simply, trying to lead differently is not without risk, especially for those women courageous enough to speak out against gender injustices in the workplace. The risks associated with speaking out are at the individual level (personal identity) and interactional level (social ties) (Khan et al., 2018). Furthermore, these findings suggest women leaders willing to speak out may experience isolation. Over time, this isolation can lead to a lack of support and burnout (Zumaeta, 2018).
Design/methodology/approach
Building upon the work of Ahmed (2014; 2015; 2017; 2019; 2021), this paper seeks to explicate the interconnections between gender and structural inequities in the neoliberal academy. The authors use a theoretical and methodological approach that draws upon Ahmed’s (2014) notion of “practical phenomenology.” This approach can highlight valuable insights from the experiences of those involved in the act of “doing,” which, in this case, refers to three women leaders engaged in the implementation of a GBV policy. Using this approach helps to weave theory and praxis together to comprehend the difficulties women leaders experience in putting policy into practice to enact institutional change to eradicate gender inequities.
Findings
The findings of this paper indicate the challenges women leaders in academia have in putting policy into practice. Four interconnected themes emerge: the insidious institutional roots of GBV; naming or lack thereof; pockets of resistance; and balancing contradictions. These findings also indicate that leading this type of institutional policy change requires determination and courageous action to combat organizational sexism (Ahmed, 2021). This action is not without challenges to the careers of those willing to speak out against gender injustice in the workplace.
Research limitations/implications
Research limitations are that this is a small study undertaken at one university in Canada. As such, these findings cannot be generalized. That said, learning from women leaders' practical experiences can help feminist scholars understand the difficulties in effecting institutional change, especially in regards to turning GBV policy into practice. In turn, this learning adds value to the gender and management literature.
Originality/value
This paper’s originality is twofold. First, this paper lies in the practical phenomenological approach the authors engage in to consider gender inequities relating to the difficulties of effecting institutional change in higher education institutions. Engaging in this critical approach helps to learn from the experiences of “expert knowers,” which, in this case, refers to those senior women leaders at the forefront of trying to effect institutional change by putting GBV policies into practice. Second, this paper adds to the literature critiquing how masculinist structures in higher education operate to shore up institutional sexism.