PIV measurement of human thermal convection flow in a simplified vehicle cabin (original) (raw)
Related papers
Experimental parametric study of forced and mixed convection in a passenger aircraft cabin mock-up
Building and Environment, 2009
Forced and mixed convection has been investigated experimentally in a full scale passenger aircraft cabin mock-up. The mock-up represents a generic cabin section of the A380 upper deck. Large scale particle image velocimetry (PIV) and temperature field measurements were conducted in a cross sectional plane of the cabin mock-up. The flow fields for two different air inlet configurations were measured and analysed under isothermal and cooling conditions. Furthermore the flow rates at the different air inlet positions were varied while keeping the air exchange rate constant. Our extensive experimental parametric study demonstrates that the flow field in aircraft cabins is affected by various fluid mechanical phenomena. Interaction between the supplied air jets, negative buoyancy forces acting on these air jets and interaction of thermal plumes with the supplied air jets, all influence the flow field inside the cabin. The impact of these effects differs considerably depending on the ventilation configuration and relative mass flow settings at the supply inlets.
Human convective boundary layer and its interaction with room ventilation flow
Indoor Air, 2014
This study investigates the interaction between the human convective boundary layer (CBL) and uniform airflow with different velocity and from different directions. Human body is resembled by a thermal manikin with complex body shape and surface temperature distribution as the skin temperature of an average person. Particle image velocimetry (PIV) and pseudocolor visualization (PCV) are applied to identify the flow around the manikin's body. The findings show that the direction and magnitude of the surrounding airflows considerably influence the airflow distribution around the human body. Downward flow with velocity of 0.175 m/s does not influence the convective flow in the breathing zone, while flow at 0.30 m/s collides with the CBL at the nose level reducing the peak velocity from 0.185 to 0.10 m/s. Transverse horizontal flow disturbs the CBL at the breathing zone even at 0.175 m/s. A sitting manikin exposed to airflow from below with velocity of 0.30 and 0.425 m/s assisting the CBL reduces the peak velocity in the breathing zone and changes the flow pattern around the body, compared to the assisting flow of 0.175 m/s or quiescent conditions. In this case, the airflow interaction is strongly affected by the presence of the chair.
Building and Environment, 2008
Ventilation effectiveness in aircraft cabins is a critical factor for minimizing the cross-contamination of airborne pathogens exhaled by the passengers. In this study, a full-scale section of a Boeing 767 aircraft cabin containing thirty five mannequins was used for evaluating the ventilation effectiveness and characterizing the air distribution. Each mannequin was attached with a body heater and an outlet of carbon dioxide to simulate breathing. A set of experiment trials was conducted to measure the local mean age of air and the ventilation effectiveness factor (VEF) at the breathing level of the passengers. Carbon dioxide was used as the trace gas to determine the local mean age of air and the VEF. The air velocity profiles measured using a volumetric particle tracking velocimetry (VPTV) system was used to generate the airflow patterns and investigate the underlying mechanism affecting the local mean age of air and the VEF. In addition, measurements were conducted at different air supply rates to examine its effect on the ventilation performance.
Experimental and numerical simulations of turbulent ventilation in aircraft cabins
Energy, 2006
Airflow in a generic airplane cabin has been investigated numerically by means of Reynolds averaged Navier-Stokes computations and experimentally by particle image velocimetry (PIV). High and low Reynolds number as well as two layer turbulence models were tested for their ability to describe turbulent velocity fields. Special attention was given to the flow of the incoming air jet along the luggage compartment. Comparison with PIV measurements reveals that for reliable prediction of isothermal cabin flow, low Reynolds number turbulence models have to be used.
Analysis of thermal plumes generated by a seated person, a thermal manikin and a dummy
In this work, the main features of the mean velocity and temperature fields developed above different kinds of stationary heat sources, in quiet and isothermal surroundings, are presented and discussed. The major objective of the present contribution concerns the analysis of the modeling capabilities of thermal manikins and heated dummies, as compared to the case of real occupants, engaged on sedentary activities, typical of office work. As it might be expected, the buoyancy driven flow promoted by a thermal manikin (nude or dressed) provides a more sound reproduction of what may be generated by a human being, here restricted to the case of a seated person, normally dressed with common winter clothing. Consideration of the axial decay of mean velocities and temperatures clearly suggest that the development of an axisymmetric turbulent plume originating at a point source is not fully attained. Instead, the flow field seems to be better described by a shear free heated wake, a situation that calls for further analysis.
Human thermal comfort in aircraft cabins
Providing thermal comfort and good air quality are important factors to create a healthy and comfortable environment for passengers in airplane. The current ventilation system is the mixed one, 50% of air is fresh air from outside and the other 50% is recirculated air from the cabin. Personalized systems are introduced to improve those two factors. In this research the air distribution system is a combined system between the mixed ventilation system and the gaspers, the effect of the gaspers are investigated on the whole cabin of the economy section of BOEING 777 commercial aircraft. Temperature and velocity distributions are discussed; also PMV and PPD are used to predict the thermal sensation of passengers. It was found that the gaspers increase the air velocity in the cabin, makes the temperature distribution more uniform, and provide thermal comfort for passenger on his demand. The investigation is done by computational fluid dynamics package (ANSYS FLUENT 15.0), FLUENT is the solver, it solves the continuity, momentum, energy, and turbulence model equations. Meshes with sizes between 6,000,000 and 7,000,000 cells are generated in each case.
Thermal environment around passengers in an aircraft cabin
HVAC&R RESEARCH
This investigation explored the numerical simulation method to predict thermal environment and heat transfer of passengers in the first-class cabin of an actual MD-82 commercial airliner on the ground through comparisons of experimental measurement data and numerical simulation results. The validated computational fluid dynamics model was then used to study passenger's thermal sensation in a newly designed aircraft cabin at 39,800 ft (12,131 m) cruise height in summer conditions. The convective heat transfer coefficient, predicted mean vote, and predicted percentage dissatisfied on the human body surfaces were analyzed and quantified. Both the measured data and simulation result showed that an approximation of 74.1% of heat loss from the human body surface was caused by convection heat transfer, which means that the ratio between convection and radiation was about 7:3 under the condition of this experiment. In the newly designed aircraft, the two passengers sitting in the aisle ...
E3S Web of Conferences, 2018
Nowadays, thermal comfort became one of the criteria in choosing a vehicle. In last decades time spent by people in vehicles had risen substantially. During each trip, thermal comfort must to be ensured for a good psychological and physical state of the passengers. Also, a comfortable environment leads to a higher power concentration of the driver thereby to a safe trip for vehicle occupants and for all traffic participants. The present study numerically investigated the effect of human body sited in the driver's place, over the air velocity distribution and over the thermal comfort in a passenger compartment. CFD simulations were made with different angles of the left inlet grill, in both cases, with and without driver presence. In majority of the actual vehicles environment studies, are made without consideration of human body geometry, in this case, the results precision can be affected. The results show that the presence of human body, lead to global changing of the whole fl...
Mixed Convection in a Full Scale Aircraft Cabin Mock-Up
2006
For the study of mixed convective airflows, a full scale double aisle aircraft cabin mock-up has been built at the German Aerospace Center in Göttingen. It is designed as a testing configuration with realistic boundary conditions for commercial Computational Fluid Dynamics (CFD)-codes as well as the DLR in house code THETA. The aim is the reliable prediction of cabin air-flow by means of CFD under consideration of computational time. Special attention will be given to the proper prediction of the separation lines as well as the resulting temperature distribution, making necessary validation of the used turbulence and radiation models. In order to provide a comprehensive validation data base the flow in the mock-up was studied with Particle Image Velocimetry (PIV), infrared thermography, and field temperature measurements. The influence of buoyancy effects and the interaction of the incoming air jets on the flow field have been studied independently by switching from isothermal to cooling conditions and by a systematical variation of the relative volume flow of the air inlets.