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Article
Publication date: 2 October 2017

Hui Quan, Baiheng Fu, Rennian Li, Guangxian Li, Zhengjie Zhang and Jin Li

To analyze the work principle and capacity of energy conversion in each segment of profile lines, the energy transfer from impeller to transmission medium is separated…

Abstract

Purpose

To analyze the work principle and capacity of energy conversion in each segment of profile lines, the energy transfer from impeller to transmission medium is separated into head coefficient and load coefficient to analyze the energy transfer process. The concepts of airfoil lift coefficient and drag coefficient are used; the third manifestation of the Euler equations is used as well.

Design/methodology/approach

The numerical simulation of energy conversion mechanism based on load criteria of vane airfoil has been established in screw centrifugal pump to explain its energy conversion mechanism in an impeller. Upon this basis, the velocity and pressure along the entire blade are investigated through the numerical simulation of internal solid–liquid flow in the pump. The energy conversion process under load criteria in the blade airfoil has also been obtained.

Findings

The research suggests that the mathematical model of energy conversion mechanism based on the load criteria of the vane airfoil is reliable in the screw centrifugal pump. The screw centrifugal blade has twice or even several times the wrap angle than the ordinary centrifugal blade. It is a large wrap angle that forms the unique flow channel which lays the foundation for solid particles to pass smoothly and for soft energy conversion. At the same time, load distribution along the profile line on the long-screw centrifugal blade is an important factor affecting the energy conversion efficiency of the impeller.

Originality/value

The quantitative analysis method of energy in the screw centrifugal pump can help the pump designer improve certain features of the pump and shorten the research cycle.

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Article
Publication date: 5 October 2015

Junting Xiang, Jorg Uwe Schlüter and Fei Duan

– This paper aims to validate and analyse the NASA35 axial compressor performance based on a numerical approach.

Abstract

Purpose

This paper aims to validate and analyse the NASA35 axial compressor performance based on a numerical approach.

Design/methodology/approach

Knowledge about flow property change during compressor operation at high and relatively low speed is still limited. This work provides a numerical approach to address these problems. Validation of numerical methods is proposed to generate confidence the numerical approach adopted, and after that, analysis of compressor performance at different operation conditions is carried out.

Findings

The numerical methods proposed are proved capable in predicting compressor performance. Changes of flow property during compressor operation are discussed and explained.

Research limitations/implications

The current numerical work is carried out based on the first stage of the NASA35 axial compressor, where the interactive effects from adjacent stage are not counted in. Furthermore, the steady-state simulation enforces an averaging of flow at rotor-stator interface, where the transient rotor-stator interaction is removed.

Practical implications

This work validates the numerical methods used in the prediction of NASA35 axial compressor performance, and a similar numerical approach can be used for other turbomachinery simulation cases.

Originality/value

This work reinforces the understanding of axial compressor operation and provides reliable results for further investigation of a similar type of compressor. In addition, details of flow field within the NASA35 compressor during operation are given and explained which experiments still have difficult to achieve.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 87 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 1 June 2005

Yao Zheng, Liu Gao‐Lian and Wu Xiao‐Jiang

Provides two hybrid methods for the aerodynamic design of cascade profiles, of which the design constraints are the combination of aerodynamic and geometric conditions.

Abstract

Purpose

Provides two hybrid methods for the aerodynamic design of cascade profiles, of which the design constraints are the combination of aerodynamic and geometric conditions.

Design/methodology/approach

In the first method, the design constrain is composed of the velocity (or pressure) distribution on part of the blade surface and the geometry of the rest part. In the second method, the aerodynamic load distribution, i.e. the pressure difference between the suction and pressure surfaces, and the blade thickness distribution are employed as the design constrain. These constraints, together with all the other boundary conditions, are involved in the stationary conditions of a variational principle. The solution domain, i.e. the blade‐to‐blade passage, is transformed into a square in the image plane, while the blade contour is projected to a straight line; thus, the difficulty caused by the unknown geometry of profile is avoided. Finite element method is employed to produce the calculation code.

Findings

Applications show the accuracy and the flexibility of the two methods, which can satisfy the different needs from blade design. Finally, the possibility of combining the hybrid methods with the through‐flow method is discussed, which would develop the present methods to three‐dimensional design of cascades.

Research limitations/implications

The design methods are limited to frictionless flow.

Practical implications

A design software of cascade profiles based on this method has been developed, and will be provided to the engineering users for cascade design.

Originality/value

The hybrid methods developed in this paper can satisfy the demands from different aspects of engineering designs: aerodynamics, strength, manufacture, etc.

Details

Aircraft Engineering and Aerospace Technology, vol. 77 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 1 June 1955

P.R. Payne

In‐plane vibration of a balanced helicopter rotor is caused by variations with azimuth of the in‐plane forces acting on individual blades. These forces may be summarized…

Abstract

In‐plane vibration of a balanced helicopter rotor is caused by variations with azimuth of the in‐plane forces acting on individual blades. These forces may be summarized under three headings: ‘Induced forces’ caused by the inclination of elemental lift vectors relative to the axis of rotation. ‘Profile drag forces’: variations are caused by changes with azimuth angle of the angle and airspeed of the individual blade elements. ‘Coriolis forces’, which are caused by blade flapping, which brings about a variation of blade moment of inertia about the axis of rotation. Equations are developed in this paper for the resultant hub force due to each of these forces, on the assumptions of small flapping hinge offset. It is assumed that blades are linearly twisted and tapered, an assumption which in practice can be applied to any normal rotor. It is shown that by suitably inclining the mechanical axis it is possible to balance out the worst induced and profile drag vibrations by the coriolis one, which can be made to have opposite sign. If the mechanical axis is fixed in the fuselage, this suppression is fully effective for one flight condition only. In multi‐rotor helicopters, vibration suppression can be extended over a much wider range by varying the fuselage attitude. The logical result of this analysis is, for single rotor helicopters, a floating mechanical axis which can be adjusted or trimmed by the pilot. This would be quite simple to do on a tip‐driven rotor, and has already been achieved with a mechanical drive on the Doman helicopter. The more important causes of vibration from an unbalanced rotor are next con‐sidered, attention here being confined principally to fully articulated rotors, which are the most difficult to balance because the drag hinges tend to magnify all in‐accuracies in finish and balance. From a brief discussion of the vertical vibration of an imperfect rotor it is shown that some contemporary methods of ‘tracking’ are fundamentally wrong. Finally the vibration due to tip‐mounted power units is described. In discussing the effect of a vibratory force on a helicopter a simple response chart is developed, and it is thought that its use could well be accepted as a simple standard for general assessment purposes. In the development of equations for vibration the following points of general technical interest are put forward: An equation for induced torque is developed which includes a number of hitherto neglected parameters. A new form of equation for mean lift coefficient of a blade is suggested. The simple Hafner criterion for flight envelopes is shown to give rise to considerable error, and the use of Eq. (28) is suggested in its place. The variation of profile torque with forward speed is given, and the increase due to ? varying round the disk is expressed as an explicit equation, thus allowing considerable improvement in the present methods of allowing for this effect.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 6
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 3 August 2010

Francis J. Quail, Thomas Scanlon and Matthew Strickland

The purpose of this paper is to present a method of rapid prototyping (RP) used in the development of a regenerative pump impeller. RP technology was used to create…

Abstract

Purpose

The purpose of this paper is to present a method of rapid prototyping (RP) used in the development of a regenerative pump impeller. RP technology was used to create complex impeller blade profiles for testing as part of a regenerative pump optimisation process. Regenerative pumps are the subject of increased interest in industry.

Design/methodology/approach

Ten modified impeller blade profiles, relative to the standard radial configuration, were evaluated with the use of computational fluid dynamics (CFD) and experimental testing. Prototype impellers were needed for experimental validation of the CFD results. The manufacture of the complex blade profiles using conventional milling techniques is a considerable challenge for skilled machinists.

Findings

The complexity of the modified blade profiles would normally necessitate the use of expensive computer numerically controlled machining with five‐axis capability. With an impeller less than 75 mm in diameter with a maximum blade thickness of 1.3 mm, a rapid manufacturing technique enabled production of complex blade profiles that are dimensionally accurate and structurally robust enough for testing.

Research limitations/implications

As more advanced RP machines become available in the study in the coming months, e.g. selective laser sintering, the strength of the parts particularly for higher speed testing will improve and the amount of post processing operations will reduce.

Practical implications

This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture.

Originality/value

The ability to manufacture complex blade profiles that are robust enough for testing, in a rapid and cost effective manner is proving essential in the overall design optimisation process for the regenerative pump.

Details

Rapid Prototyping Journal, vol. 16 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 3 May 2016

Pawel Rokicki, Grzegorz Budzik, Krzysztof Kubiak, Tomasz Dziubek, Malgorzata Zaborniak, Bogdan Kozik, Jacek Bernaczek, Lukasz Przeszlowski and Andrzej Nowotnik

The purpose of this paper is to present coordinate measuring system possibilities in the meaning of the geometric accuracy assessment of hot zone elements in aircraft…

Abstract

Purpose

The purpose of this paper is to present coordinate measuring system possibilities in the meaning of the geometric accuracy assessment of hot zone elements in aircraft engines. The aim of the paper is to prove that this method, which uses blue light and is most sufficient and cost-saving method, can to be used in the production line for serial manufacturing of elements, for which a high level of accuracy is required.

Design/methodology/approach

The analysis of the geometric accuracy of the blades was performed using non-contact optical coordinate scanner ATOS Triple Scan II Blue Light, manufactured by GOM Company, at the Department of Mechanical Engineering, Rzeszów University of Technology. Geometric analysis was conducted for blades manufactured from different waxes (A7Fr/60 and RealWax VisiJet CPX200), thus comparing injection technique and rapid prototyping (RP) method, and for casting made of Inconel 713C nickel-based superalloy.

Findings

The analysis of the criteria for the method of blades’ measuring selection showed that the chosen system successfully met all criteria for the verification of blades’ geometry at the selected stages of the process. ATOS II optical scanner with blue light technology allows measurement almost regardless of daylight or artificial (white) light. This allows the application of the measurement system in the production cycle, thus eliminating the need to create special conditions for measurements.

Practical implications

Requirements related to the accuracy of measured values, diversity and allowable measurement time are linked with the methods of production. Modern manufacturing methods based on computer-aided design systems/manufacturing/engineering systems require a non-contact optical measurement method based on the computer-aided-based coordinate measuring technique. In case of the non-contact optical scanning method based on the ATOS GOM measuring system, time and measurement costs depend on the methodology of measurement and the possibility of its automation. This is why the presented paper has a practical impact on possibilities for the automation of geometric accuracy measurements of obtained elements in the series production line.

Social implications

The use of ATOS Triple Scan II Blue Light by GOM Company allows the reduction of cost and time of production because of the possibility of the introduction of this system in an automated production line. Additionally, the measurement of hot section blades of aircraft engines by using the blue light method is much more accurate and has implication as it impacts safety of further used manufactured elements.

Originality/value

This paper presents the possibility of using the ATOS Triple Scan II Blue Light measuring system for geometric accuracy measurements in case of hot section blades of aircraft engines. This research is original because it describes three model geometric accuracy measurements, wax model obtained using the injection technique, wax model obtained using the I RP process and casting made of Inconel 713C nickel-based superalloy.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 88 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 19 March 2020

Ryszard Szwaba, Piotr Kaczyński and Piotr Doerffer

The purpose of this paper is to study experimentally the effect of transition and also the roughness height on the flow structure of the shock wave boundary layer…

Abstract

Purpose

The purpose of this paper is to study experimentally the effect of transition and also the roughness height on the flow structure of the shock wave boundary layer interaction in the blades passage of a compressor cascade.

Design/methodology/approach

A model of a turbine compressor passage was designed and assembled in a transonic wind tunnel. In the experiment, the distributed roughness with different heights and locations was used to induce transition upstream of the shock wave.

Findings

Recommendation regarding the roughness parameters for the application depends on what is more important as goal, whether the reduction of losses or unsteadiness. In case if more important are the losses reduction, a good choice for the roughness location seems to be the one close to the shock wave position.

Research limitations/implications

The knowledge gained by this paper will enable the implementation of an effective laminar flow technology for engines in which the interaction of a laminar boundary layer with a shock wave takes place in the propulsion system and causes severe problems.

Originality/value

The paper focuses on the influence of the boundary layer transition induced by different roughness values and locations on aerodynamic performance of a compressor cascade. Very valuable results were obtained in the roughness application for the boundary layer transition control, demonstrating a positive effect in changing the nature of the interaction and also some negative influence in case of oversized roughness height, which cannot be found in the existing literature.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 19 July 2011

Wen‐Guang Li

A method for optimizing net positive suction head required of axial‐flow pumps has been proposed by the present author, which is based on the two‐dimensional potential…

Abstract

Purpose

A method for optimizing net positive suction head required of axial‐flow pumps has been proposed by the present author, which is based on the two‐dimensional potential flow model and without considering the tip gap effect. The objective of the paper is to confirm if the method is just and feasible for the case of viscous fluid flow in impellers with tip gap.

Design/methodology/approach

A series of steady, three‐dimensional, noncavitating and cavitating, turbulent, incompressible flows of water through two axial‐flow pump impellers were calculated by using CFD code Fluent. The two impellers included a reference one with constant circulation at outlet and an optimized one with variable circulation designed with the author's method and code. In computations, the throttling and unthrottling approaches were used, respectively. Comparison of hydraulic performance, averaged flow variables at the impeller inlet and exit, flow in the tip gap, flow variables on blade surfaces and suction performance between the optimized and reference impellers was made.

Findings

It was confirmed that the optimized impeller has better hydraulic and suction performances. The method for optimizing with variable flow circulation profile along blade span at the outlet to impeller is proper and practical. Additionally, an unstable regime in the head curves of two impellers is presented. In the regime, a stall occurs on the pressure side of the blade and a hysteresis exists, which causes a hysteresis‐loop.

Research limitations/implications

The effect of suction entry on flow is represented approximately by using a free‐vortex and uniform axial velocity. The diffusing component behind the impellers is not taken into account. The unsteadiness of flow is not considered, which would have a connection with stall pattern in an axial‐flow impeller.

Originality/value

The hydraulic and suction performances and flow variables of two axial‐flow pump impellers with tip clearance are obtained successfully with CFD. Stall and hysteresis as well as hysteresis‐loop in head curve are observed by using throttling and unthrottling approaches.

Details

Engineering Computations, vol. 28 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 September 1940

Ph. von Doepp

IN the majority of cases, the performance of a new airscrew design is estimated by making use of other test results, already known, and which are recalculated for the…

Abstract

IN the majority of cases, the performance of a new airscrew design is estimated by making use of other test results, already known, and which are recalculated for the particular case in question by applying the laws of similarity.

Details

Aircraft Engineering and Aerospace Technology, vol. 12 no. 9
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 2 October 2017

Marek Magdziak

The purpose of this paper was to determine the influence of a number of measured points on results of measurements of turbine blades, which are the parts of aircraft…

Abstract

Purpose

The purpose of this paper was to determine the influence of a number of measured points on results of measurements of turbine blades, which are the parts of aircraft engines. The selection of a number of points is the part of a measurement strategy in the coordinate measuring technique and determines the accuracy of measurements.

Design/methodology/approach

Numerical and experimental investigations were conducted. The measurements were simulated using different numbers of measured points. The simulated measurements were performed for the selected dispersion of measured points. The dispersion reflected the inaccuracy of a manufacturing process of the considered product and the uncertainty of measurements of curvilinear surfaces. To verify the accuracy of the numerical studies, experimental research was conducted. The real measurements were conducted using the selected coordinate measuring machine.

Findings

The gained results following the simulations can be very useful when selecting the appropriate number of measured points. The chosen number of points may be used during real measurements of turbine blades conducted on coordinate measuring machines. The results of numerical research indicate that there should be used the average radii of leading and trailing edges to increase the accuracy of measurements. The results of real coordinate measurements confirmed the results of simulation studies.

Originality/value

The main novelty of the paper is the presented methodology for determining the influence of measured points on results of measurements. The presented methodology helps the user of a coordinate measuring system select the appropriate measurement strategy of free-form surfaces applied in the aerospace industry.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

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