Search results

The paper aims to develop an efficient data-driven modeling approach for the hydroelastic analysis of a semi-circular pipe conveying fluid with elastic end supports. Besides the structural displacement-dependent unsteady fluid force, the steady one related to structural initial configuration and the variable structural parameters (i.e. the variable support stiffness) are considered in the modeling.

The steady fluid force is treated as a pipe preload, and the elastically supported pipe-fluid model is dealt with as a prestressed hydroelastic system with variable parameters. To avoid repeated numerical simulations caused by parameter variation, structural and hydrodynamic reduced-order models (ROMs) instead of conventional computational structural dynamics (CSD) and computational fluid dynamics (CFD) solvers are utilized to produce data for the update of the structural, hydrodynamic and hydroelastic state-space equations. Radial basis function neural network (RBFNN), autoregressive with exogenous input (ARX) model as well as proper orthogonal decomposition (POD) algorithm are applied to modeling these two ROMs, and a hybrid framework is proposed to incorporate them.

The proposed approach is validated by comparing its predictions with theoretical solutions. When the steady fluid force is absent, the predictions agree well with the “inextensible theory”. The pipe always loses its stability via out-of-plane divergence first, regardless of the support stiffness. However, when steady fluid force is considered, the pipe remains stable throughout as flow speed increases, consistent with the “extensible theory”. These results not only verify the accuracy of the present modeling method but also indicate that the steady fluid force, rather than the extensibility of the pipe, is the leading factor for the differences between the in- and extensible theories.

The steady fluid force and the variable structural parameters are considered in the data-driven modeling of a hydroelastic system. Since there are no special restrictions on structural configuration, steady flow pattern and variable structural parameters, the proposed approach has strong portability and great potential application for other hydroelastic problems.

This aircraft, or more exactly this integrated weapons system, is undoubtedly of major importance to both the British aircraft industry and the Royal Air Force. It is beyond question the most exacting project which the British industry has undertaken and as such has demanded adoption of the latest techniques, materials, equipment and management procedures as well as pursuit of research and development programmes on an unprecedented scale. In terms of air power, this system represents a substantial advance on any comparable aircraft or system currently in service and will give the Royal Air Force a strike and reconnaissance capability at high and low level which is possibly unmatched by any other air force in the world. The design philosophy of the TSR‐2 as it applies to an aircraft designed primarily for the high‐speed, low‐level strike/reconnaissance role was described in detail in the December 1963 issue of Aircraft Engineering (Ref. 1) but since that initial appraisal of the TSR‐2 was written some eleven months ago, there has been a gradual release of further information concerning the aircraft, its systems, power plant and equipment. It is the purpose of this article to bring the story up to date in that particular context, although it should be emphasized that the TSR‐2 is still subject to the strictest security embargo and it will be many years before a detailed study of the complete weapons system can be published. It is not intended to cover the same ground as the earlier article (Ref. 1) attempted but, before proceeding to detailed consideration of the systems, a brief overall description of the aircraft is given for the sake of completeness.

The value of drum heaters in the lubricating oil and grease industry is considerable, although their use in most industries employing barrels and drums is quite general. Oil companies, and their customers, who desire to effect rapid emptying of grease have, in the past, often had to employ gas heaters with their consequent fire hazards. More recently, drum heaters electrically operated and economical to run, have been marketed. The drum heater described here is just one adaption of the well‐known Stabilag Infra‐Red Heating Jackets which have very many diverse uses in industry. They are manufactured by The Stabilag Company Ltd., 1 Broad Street Buildings, Liverpool St., London, E.C.2., and a special feature is that not only can they be used merely to warm a drum so that its contents may be quickly loosened, but in addition, temperature may be raised sufficiently to melt the product in the drum if required.

The purpose of this paper is to accurately predict the cavitation performance of a cryogenic pump and reveal the influence of the inlet pressure, the surface roughness and the flow rate on the cavitation performance.

Firstly, the Zwart cavitation model was modified by considering the thermodynamic effect. Secondly, the feasibility of the modified model was validated by the cavitation test of a hydrofoil. Thirdly, the effects of the inlet pressure, the surface roughness and the flow rate on cavitation flow in the cryogenic pump were studied by using the modified cavitation model.

The modified cavitation model can predict the cavitation performance of the cryogenic pump more accurately than the Zwart cavitation model. The thermodynamic effect inhibits cavitation development to a certain extent. The higher the vapor volume fraction, the lower the pressure and the lower the temperature. At the initial stage of the cavitation, the head increases first and then decreases with the increase of the roughness. When the cavitation develops to a certain degree, the head decreases with the increase of the roughness. With the decrease of the flow rate, the hydraulic loss increases and the cavitation at the impeller intensifies.

A cavitation model considering the thermodynamic effect is proposed. The mechanism of the influence of the roughness on the performance of the cryogenic pump is revealed from two aspects. Taking the hydraulic loss as a bridge, the relationships among flow rates, vapor volume fractions, streamlines, temperatures and pressures are established.

NOBODY can win all the time. From Employer to Worker, from Reader to Editor there must always be some times when each wins and others where they lose out.

THE responsibility for materials handling methods, as for all other production methods, should be made the clear responsibility of the head of Work Study. The reasoning behind that firm conclusion is very logical. Industry in general depends for its success upon the application of some process such as machining or finishing of raw materials. Every such operation adds to its value and builds up a firm's turnover. It is therefore obvious that the more time there is devoted to conversion the less will be wasted on profitless storage or unproductive transport from one part of the works to another.