Search results

The assembly sequence in the product assembly process has effect on the final product quality. To solve the assembly sequence optimization problem, such as rotor blade assembly sequence optimization, this paper proposes a small world networks-based genetic algorithm (SWN_GA) to solve the assembly sequence optimization problem. The proposed approach SWN_GA consists of a combination between the standard Genetic Algorithm and the NW Small World Networks.

The selection operation and the crossover operation are improved in this paper. The selection operation remains the elite individuals that have greater fitness than average fitness and reselects the individuals that have smaller fitness than average fitness. The crossover operation combines the NW Small World Networks to select the crossover individuals and calculate the crossover probability.

In this paper, SWN_GA is used to optimize the assembly sequence of steam turbine rotor blades, and the SWN_GA was compared with standard GA and PSO algorithm in a simulation experiment. The simulation results show that SWN_GA cannot only find a better assembly sequence which have lower rotor imbalance, but also has a faster convergence rate.

Finally, an experiment about the assembly of a steam turbine rotor is conducted, and SWN_GA is applied to optimize the blades assembly sequence. The feasibility and effectiveness of SWN_GA are verified through the experimental result.

A fluid‐directing blade for turbomachincs and the like, said blade having fluid‐directing faces and comprising a number of physically united laminae each having extension in the directions lengthwise of the blade and from face to face of the blade, the edges of the laminae constituting elements of the fluid directing faces of the blade, some of said laminae, constituting a first set, extending unbroken from face to face of the blade, and others of said laminae, constituting a second set, defining openings through the centres of said other laminae extending lengthwise of the blade from end to end thereof providing passages extending longitudinally of the blade from end to end thereof, the laminae of the two sets alternating chordwise of the blade.

This paper gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The bibliography at the end of the paper contains more than 1330 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1999–2002.

This paper presents a versatile and economical knowledge‐based assembly design of blade and shell assemblies by employing behavioral modeling concepts. Behavioral modeling is a new generation CAD concept aimed at achieving ultimately optimum results with the efforts made in the early stage of the product development cycle. As a result, the assembly process of any odd‐configured parts such as torque converter blades, can be accurately planned, and made adaptable to all potential in‐process alterations due to either changes of components design or that of the assembly kinematics. Optimum assembly design is achieved when the volumetric interference meets a desired value based on an expert's determination. Experimental verification of the proposed optimum assembly design conducted in Luk, Inc. with two different blades' assemblies demonstrates satisfactory results.

The purpose of the paper is to present component matching and off-design calculations using generic components maps.

Multi objective hybrid optimization code is integrated with turbojet function code. Both codes are developed for the research study. Initially, methodology is applied on a numerical propulsion system simulation (NPSS) example engine cycle calculations. Effect of matching constants are shown. Later, component matching and application is done on JetCat engine. Calculations are compared with measured test data. And additional operating conditions are calculated using the matched component constants.

Obtained matching constants provided very good results with NPSS example and also JetCat test measurements. Optimization algorithm is practical for turbojet engine component matching and off-design calculations. Off-design matching provides information about the turbine and exhaust areas of an unknown turbine engine. Thus it is possible to perform off design calculations at various operating conditions. Finding detailed turbine maps is difficult than finding compressor maps. In that case characteristic turbine curve may be a good alternative.

Selected component maps and the target engine components should be similar characteristics. For a one/two stage turbine, characteristic curves can be applied. Validation should be extended on different type of compressor and turbines.

Operators and researchers usually need more information about the available turbojet engines for increasing the effective usage. Generally, manufacturers do not provide such detailed information to public. This study introduces an alternative methodology for engine modeling by using generic component maps and thus obtaining information for off-design calculations. User is flexible for selecting/scaling the compressor and turbine maps.

A hybrid optimization code is used as a new approach. It can be used with other engine functions; for instance functions corresponding to turboshaft or turbofan engines, by modifying the engine function. Number of input parameters and objective functions can be modified accordingly.

Just as with conventional electrical cables, signals passed down optical fibres will not reach their destination if a break or improper connection is present in the fibre optic cable. Now that optical fibres are widely used in defence and communications, accurate methods of precisely locating breaks have become extremely important.

IT is nearly fifteen years since the introduction into civil operations of the Dart turboprop in the Vickers Viscount and the Ghost turbojet in the dc Havilland Comet. For many years it was thought that the turboprop would remain dominant in the short and medium haul classes, but the continued demand for higher cruising speeds and the passenger appeal of the jet have been largely responsible for the turboprop aircraft being superseded by the new generation of turbofan aircraft.

AT the end of the war in Europe, Germany had two aircraft jet engines in operational use; the Junkers Jumo 004, which has already been described, and the BMW 003 which forms the subject of this article. Compared with the Junkers 004 the BMW engine can be described as having gone one stage further in the development of the axial compressor engine, but production figures were not as great as those of the Junkers. Several hundred had been built, mainly for the Heinkel He 162 Volksjäger—the high‐speed fighter with the engine mounted over the fuselage. The engines made in the 003 series are the 003‐A0, ‐Al, ‐A2, ‐E1 and ‐E2. These are all similar and have much the same performance. The latest in this series, the 003‐A2, is shown in fig. 1, and although production was planned on a large scale, only a few of this type were actually made.

Fundamentally, it is advantageous to operate an aeroengine's thermodynamic cycle at as high a turbine entry temperature as practical for the current metallurgical limits of the turbine blades in order to achieve peak cycle efficiency and thus lower specific fuel consumption. However, achieving the highest possible turbine entry temperature requires accurate knowledge of the turbine blade temperatures for control purposes to prolong component life as frequent excursions beyond the design limits of the blades can severely reduce their service life. The optical pyrometry technique represents the best method for providing this crucial temperature data needed for blade condition‐based monitoring. This paper presents the general operating principles, system aspects and design considerations for the application of the optical pyrometer instrument for inflight service use on gas turbine aeroengines.