Towards a Probabilistic Preliminary Design Criterion for Buckling Critical Composite Shells

Unlined pressure tunnels were first driven by the Norwegians into hard granitic rock, which is the ideal material for this type of structure. However, the increase in demand for electric power has propelled the industry to develop projects at sites all over the world with less favourable geological conditions. The paper places emphasis on the preliminary design phase when no field measurements are available. A recent study by Rancourt (published in 2010) has investigated the spatial distribution of the minimum stress that is required to control hydraulic jacking around unlined pressure tunnels. Various surface topographic profiles including slopes, hills, and valleys; the rock cover to tunnel diameter ratio; as well as the presence of geological features such as shear zones and dykes were investigated with numerical modelling. Effective rock cover predictions are compared to those given by the well-known Norwegian design criterion, and a correction factor called cover alteration ratio (CAR) has been introduced. In this paper, a design methodology is proposed for use of CAR at the preliminary design stage in the form of a factor of safety against hydraulic jacking to be used in conjunction with the Norwegian criterion. Limitations on the use of the Norwegian criterion are highlighted.

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Analysis of Influence of Structures and Strength about Corrugated Radius of Metallic Sealing Ring

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.971-973.872 ◽

2014 ◽

Vol 971-973 ◽

pp. 872-876

Author(s):

Xiang Yu Ding ◽

Xi Chen

Keyword(s):

Mechanical Properties ◽

Finite Element ◽

Stress Distribution ◽

Design Criterion ◽

Design Criteria ◽

Preliminary Design ◽

Aero Engine ◽

Sealing Ring

In order to make the design criteria of metallic sealing rings, and improve the mechanical properties of metallic sealing rings used in aviation engine, using finite element analyzing the stress distribution of three corrugated sealing rings with different corrugated radius. Finally get a preliminary design criterion of metallic sealing rings of aero engine

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A Criterion for the Preliminary Design of High-Efficiency Tube-Axial Fans

Volume 1: Aircraft Engine; Fans and Blowers; Marine ◽

10.1115/gt2016-56960 ◽

2016 ◽

Cited By ~ 2

Author(s):

Massimo Masi ◽

Stefano Castegnaro ◽

Andrea Lazzaretto

Keyword(s):

High Efficiency ◽

Low Cost ◽

Pressure Rise ◽

Maximum Size ◽

Industrial Applications ◽

Design Criterion ◽

Preliminary Design ◽

Axial Fan ◽

Axial Fans ◽

Analytical Formulas

Tube-axial fans are widely used in industrial applications because of their compactness, simplicity, and low cost. However, the achievable fan pressure rise is generally penalised by the absence of a straightener and diffuser, and the consequent waste of tangential and axial dynamic pressures at the fan outlet. The corresponding fan efficiency drop might not comply with stringent regulations like the European Directive for energy-related products. Thus, operation ranges of high efficiency need to be clearly defined in the preliminary design phase, especially when constraints on maximum size and/or rotational speed are imposed. This paper proposes analytical formulas and charts to evaluate the efficiency of the tube-axial fan configuration (with or without tail-cone diffuser) when constraints on fan size and/or speed are additional design requirements. The analytical formulas and charts have been validated against experimental data. On this basis, a preliminary design criterion is suggested for high-efficiency tube-axial fans featuring arbitrary vortex design blades of constant swirl type. The criterion is used to design a 315 mm low-to-medium pressure tube-axial fan that is able to operate at a constant aeraulic efficiency peak of approximately 0.6 for blade positioning angles in the range 20° to 30°.

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