Andrea Andrisani, Diego Angeli and Antonio Dumas
The purpose of this paper is to define an optimal pitching profile for the blades of a cycloidal rotor which minimizes the mean power consumption for a given mean thrust of the…
Abstract
Purpose
The purpose of this paper is to define an optimal pitching profile for the blades of a cycloidal rotor which minimizes the mean power consumption for a given mean thrust of the rotor.
Design/methodology/approach
A simple analytical model of the kinematics and aerodynamics of a cycloidal rotor is defined first to obtain expressions for thrust and power depending on the pitching profile and geometrical parameters of the rotor. Then, Lagrange optimization is applied to obtain the optimal pitching schedule under hovering conditions. Finally, results of the theoretical analysis are compared with those of a two-dimensional computational fluid dynamics (CFD) model.
Findings
Results of the optimization suggest that the optimal profile is a combination of sinusoidal functions. It is shown that the adoption of the optimal pitching schedule could improve the power efficiency of the rotor by approximately 25 per cent.
Practical implications
The possibility to increase the efficiency of a cycloidal rotor by acting on its pitching schedule could be a significant factor of success for this alternative propulsion concept.
Originality/value
The present work represents the first attempt at a definition of an optimal pitching profile for a cycloidal rotor. Moreover, although being carried out on the basis of simplified analytical considerations, the present investigation sets a methodological framework which could be successfully applied to the design of similar kinds of systems.
Details
Keywords
Yasemin Besen and Michael S. Kimmel
The purpose of this paper is to provide an in‐depth understanding of the lived experience of sex discrimination from the perspective of women in the Wal‐Mart case and unravels the…
Abstract
Purpose
The purpose of this paper is to provide an in‐depth understanding of the lived experience of sex discrimination from the perspective of women in the Wal‐Mart case and unravels the daily mechanisms through which sex discrimination takes place.
Design/methodology/approach
One hundred and ten in‐depth statements from women who are current and former employees of Wal‐Mart, describing in detail their work experience, were employed as the main source of data. We have carried out a detailed content analysis of these in‐depth interviews identifying the mechanisms of sex discrimination.
Findings
Findings identify the specific mechanisms through which sex discrimination takes place. In the context of the current sex discrimination case, the paper provides a rich body of evidence in unraveling the everyday mechanisms of sex discrimination. It observes that instead of individual events, at important thresholds, sex discrimination is a result of small, everyday acts and gendered assumptions, which often appear supportive and harmless.
Research limitations/implications
The richness of the data provides the unique, empirical opportunity to observe the process in detail, but this paper focuses exclusively on the process, and the end‐results remain outside the scope of the paper.
Practical implications
The paper provides a very useful source of information and practical advice for women in the labor force in identifying the supportive, nice and harmless mechanisms and everyday experience of sex discrimination.
Originality/value
This paper exclusively focuses on the process and identifies the mechanisms of sex discrimination using a rich source of qualitative data. It offers empirical evidence in identifying the daily assumptions and everyday mechanisms of sex discrimination. Sex discrimination in the everyday lives are carried out in disguise of harmless, nice and often supportive behavior; therefore this paper offers explanations as to why many women stay in these exploitative jobs as long as they do.