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Article
Publication date: 18 January 2016

Wenzhuo Chen, Yan Chen, Bo Li, Weiming Zhang and Ken Chen

– The purpose of this paper is to design a special automatic redundant robot painting system (RRPS), which can automatically navigate and paint in the long non-regular duct.

Abstract

Purpose

The purpose of this paper is to design a special automatic redundant robot painting system (RRPS), which can automatically navigate and paint in the long non-regular duct.

Design/methodology/approach

The RRPS is designed with three subsystems: a redundant robot, a spraying system and a control and safety system. Based on the modular design theory, the robot falls naturally into a mobile platform, a 4-DOF location mechanism and a 10-DOF manipulator. The restriction of the distance between the links and the duct axis is used to plan the trajectory of the manipulator so that it would not collide with the duct. The restriction model is constructed by minimizing the sum of the weighed distances between the duct axis and the special points.

Findings

A fully working prototype system has been developed. Test results show that the minimal distance between the robot joints and duct is 18 mm, and it can finish painting long non-regular ducts at the speed of 12.5 cm/s and the spraying distance of 16 cm. The quality of coating layers is good.

Practical implications

The RRPS was used to paint non-regular rectangular ducts, cylindrical ducts and long non-regular ducts. The feasibility of painting long non-regular duct is proved with the prototype implementation and successful test results.

Originality/value

The RRPS shows a novel solution that is based on the 14-DOF redundant robot design for painting long non-regular ducts which is used in airplane.

Details

Industrial Robot: An International Journal, vol. 43 no. 1
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 1 June 2006

Gong Hee Lee and Je Hyun Baek

To investigate the effect of aspect ratio on the quantitative analogy between developing laminar flows in orthogonally rotating straight ducts and stationary curved ducts

Abstract

Purpose

To investigate the effect of aspect ratio on the quantitative analogy between developing laminar flows in orthogonally rotating straight ducts and stationary curved ducts

Design/methodology/approach

A fractional step method is used to obtain the numerical solution of the governing equations by decoupling the solution of the momentum equations from the solution of the continuity equation. In order to clarify the similarity of the two flows, dimensionless parameters KLR and Rossby number, Ro, in a rotating straight duct were used as a set corresponding to Dean number, KLC, and curvature ratio, λ, in a stationary curved duct.

Findings

Under the condition that the aspect ratio was larger than one and that the magnitude of Ro or λ was large enough to satisfy the “asymptotic invariance property” the quantitative analogy between the two flows was established clearly.

Research limitations/implications

As the aspect ratio decreased below one, the difference between the secondary flow intensities of these two flows increased, and therefore, the analogy between the two flows was not as evident as that for the larger aspect ratios.

Practical implications

Based on this methodology, the characteristics of the developing flow in orthogonally rotating ducts of higher aspect ratio can be predicted by considering the flow in stationary curved ducts, and vice versa.

Originality/value

The results obtained in this study will suggest an optimal criterion for the application of this approach to the flow similarity analysis in rectangular ducts with arbitrary aspect ratios.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 16 no. 4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 July 1939

G.N. Patterson

AN interesting feature of modern aeroplane design is the growing use of duct systems. The low drag and heat regeneration obtainable from a cooling duct is now an…

Abstract

AN interesting feature of modern aeroplane design is the growing use of duct systems. The low drag and heat regeneration obtainable from a cooling duct is now an accomplished fact. Ventilation systems for cabin aircraft have been introduced. In the future we may see duct systems used in connexion with the control of the boundary layer. As aeroplane design is improved, new applications of duct systems continue to appear.

Details

Aircraft Engineering and Aerospace Technology, vol. 11 no. 7
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 May 2002

Gong Hee Lee and Je Hyun Baek

A numerical study of a quantitative analogy of fully developed turbulent flow in a straight square duct rotating about an axis perpendicular to that of the duct and a…

Abstract

A numerical study of a quantitative analogy of fully developed turbulent flow in a straight square duct rotating about an axis perpendicular to that of the duct and a stationary curved duct of square cross‐section was carried out. In order to compare the two flows, the dimensionless parameters KTR=Re1/4/√Ro and the Rossby number, Ro=wmdh, in the rotating straight duct flow corresponded to KTC=Re1/4/√λ and the curvature ratio, λ=R/dh, in the stationary curved duct flow, so that they had the same dynamical meaning as those parameters for fully developed laminar flow. For the large values of Ro or λ, the flow field satisfied the “asymptotic invariance property”; there were strong quantitative similarities between the two flows, such as in the flow patterns and friction factors for the same values of KTR and KTC. Based on these similarities, it is possible to predict the flow characteristics in rotating ducts by considering the flow in stationary curved ducts, and vice versa.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 12 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 16 April 2018

Eero Immonen

This paper aims to design an optimal shape for an annular S-duct, considering both energy losses and exit flow uniformity, starting from a given baseline design. Moreover…

Abstract

Purpose

This paper aims to design an optimal shape for an annular S-duct, considering both energy losses and exit flow uniformity, starting from a given baseline design. Moreover, this paper seeks to identify the design factors that affect the optimal annular S-duct designs.

Design/methodology/approach

The author has carried out computational fluid dynamic (CFD)-based shape optimization relative to five distinct numerical objectives, to understand their interrelations in optimal designs. Starting from a given baseline S-duct design, they have applied control node-induced shape deformations and high-order polynomial response surfaces for modeling the functional relationships between the shape variables and the numerical objectives. A statistical correlation analysis is carried out across the optimal designs.

Findings

The author has shown by single-objective optimization that the two typical goals in S-duct design, energy loss minimization and exit flow uniformity, are mutually contradictory. He has presented a multi-objective solution for an optimal shape, reducing the total pressure loss by 15.6 per cent and the normalized absolute radial exit velocity by 34.2 per cent relative to a baseline design. For each of the five numerical objectives, the best optimization results are obtained by using high-order polynomial models.

Research limitations/implications

The methodology is applicable to axisymmetric two-dimensional geometry models.

Originality/value

This paper applies a recently introduced shape optimization methodology to annular S-ducts, and, it is, to the author’s knowledge, the first paper to point out that the two widely studied design objectives for annular S-ducts are contradictory. This paper also addresses the value of using high-order polynomial response surface models in CFD-based shape optimization.

Details

Engineering Computations, vol. 35 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 August 2016

Lei Luo, Chenglong Wang, Lei Wang, Bengt Ake Sunden and Songtao Wang

The dimple is adopted into a pin fin wedge duct which is widely used in modern gas turbine vane cooling structure trailing edge region. The purpose of this paper is to…

Abstract

Purpose

The dimple is adopted into a pin fin wedge duct which is widely used in modern gas turbine vane cooling structure trailing edge region. The purpose of this paper is to study the effects of dimple depth and duct converging angle on the endwall heat transfer and friction factor in this pin fin wedge duct.

Design/methodology/approach

The study is carried out by using the numerical simulations. The diameter of dimples is the same as the pin fin diameter with an inline manner arrangement in relation to the pin fin. The ratio between dimple depth and dimple diameter is varied from 0 to 0.3 and the converging angle is ranging from 0° to 12.7°. The Reynolds number is between 10,000 and 50,000. Results of the endwall Nusselt number, friction factor, and flow structures are included. For convenience of comparison, the pin fin wedge duct with a converging angle of 12.7° without dimples is considered as the baseline.

Findings

It is found that the dimples can effectively enhance the endwall heat transfer due to the impingement on the dimple surface, reattachment downstream the dimple and recirculation in front of the pin fin leading edge. By increasing the converging angle, the heat transfer is also increased but with a large friction factor penalty. In addition, the heat transfer enhancement for deep depth cases is 1.57 times higher than that of the low depth case. The thermal performance indicates that the intensity of heat transfer enhancement depends upon the dimple depth and converging angle.

Originality/value

It suggests that the endwall heat transfer in a pin fin wedge duct can be increase by the adoption of dimples. The optimal dimple relative depth is 0.2 with low friction factor and high heat transfer performance.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 12 October 2012

Fotios Papadopoulos, Ioannis Valakos and Ioannis K. Nikolos

The purpose of this paper is to design an S‐duct intake for unmanned aerial vehicles (UAVs) applications with good efficiency in a wide range of operating conditions.

Abstract

Purpose

The purpose of this paper is to design an S‐duct intake for unmanned aerial vehicles (UAVs) applications with good efficiency in a wide range of operating conditions.

Design/methodology/approach

A fully‐parametric 3‐D CAD model of the intake was constructed in order to produce different intake configurations, within specific geometric constraints, and to study the influence of geometry variation on efficiency. O‐type blocking methodology was adopted in order to construct the block‐structured mesh of hexahedral elements, used in the simulations. The commercial CFD code ANSYS‐CFX was used to compute the flow field inside the flow domain of each case considered. The Reynolds averaged Navier‐Stokes (RANS) equations are discretized using an implicit, vertex‐based finite volume method, combined with the shear stress transport (SST) two‐equation turbulence model and an automatic wall treatment.

Findings

By shortening the axial length the flow separation after the first turning becomes more pronounced and the losses are increasing. For very long ducts the increased internal wall area leads to increased wall friction and, consequently, to increased loss production.

Originality/value

The adoption of Gerlach‐shaped profiles for the design of the S‐duct resulted in a low pressure loss level for the optimal shape, although more uniform distribution of total pressure losses resulted for ducts longer than the optimal one, which should be taken into account in the design process.

Details

Aircraft Engineering and Aerospace Technology, vol. 84 no. 6
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 December 1965

C.E. Tharratt

A Theoretical Approach to Assessing the Thermodynamic Process Within the Combustion Chamber of the Propulsive Duct, an Examination of the Potential of the Duct with…

Abstract

A Theoretical Approach to Assessing the Thermodynamic Process Within the Combustion Chamber of the Propulsive Duct, an Examination of the Potential of the Duct with Special Reference to the Application of Feedback and Spark Discharge Techniques. The type of valve of greatest importance to successful duct design is one which is synchronized to the pressure fluctuations within the combustion zone. Although there have been a number of proposals for mechanically linked valves (indeed the normal internal combustion engine works on this principle) and rotary valves, these have severe limitations at the higher frequencies and are generally impracticable for the application under review. This section will therefore concentrate on the mechanical reed‐type valve which, theoretically, need have only one moving part, i.e. the dynamic metal reed, and the aerodynamic valve which relies upon the interaction of two gas dynamical vibrations and has no moving mechanical parts.

Details

Aircraft Engineering and Aerospace Technology, vol. 37 no. 12
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 January 2014

Tareq Salameh and Bengt Sunden

– The aim of this paper is to study two-dimensional numerical simulations of the flow and temperature fields inside the bend (turn) part of a U-duct.

Abstract

Purpose

The aim of this paper is to study two-dimensional numerical simulations of the flow and temperature fields inside the bend (turn) part of a U-duct.

Design/methodology/approach

Several turbulence models based on two and five equations were used to solve the momentum and energy equations inside the bend (turn) part of the U-duct. For two-equation models, both the renormalization group and realizable k-ɛ turbulence models were implemented. The five-equation model used is a Reynolds stress model with different wall boundary conditions. Standard, non-equilibrium and enhanced wall functions were used in parallel with the two- and five-equation models to treat the turbulent flow near the duct walls.

Findings

Several turbulence models were used to simulate the flow and temperature fields along the bend part of a U-duct with different inlet and thermal boundary conditions. The numerical results indicate that the renormalization and realizable k-ɛ turbulence models with standard wall function treatment gave the best results when compared with experimental data obtained for similar conditions.

Research limitations/implications

For heat transfer analysis, two different thermal boundary conditions, i.e. constant wall temperature and constant heat flux at the wall are implemented. The results are calculated for Reynolds number equal 20,000.

Practical implications

The results can be used in designing heat exchangers, piping and duct systems, and internal passage cooling of gas turbine blades.

Originality/value

The numerical results obtained here concentrate on the detailed investigation of flow and temperature field at the outer wall of the bend part. Different boundary conditions at the inlet and the outer bend walls of the U-duct were applied to study how these boundary conditions affect the flow and temperature fields.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 February 1998

Masoud Rokni and Bengt Sundén

The present investigation is an extension of the authors’ previous work on ducts with different cross sections. It concerns application of turbulence models for forced…

Abstract

The present investigation is an extension of the authors’ previous work on ducts with different cross sections. It concerns application of turbulence models for forced convective heat transfer in three‐dimensional corrugated or wavy ducts. Different wavy ducts with fully developed flow and temperature fields are considered. The numerical approach is based on the finite volume technique with a non‐staggered grid arrangement. For handling the pressure‐velocity coupling the SIMPLEC‐algorithm is used. Cyclic boundary conditions are imposed in the main flow direction to achieve fully developed conditions. The non‐linear k‐ε model of Speziale with wall functions is used to calculate the turbulent stresses. The simple eddy diffusivity concept is applied to calculate the heat fluxes, but the GGDH and the WET methods are also used in some cases. The influence of the geometry parameters and comparison between different ducts are presented in terms of the friction factor and average Nusselt number. In particular the secondary velocity field and the cross sectional temperature distributions are investigated.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 8 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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