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Turboshaft engines usually include one centrifugal compressor due to its high-pressure ratio, stability and compactness. Many designers rely on positive raking to decrease tip gap flow and therefore losses. However recent optimization studies revealed geometries contradicting this canonic view. Hence, this paper aims to investigate how the rake angle alone can influence performance and to which extent.

A turboshaft representative impeller was chosen and altered for null and +/−30° rake angles. Menter's shear stress transport model is used for steady computational fluid dynamics simulations, sweeping the nominal speedline at various tip clearances. Backsweep distribution is identical in all cases, isolating rake influence.

Pressure ratio was lowered for the both positively and negatively raked blades, but through distinct aerodynamic mechanisms. Although the flow through the tip gap was lower for the positive rake, this is due to lower blade loading. Splitter comparison reveal that these effects are more pronounced in the radial regions.

Some of the findings may extend beyond turboshaft engines, into turbochargers, home appliances or industrial blowers. However, all extrapolations must consider specific differences between these applications. Turboshaft compressors designers can benefit from this study when setting up their free parameters and penalty functions in the early concept stages.

Only few similar studies can be found in the literature to date, none similar to turboshaft applications. Also, this impeller is designed to eliminate leading edge shocks and suction side boundary layer separation, which makes it easier to isolate the tip gap flow effects. The authors also provide a framework on which semi-empirical design equations can be further developed to incorporate rake into 1D design tools.

The purpose of this study is to suppress secondary flows and improve aerodynamic performance of a centrifugal impeller.

A multi-objective optimisation design system was described. The optimization design system was composed of a three-dimensional (3D) inverse design, multi-objective optimisation and computational fluid dynamics (CFD) analysis. First, the control parameter ΔCp for the secondary flows was derived and selected as the optimisation objective. Then, aimed at minimising ΔCp, a 3D inverse design for impellers with different blade loading distributions and blade lean angles was completed and multi-objective optimisation was conducted. Lastly, the improvement in the distribution of secondary flows and aerodynamic performance of the optimal impeller was demonstrated by CFD analysis.

The study derived the control parameter ΔCp for the secondary flows. ΔCp can indicate the distribution of secondary flows both near the blade pressure and suction surfaces. As ΔCp decreased, secondary flows decreased. The blade loading distribution with fore maximum blade loading at the shroud and aft maximum blade loading at the hub, coupled with a small negative blade lean angle, could help suppress secondary flows and improve aerodynamic efficiency.

A direct control method on internal flow field characteristic-secondary flows by optimisation design was proposed for a centrifugal impeller. The impeller optimisation design process saves time by avoiding substantial CFD sample calculations.

HIGH strength high stiffness composite materials offer the engineer a solution to many problems, and are of considerable interest to gas turbine designers. The particular mechanical problems associated with compressor rotor blades become more severe as the blade tip speeds and stage loadings increase, and in many respects composites lend themselves ideally to their solution. The advantages of using composite materials are stated, and the problems, together with possible solutions, are discussed.

NO name is said to carry a higher reputation in the design and manufacture of advanced aero engines than Rolls‐Royce. With its innovative designs and engineering skills it was only to be expected that the company would be a finalist in the Manufacturing Effectiveness Award 1984, organised by the Institution of Mechanical Engineers, on behalf of sponsors Willis Faber.

Nowadays, a large amount of data related to aero engine in various types can be created in a single day and it is very important to well organize and store these data. The paper aims to discuss this issue.

This paper puts forward the problem of data management with the fast development of aero engine and sets the compression system as an example to see the inner relationships of data from the initial design procedure to the final operation and maintenance part. There are five principles, namely digitization, accuracy, normative, integrality and validity, involved in managing the data effectively.

These data resources arranged according to the five principles can be well organized and better used.

At the end, the top design of aero engine data sharing platform is investigated and five layers including data layer, data access layer, communication layer, business logic layer and application layer are designed and presented to support the platform.

Presents a brief overview of some new concepts and research results concerning aerodynamic computation and design of jet‐propulsion engines with emphasis on turbomachinery (TM) developed in China, without any attempt to be exhaustive.

This paper aims to improve performance prediction and to acquire more detailed flow structures so as to analyze the turbulence in complex rotor-stator flow.

Hydraulic retarder as typical fluid machinery was numerically investigated by using hybrid Reynolds-averaged Navier–Stokes (RANS)/large eddy simulation (LES) models CIDDES Algebraic Wall-Modeled Large Eddy Simulation (LES) (WMLES) S-Ω and dynamic hybrid RANS/LES (DHRL). The prediction results were compared and analyzed with a RANS model shear stress transport (SST) k-omega which was a recommended choice in engineering.

The numerical results were verified by experiment and indicated that the predicted values for three hybrid turbulence models were more accurate. Then, the transient flow field was further analyzed visually in terms of turbulence statistics, Reynolds number, pressure-streamline, vortex structure and eddy viscosity ratio. The results indicated that HRL approaches could capture unsteady flow phenomena.

This study achieves both in performance prediction improvement and better flow mechanism understanding. The computational fluid dynamics (CFD) could be used instead of flow visualization to a certain extent. The improved CFD method, the fine computational grid and the reasonable simulation settings jointly enhance the application of CFD in the rotor-stator flow.

The improvement was quite encouraging compared with the reported literatures, contributing to the CFD playing a more important role in the flow machinery. DHRL provided the detailed explanation of flow transport between rotor and stator, which was not reported before. Through it, the flow mechanism can be better understood.

The purpose of this study is to explore the transient characteristics of mixed-flow pumps during startup process.

This study uses a full-flow field transient calculation method of mixed-flow pump based on a closed-loop model.

The findings show the hydraulic losses and internal flow characteristics of the piping system during the start-up process.

Large computational cost.

Improve the accuracy of current numerical simulation results in transient process of mixed-flow pump.

Simplify the setting of boundary conditions in the transient calculation.

This study aims at enhancing the performance of a 16-stage axial compressor and improving the operating stability. The adopted approaches for upgrading the compressor are artificial neural network, optimization algorithms and computational fluid dynamics.

The process starts with developing several data sets for certain 2D sections by means of training several artificial neural networks (ANNs) as surrogate models. Afterward, the trained ANNs are applied to the 3D shape optimization along with parametrization of the blade stacking line. Specifying the significant design parameters, a wide range of geometrical variations are considered by implementation of appropriate number of design variables. The optimized shapes are analyzed by applying computational fluid dynamic to obtain the best geometry.

3D optimal results show improvements, especially in the case of decreasing or elimination of near walls corner separations. In addition, in comparison with the base geometry, numerical optimization shows an increase of 1.15 per cent in total isentropic efficiency in the first four stages, which results in 0.6 per cent improvement for the whole compressor, even while keeping the rest of the stages unchanged. To evaluate the numerical results, experimental data are compared with obtained data from simulation. Based on the results, the highest absolute relative deviation between experimental and numerical static pressure is approximately 7.5 per cent.

The blades geometry of an axial compressor used in a heavy-duty gas turbine is optimized by applying artificial neural network, and the results are compared with the base geometry numerically and experimentally.

The purpose of this paper is to describe the Start Lean program, run by the Manufacturing Institute in the UK, which aims to introduce apprentices to the principles of lean manufacturing and to instil a lean way of thinking early in their careers.

Describes the course, and the improvement project realized by two apprentices at Callender Aeropart, a UK manufacturer of turbine blades for jet engines and power‐transmission applications.

Reveals how the apprentices reorganized a recycling station for cutting‐tool inserts as part of a series of improvements that have the potential to save the business thousands of pounds a year.

Argues that the apprentices are now a lot more involved in day‐to‐day operations and are much more willing to challenge and ask questions.

Explains that the programme has improved the apprentices' knowledge and appreciation of what the company is trying to do, as well as boosting their confidence.