Robert Kulhánek, Zdeněk Pátek, Petr Vrchota, Pavel Procházka and Vaclav Uruba
Some recent effort showed that usage of Krueger flaps helps to maintain laminar flow in cruise flight. Such flaps are positioned higher relative to the chord to shield the leading…
Abstract
Purpose
Some recent effort showed that usage of Krueger flaps helps to maintain laminar flow in cruise flight. Such flaps are positioned higher relative to the chord to shield the leading edge from the insect contamination during take-off. The flap passes several through critical intermediate position during the deployment to its design position. The purpose of this paper is to analyse the aerodynamics.
Design/methodology/approach
To better understand such flow phenomena, the combined approach of computational fluid dynamics and experimental methods were used. Flow simulation was performed with in-house finite volume Navier–Stokes solver in fully turbulent unsteady RANS regime. The experimental data were obtained by means of force and pressure measurements and some areas of the flow field were examined with 2 C particle image velocimetry.
Findings
The airfoil with flap in critical position has a very limited maximum lift coefficient. The maximum achievable lift coefficient during the deployment is significantly affected by the vertical position of the trailing edge of the flap. The most unfavourable position during the deployment is not the flap perpendicular to the chord, but the flap inclined closer to it is the retracted position.
Research limitations/implications
The flap movement was not simulated either in the simulation or in the experiment. Only intermediate static positions were examined.
Practical implications
A better understanding of aerodynamic phenomena connected with the deployment of a Krueger flap can contribute to the simpler and lighter of kinematics and also to decrease time-to-market.
Originality/value
Limited experimental and computational results of Krueger flap in critical positions during the deployment are published in the literature.
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Keywords
Srinivasan Raghavan, Jan Dzugan, Sylwia Rzepa, Pavel Podany, Norman Soh, Lim Jia Hao and Niaz Khan
This study aims to investigate the effect of the wall thickness, deposition orientation and two different post-processing methods on the local mechanical properties and…
Abstract
Purpose
This study aims to investigate the effect of the wall thickness, deposition orientation and two different post-processing methods on the local mechanical properties and microstructure of additively manufactured parts made of maraging steel. In order to examine the local properties of the build, miniaturized testing specimens were employed. Before application of small-sized specimens, their performance was verified.
Design/methodology/approach
The investigation was composed of two stages. As first, the part thickness, specimen size and orientation were studied on a laser-powder bed fusion (L-PBF) platform with deposited walls of various thicknesses made of maraging steel. Subsequently, the influence of different heat-treatment methods was investigated on the final product, i.e. impellers. The miniaturized and standard tensile tests were performed to investigate the local mechanical properties. The porosity, microstructures and fracture surfaces were analysed by X-ray-computed tomography, X-ray diffraction and scanning electron microscopy with electron backscatter diffraction.
Findings
The results revealed good agreement between the values provided by miniaturized and standard specimens. The thinnest parts produced had the largest pores and the highest scatter of elongation values. In these cases, also the sub-contour porosity was observed. Part thickness affected pores’ size and results repeatability but not total porosity. The two-step heat-treatment (solutionizing and age-hardening) exhibited the highest yield and ultimate tensile strength.
Practical implications
The microstructure and local mechanical properties were studied on L-PBF platform with deposited walls of various thicknesses. Subsequently, a detailed analysis was conducted on real components (impellers) made of maraging steel, commonly used in tooling, automotive and aerospace industries.
Originality/value
The broadly understood quality of manufactured parts is crucial for their reliable and long-lasting operation. The findings presented in the manuscript allow the readers better understanding of the connection between deposition parameters, post-processing, microstructure and mechanical performance of additive manufacturing-processed parts.
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Reasonable remuneration of employee inventions is a controversial issue causing court litigations among employees and employers in many countries. The paper aims to shed light on…
Abstract
Purpose
Reasonable remuneration of employee inventions is a controversial issue causing court litigations among employees and employers in many countries. The paper aims to shed light on the missing economic interpretation of the reasonable remuneration of employee inventions. Specifically, it focuses on the concept of “reasonability” at the issue.
Design/methodology/approach
In an empirical qualitative multiple case-study setting, the paper explores inductively Czech corporate employee inventors' remuneration systems, using typological analysis and M. Weber's interpretative theoretical construct of “ideal type.”
Findings
At the first level, reasonability is a function of multi-amount rewarding, a certain level of total remuneration and identifiable benefits being a decisive factor. Additionally, the reasonability is conceptualised as a function of two dimensions – timing/risk and benefit–reward relation. At the second level, the reasonability is interpreted as a concept balancing seven points of view: timing, materiality, equity, risk management, transparency, system costs and exactness. At the third level, the paper offers an optimal remuneration system like the one that optimises developed seven-criterion framework.
Research limitations/implications
Even if analysed within one-country and nine-company context, the insights are generalisable across a broader sample of countries with statutory rules for employee inventions. Studying more cases may enrich the findings. The findings are based merely on a rational perspective and do not deal with psychological aspects of employees.
Practical implications
The results may be helpful for intellectual property or R&D managers in building or reorganising employee invention remuneration systems within corporations. The developed seven-criteria model can serve as a discussion framework; the suggested optimal system as a reference point. The results may serve as well to consultants, judges or other parties involved in currently growing employee–employer controversies and litigations. The analysis may fuel public policy decisions, too.
Originality/value
The paper brings unique and detailed empirical insights into the issue of employee inventions. It offers a complex multi-perspective (employee/employer) framework through which the reasonability can be discussed and suggests an optimal system, which can serve as a reference point.