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The purpose of this paper is to model radiation ovens and to propose a method capable of designing this kind of oven for the paint curing application. Providing a uniform cure condition on the body, especially bodies of complicated geometries, needs accurately‐designed ovens. An algorithm with high speed and high convergence capability is the most serious requirement for designing ovens of this kind.

In this paper, the state of the art in dynamic optimisation of radiation paint cure ovens is reviewed and a novel objective function, based on paint cure window, is proposed to be applied for designing radiation ovens. It has been shown that the proper definition of the objective function in such problems makes the mathematical model more robust and hence facilitates the convergence of the design iterations.

The computational results provide some information regarding the design space topology and show that the proposed objective function speeds up the convergence of the design procedure by an order of magnitude as compared to the currently used industrial‐standard objective function.

Determination of curing condition is an important requirement for designing a new oven or changing the working condition of an existing oven. In this research, a practical method is proposed for improving design procedure of cure ovens to make the method both time and cost efficient. The method is specifically implemented on paint cure ovens.

The quality of cured paint is usually a prominent issue that directly takes influence from the curing condition of ovens. For the complex geometries of curing body in commonly designed ovens, some areas are not properly cured or may be burnt. This issue is a significant defect in coating industry. Designing ovens with the proposed method in this paper guaranties the provided curing condition by the oven and therefore the curing quality.

This paper aims to assess the feasibility of additively manufactured wind tunnel models. The additively manufactured model was used to validate a computational framework allowing the evaluation of the performance of five wing models.

An optimized fighter wing was additively manufactured and tested in a low-speed wind tunnel to obtain the aerodynamic coefficients and deflections at different speeds and angles of attack. The flexible wing model with optimized curvilinear spars and ribs was used to validate a finite element framework that was used to study the aeroelastic performance of five wing models. As a computationally efficient optimization method, homogenization-based topology optimization was used to generate four different lattice internal structures for the wing in this study. The efficiency of the spline-based optimization used for the spar-rib model and the lattice-based optimization used for the other four wings were compared.

The aerodynamic loads and displacements obtained experimentally and computationally were in good agreement, proving that additive manufacture can be used to create complex accurate models. The study also shows the efficiency of the homogenization-based topology optimization framework in generating designs with superior stiffness.

To the best of the authors’ knowledge, this is the first time a wing model with curvilinear spars and ribs was additively manufactured as a single piece and tested in a wind tunnel. This research also demonstrates the efficiency of homogenization-based topology optimization in generating enhanced models of different complexity.

This paper aims to investigate the effect of post-processing techniques on dimensional accuracy of laser sintering (LS) of Nylon and Alumide^® and fused deposition modelling (FDM) of acrylonitrile butadiene styrene (ABS) materials.

Additive manufacturing (AM) of test pieces using LS of Nylon and Alumide^® powders, as well as the FDM of ABS materials, were first conducted. Next, post-processing of the test pieces involved tumbling, shot peening, hand finishing, spray painting, CNC machining and chemical treatment. Touch probe scanning of the test pieces was undertaken to assess the dimensional deviation, followed by statistical analysis using Chi-square and Z-tests.

The deviation ranges of the original built parts with those being subjected to tumbling, shot peening, hand finishing, spray painting, CNC machining or chemical treatment were found to be different. Despite the rounding of sharp corners and the removal of small protrusions, the dimensional accuracy of relatively wide surfaces of Nylon or Alumide^® test pieces were not significantly affected by the tumbling or shot peening processes. The immersion of ABS test pieces into an acetone bath produced excellent dimensional accuracy.

Only Nylon PA2200 and Alumide^® processed through LS and ABS P400 processed through FDM were investigated. Future work could also examine other materials and using parts produced with other AM processes.

The service bureaus that produce prototypes and end-use functional parts through AM will be able to apply the findings of this investigation.

This research has outlined the differences of post-processing techniques such as tumbling, shot peening, hand finishing, spray painting, CNC machining and chemical treatment. The paper discusses the advantages and disadvantages of each of those methods and suggests that the immersion of ABS test pieces into an acetone bath produced excellent dimensional accuracy.

The purpose of this paper is to improve the lattice Boltzmann method’s ability to simulate a microflow under constant heat flux.

Develop the thermal lattice Boltzmann method based on double population of hydrodynamic and thermal distribution functions.

The buoyancy forces, caused by gravity, can change the hydrodynamic properties of the flow. As a result, the gravity term was included in the Boltzmann equation as an external force, and the equations were rewritten under new conditions.

To the best of the authors’ knowledge, the current study is the first attempt to investigate mixed-convection heat transfer in an inclined microchannel in a slip flow regime.

The paper aims to focus on modeling of combined mixed convection and volumetric radiation within a vertical channel using a hybrid thermal lattice Boltzmann method (LBM). The multiple relaxation time LBM (MRT-LBM) is used to compute the dynamical field. The thermal field is determined by a finite difference method (FDM), and the simple relaxation time-LBM (SRT-LBM) serves to calculate the radiative part. The geometry considered concerns a vertical channel defined by two diffuse and isothermal walls. The active fluid represents a gray gas participating in absorption, emission and isotropically scattering. The parametrical study conducted aims to highlight the effect of Richardson number (Ri), Planck number (Pl) and the optical thickness (τ) on dynamical and thermal fields. It is found that radiation affects greatly heat transfer.

MRT-LBM is used to compute the dynamical field. The thermal field is determined by FDM, and SRT-LBM serves to calculate the radiative part.

This study has shown the strong capability of this approach to simulate similar problems. The Planck number largely affects the streamlines and isotherms distribution. Also, it causes disappearance of reversal flow, undesirable in most industrial applications, for low Planck numbers. The optical thickness causes the disappearance of reversal flow, in the case in which it appears, for lower opacity. However, for higher opacity it leads to a recurrence of reversed flow.

The use of a new original method composed of MRT-LBM to solve the fluid velocity, FDM to handle the temperature equation and extended SRT-LBM to compute the radiative part of the energy equation.

The purpose of this paper is to present the benefits offered by rapid prototyping (RP) models for wind‐tunnel testing as part of fourth‐year aerospace engineering student projects. Ways of overcoming some of the difficulties associated with the 3D printing technology are also discussed.

Polymer‐based RP was used to fabricate two‐aircraft models, which included stiffening metallic inserts. Testing in a subsonic‐wind tunnel was carried out and the results compared to analytic performance predictions.

Low‐cost rapid prototypes of wind‐tunnel models yielded satisfactory aerodynamic performance. The savings in acquisition cost and time allowed incorporating actual testing in the aircraft design process within the framework of a tight academic budget and schedule.

Conducting real‐wind‐tunnel testing contributes significantly to the educational experience of students; however, it had rarely been carried out when metal model fabrication was the only option. In contrast, RP facilitates an enhanced and more realistic learning experience by offering a quick and affordable means of model manufacturing.

Simple methods of reinforcing polymer‐based models were incorporated, thus presenting an inexpensive way to test and evaluate preliminary aircraft designs, in both academia and industry.

The purpose of this paper is to propose a new approach of using additively manufactured parametric models in the wind tunnel test-based aerodynamic shape optimization (ASO) framework and to present its applicability test results obtained from a realistic aircraft design problem.

For aircraft shape optimization, the following three methodologies were used. First, as a validation study, the possibility of using rapid prototyping (RP) model in the wind tunnel test was verified. Second, through the wind tunnel test-based ASO, the application and feasibility of the real fighter aircraft shape optimization were verified. A generic fighter configuration is parameterized to generate various test models using additive manufacturing. Wind tunnel tests are conducted to measure their stability criteria in high angle of attack (AOA). Finally, a computational fluid dynamics (CFD) study was performed and analysis procedures, costs and results compared to the wind tunnel test were compared and reviewed.

RP technology can significantly reduce the time and cost of generating parametric wind tunnel models and can open up new possibilities for wind tunnel tests to be used in the rigorous aerodynamic design loop. There was a slight difference between the results of the RP model and the metallic model because of rigidity and surface roughness. However, the tendency of the aerodynamic characteristics was very similarly predictable. Although there are limitations to obtaining precise aerodynamic data, it is a suitable method to be applied to comparative studies on various shapes with large geo-metric changes in the early phase of design. The CFD analysis indicates that the wind tunnel-based ASO using the RP model shows the efficiency corresponding to the CFD shape optimization.

The RP parametric models may have various assembly error sources and rigidity problems. The proposed methodology may not be suitable for collecting the accurate aerodynamic database of a final design; rather, the methodology is more suitable to screen out many configurations having fairly large shape variation in the early stage of the design process.

The wind tunnel test-based ASO can replace or supplement CFD-based ASO. In areas where CFD accuracy is low, such as high AOA flight characteristics, RP model wind tunnel-based ASO can be a research method that can secure both efficiency and accuracy advantages, providing ten times more effective in terms of cost and time. The wind tunnel test is used to obtain aerodynamic data at the final stage of shape design. It can be extended to a comparative study of several shapes in the early design phase. This procedure can be applied for both industrial level and educational aircraft design activities.

This study is the application to be applied as a parametric study on the whole aircraft, rather than using the RP model applying a simple partial control surface or configuration change of a part of the wing. The possibility of using the RP model was confirmed by comparing and verifying each other in a medium-sized wind tunnel using a relatively large RP model and a metallic model. It was verified that it can be applied in the shape design process, not the shape verification in the traditional design procedure, and a comparison with the CFD method was also performed. With further development and validation efforts, the new design framework may become an industrial standard for future aircraft development.

Based on the numerical research on the relationship between the flow pattern transition and the condensation heat transfer in circular microchannels, the purpose of this paper is to bring forward a concept of external separation circular microchannel to regulate and control the flow pattern for enhancing the condensation heat transfer.

The numerical research is based on the volume of fluid method and the vapor-liquid phase change model proposed by the present authors.

By numerical research on the condensation process of water in a general circular microchannel, it is discovered that, with the increase of the inlet velocity and the reduction of the temperature difference between the saturation temperature and the channel wall temperature, the bubble detachment frequency is raised and the water vapor condensation length is extended, representing an exponential growth. Therefore, for the condensation process with low temperature difference and high mass flow rate, it is in urgent need to regulate and control the flow pattern.

To prevent the flow pattern in the general circular microchannel converted from annular flow to slug flow and then to bubble flow, this paper brings forward a concept of external separation circular microchannel, which regulates and controls the flow pattern by discharging partial liquid from the annular wall opening. After regulation and control, the flow pattern is converted from original periodic annular flow/slug flow/bubble flow to current stable annular flow. Accordingly, the heat transfer performance is enhanced and the condensation length is lowered remarkably.

The purpose of this paper is to review the various pre-processing and post-processing approaches used to ameliorate the surface characteristics of fused deposition modelling (FDM)-based acrylonitrile butadiene styrene (ABS) prototypes. FDM being simple and versatile additive manufacturing technique has a calibre to comply with present need of tailor-made and cost-effective products with low cycle time. But the poor surface finish and dimensional accuracy are the primary hurdles ahead the implementation of FDM for rapid casting and tooling applications.

The consequences and scope of FDM pre-processing and post-processing parameters have been studied independently. The comprehensive study includes dominance, limitations, validity and reach of various techniques embraced to improve surface characteristics of ABS parts. The replicas of hip implant are fabricated by maintaining the optimum pre-processing parameters as reviewed, and a case study has been executed to evaluate the capability of vapour smoothing process to enhance surface finish.

The pre-processing techniques are quite deficient when different geometries are required to be manufactured within limited time and required range of surface finish and accuracy. The post-processing techniques of surface finishing, being effective disturbs the dimensional stability and mechanical strength of parts thus incapacitates them for specific applications. The major challenge for FDM is the development of precise, automatic and controlled mass finishing techniques with low cost and time.

The research assessed the feasibility of vapour smoothing technique for surface finishing which can make consistent castings of customized implants at low cost and shorter lead times.

The extensive research regarding surface finish and dimensional accuracy of FDM parts has been collected, and inferences made by study have been used to fabricate replicas to further examine advanced finishing technique of vapour smoothing.

The purpose of this paper is to numerically investigate the flow characteristics and extend the data of friction factor and Reynolds number product of hydrodynamically developing laminar flow in three-dimensional rectangular microchannels with different aspect ratios.

Using a finite-volume approach, the friction factor characteristics of Newtonian fluid in three-dimensional rectangular ducts with aspect ratios from 0.1 to 1 are conducted numerically under no-slip boundary conditions. A simple model that approximately predicts the apparent friction factor and Reynolds number product f_appRe is referenced as a semi-theoretical fundamental analysis for numerical simulations.

The accurate and reliable results of f_appRe are obtained, which are compared with classic numerical data and experimental data, and the simple semi-theoretical model used and all comparisons show good agreement. Among them, the maximum relative error with the classic numerical data is less than 3.9 per cent. The data of f_appRe are significantly extended to other different aspect ratios and the novel values of f_appRe are presented in the tables. The characteristics of f_appRe are analyzed as a function of a non-dimensional axial distance and the aspect ratios. A more effective and accurate fourth-order fitting equation for the Hagenbach's factor of rectangular channels is proposed.

From the reliable data, it is shown that the values of f_appRe and the model can be references of pressure drop and friction factor for developing laminar flow in rectangular channels for researchers and engineering applications.