1,721,240 research outputs found
Experimental heat transfer studies with infrared camera
No full textThe master thesis described on this report consists on two experimental heat transfer studies using infrared thermography technology.
The fi rst part, the temperature evolution of two cooled surfaces is studied.
Representing the thermal e ect su ered by the pistons during the process of injection in diesel engines. The results are compared with CFD simulations and with thermocouple measuremnts that were done previously. This study is useful to understand better the reasons why pistons are damage and to
constrast the di erent methods.
In the second part, the convection heat transfer coe cient inside a linear
cascade is studied. This coe cient is measured on a instrumented end-wall,
showing the thermal behavior between the vanes and wall interaction. Measuring
convection heat transfer coe cient on the endwalls can provide a better
understanding of the heat transfer mechanisms in OGVs section. This
enables the posibility of optimizing the coolant needed in this section and the
material taht can be used for manufacturing OGVs, i.e; composite material are lighter than metal but they have lower melting temperature. Moreover, as in the other experiment the data can be compared with other methods and contrasted with CFD simulations.
Furthermore, another goal of the experiment is to validate this methodology and technique to get this data.Outgoin
Experimental heat transfer studies with infrared camera
No full textThe master thesis described on this report consists on two experimental heat transfer studies using infrared thermography technology.
The fi rst part, the temperature evolution of two cooled surfaces is studied.
Representing the thermal e ect su ered by the pistons during the process of injection in diesel engines. The results are compared with CFD simulations and with thermocouple measuremnts that were done previously. This study is useful to understand better the reasons why pistons are damage and to
constrast the di erent methods.
In the second part, the convection heat transfer coe cient inside a linear
cascade is studied. This coe cient is measured on a instrumented end-wall,
showing the thermal behavior between the vanes and wall interaction. Measuring
convection heat transfer coe cient on the endwalls can provide a better
understanding of the heat transfer mechanisms in OGVs section. This
enables the posibility of optimizing the coolant needed in this section and the
material taht can be used for manufacturing OGVs, i.e; composite material are lighter than metal but they have lower melting temperature. Moreover, as in the other experiment the data can be compared with other methods and contrasted with CFD simulations.
Furthermore, another goal of the experiment is to validate this methodology and technique to get this data.Outgoin
Experimental heat transfer studies with infrared camera
No full textThe master thesis described on this report consists on two experimental heat transfer studies using infrared thermography technology.
The fi rst part, the temperature evolution of two cooled surfaces is studied.
Representing the thermal e ect su ered by the pistons during the process of injection in diesel engines. The results are compared with CFD simulations and with thermocouple measuremnts that were done previously. This study is useful to understand better the reasons why pistons are damage and to
constrast the di erent methods.
In the second part, the convection heat transfer coe cient inside a linear
cascade is studied. This coe cient is measured on a instrumented end-wall,
showing the thermal behavior between the vanes and wall interaction. Measuring
convection heat transfer coe cient on the endwalls can provide a better
understanding of the heat transfer mechanisms in OGVs section. This
enables the posibility of optimizing the coolant needed in this section and the
material taht can be used for manufacturing OGVs, i.e; composite material are lighter than metal but they have lower melting temperature. Moreover, as in the other experiment the data can be compared with other methods and contrasted with CFD simulations.
Furthermore, another goal of the experiment is to validate this methodology and technique to get this data.Outgoin
Turbulent boundary layer: comparison between a flat plate and a rotating disk with and without periodic roughness
No full textIn order to understand and predict the behavior of a flow around an object it is necessary to study the phenomenon present on the close-to-the-wall region of the flow, where the viscous forces cannot be neglected nor the variations of the properties of the flow. This region is called the boundary layer. In many situations, the contribution of the viscous friction in the boundary layer into the total drag can be substantial, and understanding of the effect of the roughness on the boundary layer is of importance. This project is focused on the study of the boundary layer created near two different objects: a flat plate and a rotating disk.
The flat plate is widely used in fundamental studies and in the engineering industry as an approximation of more complex models, for instance the ship hull in the naval engineering. The influence of the roughness on the friction drag can be obtained from testing of different plate models in a towing tank. Although this approximation usually offers a good agreement, experimental data and measurements are expensive to obtain. In order to reduce the cost of the experiments, a rotating disk is used an approximation of a flat plate since the installation and design of the experiment is not only cheaper but also simpler. The validation of this approximation is the main objective of this project and it is carried out by a study which is focused on finding similarities between both boundary layer properties with the aid of Computational Fluid Dynamics (CFD). Also, experimental measurements are compared with CFD result with the aim of a validation of the CFD results.Outgoin
Turbulent boundary layer: comparison between a flat plate and a rotating disk with and without periodic roughness
Full text linkIn order to understand and predict the behavior of a flow around an object it is necessary to study the phenomenon present on the close-to-the-wall region of the flow, where the viscous forces cannot be neglected nor the variations of the properties of the flow. This region is called the boundary layer. In many situations, the contribution of the viscous friction in the boundary layer into the total drag can be substantial, and understanding of the effect of the roughness on the boundary layer is of importance. This project is focused on the study of the boundary layer created near two different objects: a flat plate and a rotating disk.
The flat plate is widely used in fundamental studies and in the engineering industry as an approximation of more complex models, for instance the ship hull in the naval engineering. The influence of the roughness on the friction drag can be obtained from testing of different plate models in a towing tank. Although this approximation usually offers a good agreement, experimental data and measurements are expensive to obtain. In order to reduce the cost of the experiments, a rotating disk is used an approximation of a flat plate since the installation and design of the experiment is not only cheaper but also simpler. The validation of this approximation is the main objective of this project and it is carried out by a study which is focused on finding similarities between both boundary layer properties with the aid of Computational Fluid Dynamics (CFD). Also, experimental measurements are compared with CFD result with the aim of a validation of the CFD results.Outgoin
Turbulent boundary layer: comparison between a flat plate and a rotating disk with and without periodic roughness
No full textIn order to understand and predict the behavior of a flow around an object it is necessary to study the phenomenon present on the close-to-the-wall region of the flow, where the viscous forces cannot be neglected nor the variations of the properties of the flow. This region is called the boundary layer. In many situations, the contribution of the viscous friction in the boundary layer into the total drag can be substantial, and understanding of the effect of the roughness on the boundary layer is of importance. This project is focused on the study of the boundary layer created near two different objects: a flat plate and a rotating disk.
The flat plate is widely used in fundamental studies and in the engineering industry as an approximation of more complex models, for instance the ship hull in the naval engineering. The influence of the roughness on the friction drag can be obtained from testing of different plate models in a towing tank. Although this approximation usually offers a good agreement, experimental data and measurements are expensive to obtain. In order to reduce the cost of the experiments, a rotating disk is used an approximation of a flat plate since the installation and design of the experiment is not only cheaper but also simpler. The validation of this approximation is the main objective of this project and it is carried out by a study which is focused on finding similarities between both boundary layer properties with the aid of Computational Fluid Dynamics (CFD). Also, experimental measurements are compared with CFD result with the aim of a validation of the CFD results.Outgoin
PIV measurements of Turbine Rear Structure flow
No full textThe flow field characteristics of a TRS (turbine rear structure) have been experimentally
investigated using the non-intrusive PIV (particle image velocimetry)
technique. The TRS is the structure located downstream of the LPT (low-pressure
turbine) in a jet engine. The flow features through this structure are extremely
complex since non-uniformities generated at the LPT interact with the OGVs (outlet
guide vanes) located inside this structure.
The experiments were conducted at the Chalmers Fluid Mechanics department
wind tunnel, which consists in a closed loop facility where an LPT is located upstream
of the test section to provide engine-realistic inlet boundary conditions to
the TRS.
In particular, the measurements involved the three following regions of the flow:
the outlet of the TRS (2D and stereo PIV), Plane B (stereo PIV) and the boundary
layer around the single OGV of the TRS (2D PIV).
Moreover, the experiments were conducted varying the value of two coefficients.
The first one is the Reynolds number based on the channel height. Two values
were tested corresponding to the low and high speed respectively: Re = 235000
and Re = 465000.
The second one is the flow coefficient that is defined as the ratio between the axial
velocity of the flow and the rotational speed of the turbine. Four different values
of this coefficient were tested in the whole experimental campaign: 0.588, 0.622,
0.657 and 0.775.
Several quantities of interest were calculated from the data recorded through the
software Dynamic Studio 2016-a, such as the instantaneous velocity and vorticity
fields but also the main statistics (mean velocity field, standard deviations of velocity
components etc.).
Afterwards, a POD (Proper Orthogonal Decomposition) analysis was applied to
the data to investigate the presence of relevant modes.
Finally, an FFT transform analysis was conducted to make a comparison with the
POD results.
To conclude, the quality of the results can be deemed satisfactory, considering
that new measurements will be taken in the near future. However, the presence
of technical issues such as multiple reflections coming from the internal structure
of the TRS or low images recording sampling frequency led to an only partial
comprehension of the complex phenomena happening inside the TRS
Prediction of Laminar-Turbulent Transition on an Airfoil at High Level of Free-Stream Turbulence
No full textPrediction of laminar-turbulent transition at high level of free-stream turbulence in boundary layers of airfoil geometries with external pressure gradient changeover is in focus. The aim is a validation of a transition model for transition prediction in turbomachinery applications. Numerical simulations have been performed by using a transition model by Langtry and Menter for a number of different cases of pressure gradient, at Reynolds number-range, based on the airfoil chord, 50 000 ≤ Re ≤ 500 000 and free-stream turbulence intensities 2 % and 4 %. The validation of the computational results against the experimental data showed good performance of used turbulence model for all test cases
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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