This thesis focuses on CFD analysis of the Aircar 5.0 flying car prototype. The theoretical part covers basic information about the connection between the aerodynamics of airplanes and cars as well as cars themselves. The computational part begins with the calibration of the mathematical model, continues with the CFD simulations, which have the role to determine basic aerodynamic characteristics of the Aircar in vehicle mode. There are several configurations tested to find out their influence on aerodynamic stability and their advantages and disadvantages are summed up in the conclusion chapter.

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Abstract <br /> This thesis deals with the numerical investigation of the upper section of a building-integrated photovoltaic/thermal double-fa??ade. The upper section consists of an airflow window with a between-the-panes roller blind. The purpose of this thesis is to develop and validate a numerical model in order to optimize the design of the system. The lower section, which consists of building-integrated photovoltaics, has already been modelled at Concordia University. The results from the lower section will be used as inputs to the upper section. <br /><br /> The validation of the model was carried out in three stages. In the first stage, the model was validated for forced convection between parallel plates using analytical data as benchmarks. In the second stage, a radiation analysis was performed for single, double and triple-glazed closed system with natural convection only. In the third and final validation stage, experimental data gathered from the Solar Lab at Concordia University was compared to the numerical model. The model included the effects of radiation for an open system with forced convection and a between-the-panes roller blind. For all three stages of validation, the results from the model were in excellent agreement with the benchmarking data. <br /><br /> Once the model was validated, a parametric analysis was used to determine the effects of varying key model parameters. The outlet temperature, the useful energy gain, and the net energy gain of the system were plotted as a function of inlet velocity. It was concluded that as the flow rate through the cavity was increased, the air temperature at the outlet approached that of the outdoor ambient air. By computing the heat generated from advection as well as the total losses from the system, including the heat lost from the indoor environment as well as the power consumed by the fan, the net useful heat gain of the system was calculated as a function of insolation level. Operating points (of the fan) for the upper section were therefore determined as functions of insolation level. A second order polynomial equation provided an excellent fit to the data and could therefore be used to determine the ideal operating point of the upper section for any insolation level.

No description available.

Abstract <br /> This thesis deals with the numerical investigation of the upper section of a building-integrated photovoltaic/thermal double-façade. The upper section consists of an airflow window with a between-the-panes roller blind. The purpose of this thesis is to develop and validate a numerical model in order to optimize the design of the system. The lower section, which consists of building-integrated photovoltaics, has already been modelled at Concordia University. The results from the lower section will be used as inputs to the upper section. <br /><br /> The validation of the model was carried out in three stages. In the first stage, the model was validated for forced convection between parallel plates using analytical data as benchmarks. In the second stage, a radiation analysis was performed for single, double and triple-glazed closed system with natural convection only. In the third and final validation stage, experimental data gathered from the Solar Lab at Concordia University was compared to the numerical model. The model included the effects of radiation for an open system with forced convection and a between-the-panes roller blind. For all three stages of validation, the results from the model were in excellent agreement with the benchmarking data. <br /><br /> Once the model was validated, a parametric analysis was used to determine the effects of varying key model parameters. The outlet temperature, the useful energy gain, and the net energy gain of the system were plotted as a function of inlet velocity. It was concluded that as the flow rate through the cavity was increased, the air temperature at the outlet approached that of the outdoor ambient air. By computing the heat generated from advection as well as the total losses from the system, including the heat lost from the indoor environment as well as the power consumed by the fan, the net useful heat gain of the system was calculated as a function of insolation level. Operating points (of the fan) for the upper section were therefore determined as functions of insolation level. A second order polynomial equation provided an excellent fit to the data and could therefore be used to determine the ideal operating point of the upper section for any insolation level.

No description available.

M.Ing. / The characterisation of the flow field and thermal performance of supply air windows (airflow windows operating in supply mode) have been a topic of interest for at least two decades. Computational Fluid Dynamics (CFD) as well as other simulation methods have been used to model and characterise the flow field, temperature distributions and thermal performance of the supply air window in recent years. Where experimental validation of the velocity (only outlet velocity) and temperature predictions has been provided the error between experiment and CFD (and other forms of simulation) is in the order of 50 % and 3 ◦C (10-13 %), respectively. Furthermore, a large part of the literature does not have experimental validation of the simulation results. The significant error in many of the studies, that provide experimental val- idation of the velocity field, is attributed to inappropriate turbulence mod- els, unrealistic boundary conditions, neglecting significant three-dimensional effects, solar radiation effects not entirely accounted for, mesh sensitivity studies neglected and material properties of glass and air assumed constant. The aim of this research was to characterise a supply air window in terms of its velocity field, temperature distributions and thermal performance. This was done by mathematically modelling the fluid dynamics and heat trans- fer processes in a supply air window and solving the model in a commer- cial CFD code, namely ANSYS Fluent 12.1. Furthermore, an experimental rig was designed, constructed and used to measure the flow field and tem- peratures with the aim of validating the CFD models. The CFD models incorporated appropriate turbulence models, realistic boundary conditions, three-dimensional effects, solar radiation, temperature dependent material properties and a mesh sensitivity study. The CFD models and experiments were setup for forced and natural flow conditions. Laser Doppler Velocimetry has not been used for velocity field measure- ments in an airflow window to date. The experimental setup made use of Laser Doppler Velocimetry to measure the velocity field and turbulence in- tensities. The Laser Doppler Velocimeter (LDV) probe was positioned using a three axis computer controlled traversing mechanism. Furthermore, flow visualisation experiments were done to qualitatively capture the flow field. The results from the CFD are partially in good agreement with the exper- imental work. Qualitatively the flow field as predicted by CFD is in good agreement with the results from the flow visualisation experiments. Quan- titatively the results from the CFD are in good agreement with the tem- perature measurements, however, there is noticeable error between the LDV readings and the velocities as well as turbulence intensity values predicted by CFD. The error, with regards to velocity and turbulence intensity, may be attributed to the experimental error caused by problems with flow seeding as well as the isotropic turbulence assumption inherent in the turbulence model (SST k − ω) used.

No description available.

Infants and young children with tracheostomies need better respiratory monitors. Mucus in the tracheostomy tube presents a serious choking hazard.  Current devices indirectly detect respiration, often yielding false or delayed alarms.  A compact ultrasonic time-of-flight (TOF) airflow sensor capable of attaching directly to the tracheostomy tube has been developed to address this need.  The ultrasonic flow sensing principle, also known as transit time ultrasound, is a robust method that correlates the timing of acoustic signals to velocity measurement.  The compact prototype developed here can non-invasively measure all airflow into and out of a patient, so that breath interruption can easily be detected. This paper concerns technical design of the sensor, including the transducers, analog/digital electronics, and embedded systems hardware/software integration.   Inside the sensor's flow chamber, two piezoelectric transducers sequentially transmit and receive ping-like acoustic pulses propagating upstream and downstream of flow.  A microcontroller orchestrates measurement cycles, which consist of the transmission, reception, and signal processing of each acoustic pulse.  The velocity and direction of airflow influence transit time of the acoustic signals.  Combining TOF measurements with the known geometry of the flow chamber, average air velocity and volumetric flow rate can be calculated.  These principles have all been demonstrated successfully by the prototype sensor developed in this research. / Master of Science

Nasal high flow (NHF) cannulae are used to deliver heated and humidified air to patients at steady flows ranging from 5-50 l/min. Knowledge of the airflow characteristics within the nasal cavity with NHF and during natural breathing is essential to understand the treatment's efficacy. In this thesis, the distribution and velocity of the airflow in the human nasal cavity have been mapped during natural and NHF assisted breathing with planar- and stereo-PIV in both steady and oscillatory flow conditions. Anatomically accurate transparent silicone models of the human nasal cavity were constructed using CT scan data and rapid prototyping. Breathing flowrates and waveforms were measured in vivo and dimensionally scaled by Reynolds and Womersley number matching to reproduce physiological conditions in vitro. Velocities of 2.8 and 3.8 m/s occurred in the nasal valve during natural breathing at peak expiration and inspiration, respectively; however on expiration the maximum velocity of 4.2 m/s occurred in the nasopharynx. Velocity magnitudes differed appreciably between the left and right sides of the nasal cavity, which were asymmetric. NHF modifies nasal cavity flow patterns significantly, altering the proportion of inspiration and expiration through each passageway and producing jets with in vivo velocities up to 20.8 m/s for 40 l/min cannula flow. The main flow stream passed through the middle airway and along the septal wall during both natural inspiration and expiration, whereas NHF inspired and expired flows remained high through the nasal cavity. Strong recirculating features are created above and below the cannula jet. Results are presented that suggest the quasi-steady flow assumption is invalid in the nasal cavity during both natural and NHF assisted breathing. The importance of using a three-component measurement technique when investigating nasal flows has been highlighted. Cannula flow has been found to continuously flush the nasopharyngeal dead space, which may enhance carbon dioxide removal and increase oxygen fraction. Close agreement was found between numerical and experimental results performed in identical conditions and geometries.