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In order to compete with steel, a fibre-reinforced composite exhaust wall with a general-purpose resin system requires an effective but lightweight insulation layer. However a lack of experimental methods for heat transfer from turbulent gas flow to pipe walls lined with a porous insulation layer was discovered in literature. Such a test method is crucial to assess the influence of the permeability of such an insulation layer on the heat transfer rate, such that the lightest configuration can be selected. A new test method was developed and tested on samples representative for a composite exhaust. The accuracy of the method was assessed and the results for samples with different wall roughness were obtained. The behaviour of the samples under consideration proved to be more complicated than predicted by theories for impermeable pipe walls., Aerospace Structures & Materials, Aerospace Engineering

In order to compete with steel, a fibre-reinforced composite exhaust wall with a general-purpose resin system requires an effective but lightweight insulation layer. However a lack of experimental methods for heat transfer from turbulent gas flow to pipe walls lined with a porous insulation layer was discovered in literature. Such a test method is crucial to assess the influence of the permeability of such an insulation layer on the heat transfer rate, such that the lightest configuration can be selected. A new test method was developed and tested on samples representative for a composite exhaust. The accuracy of the method was assessed and the results for samples with different wall roughness were obtained. The behaviour of the samples under consideration proved to be more complicated than predicted by theories for impermeable pipe walls., Aerospace Structures & Materials, Aerospace Engineering

The purpose of this study is to simulate the two-dimensional, transient and continuous heat transfer during the thermoset Automated Tape Laying (ATL) process. The heat transfer analysis is coupled with a cure kinetics model of the thermoset prepreg tapes used for the process. Unlike most studies, the process is modelled in a Lagrangian framework and is based on the realistic boundary conditions of the ATL such as the stepwise laying down of the tapes. The model results provide information about the temperature values at any time and any location inside the thermoset composite tapes. The temperature simulation results of the model were compared with experiments. Three layers of unidirectional prepreg tapes were laid down on an aluminium mould by the TU Delft ATL machine. The experimental results were obtained from thermocouples and pyrometers placed at various locations in the lay-up and on the robotic head, respectively. The comparison between the numerical and experimental results generated three main findings. First, the pyrometer values and the thermocouple values provide insight into how important is the contact between the mould and the first layer. Secondly, the temperature fading out which was witnessed by the thermocouple measurements and could not entirely be captured by the model provided information about the influence of the heat transfer coefficients on the model predictions. Thirdly, the peak temperature magnitudes of the numerical predictions appeared to generally compare well with the experimental results. Overall, the code can be used for different parameter values such as different line speed, heated length and power of the heat source and, can predict the temperature distribution inside the composite., Aerospace Structures & Materials, Aerospace Engineering

This paper outlines the structural performance of a conformable pressurizable tank consisting of intersecting spherical shells (multi-cell tank). Multi-cell tanks outrival conventional multiple cylindrical tanks in volumetric efficiency when required to fit in a rectangular envelope in the automotive industry. When pressurized, the multi-cell (or multi-bubble) tank experiences high stress concentrations at the vicinity of the junctions, and thus the concept of effectively reinforcing those regions without adding significant excess weight becomes crucial. Furthermore when applied for cryogenic medium storage the heat transfer between different bodies and generation of respective thermal stresses in such vessels makes the solution more complicated. In this paper the effect of the i) fiber-reinforced materials at the membrane and ii) unidimensional carbon tows at the intersections on the structural integrity of the tank is analyzed for different loading scenarios., Aerospace Structures & Materials, Aerospace Engineering

The purpose of this study is to simulate the two-dimensional, transient and continuous heat transfer during the thermoset Automated Tape Laying (ATL) process. The heat transfer analysis is coupled with a cure kinetics model of the thermoset prepreg tapes used for the process. Unlike most studies, the process is modelled in a Lagrangian framework and is based on the realistic boundary conditions of the ATL such as the stepwise laying down of the tapes. The model results provide information about the temperature values at any time and any location inside the thermoset composite tapes. The temperature simulation results of the model were compared with experiments. Three layers of unidirectional prepreg tapes were laid down on an aluminium mould by the TU Delft ATL machine. The experimental results were obtained from thermocouples and pyrometers placed at various locations in the lay-up and on the robotic head, respectively. The comparison between the numerical and experimental results generated three main findings. First, the pyrometer values and the thermocouple values provide insight into how important is the contact between the mould and the first layer. Secondly, the temperature fading out which was witnessed by the thermocouple measurements and could not entirely be captured by the model provided information about the influence of the heat transfer coefficients on the model predictions. Thirdly, the peak temperature magnitudes of the numerical predictions appeared to generally compare well with the experimental results. Overall, the code can be used for different parameter values such as different line speed, heated length and power of the heat source and, can predict the temperature distribution inside the composite., Aerospace Structures & Materials, Aerospace Engineering

In order to compete with steel, a fibre-reinforced composite exhaust wall with a general-purpose resin system requires an effective but lightweight insulation layer. However a lack of experimental methods for heat transfer from turbulent gas flow to pipe walls lined with a porous insulation layer was discovered in literature. Such a test method is crucial to assess the influence of the permeability of such an insulation layer on the heat transfer rate, such that the lightest configuration can be selected. A new test method was developed and tested on samples representative for a composite exhaust. The accuracy of the method was assessed and the results for samples with different wall roughness were obtained. The behaviour of the samples under consideration proved to be more complicated than predicted by theories for impermeable pipe walls., Aerospace Structures & Materials, Aerospace Engineering

This paper outlines the structural performance of a conformable pressurizable tank consisting of intersecting spherical shells (multi-cell tank). Multi-cell tanks outrival conventional multiple cylindrical tanks in volumetric efficiency when required to fit in a rectangular envelope in the automotive industry. When pressurized, the multi-cell (or multi-bubble) tank experiences high stress concentrations at the vicinity of the junctions, and thus the concept of effectively reinforcing those regions without adding significant excess weight becomes crucial. Furthermore when applied for cryogenic medium storage the heat transfer between different bodies and generation of respective thermal stresses in such vessels makes the solution more complicated. In this paper the effect of the i) fiber-reinforced materials at the membrane and ii) unidimensional carbon tows at the intersections on the structural integrity of the tank is analyzed for different loading scenarios., Aerospace Structures & Materials, Aerospace Engineering