The overall objective of the present work is to evaluate the performance of three turbulence models, with a view to predicting characteristics of airflow within an anisothermic cavity. The standard K-c. model, the Renormalisation Group model (RNG) and the Reynolds stress model (RSM) are used in conjunction with the Fluent code. The accuracy and the relative performance of the three models are evaluated by comparing their numerical results with experimentally obtained data. This comparison is made for the constant flow rate of a twodimensional turbulent mixed convective airflow.
The present paper deals with one of the most important mechanisms of inter-zone mass and energy transfer, namely the buoyancy-driven flows through stairwells that connect the floors of buildings. To further investigate these phenomena, experimental as well as theoretical studies have been carried out. A series of experiments have been performed in order to study the airflow through a typical stairwell that connects the two individual zones of a two-storey house. Airflow rates between the two zones were measured using a single tracer gas decay technique.
The keeping of animals in livestock buildings requires the ventilation of these buildings. Good climate conditions for the animals have to be guaranteed as well as little emissions and immissions from the livestock buildings. An important role for both of these opposite requirements plays the airstream inside and outside of the building. For this reason wind tunnel modelling and digital imaging by using a laser light sheet is applied beside other methods at the Institute of Agricultural Engineering Bornim.
We present a series of analogue laboratory experiments of the transient exchange flow between a room filled with warm air and a cold exterior following the opening of a doorway. Our experiments suggest that the time-scale for mixing the fluid in the room below the top of the doorway is independent of the door height. We then describe the steady-state two-layer stratification that is established when, in addition to the exchange flow, a localised heat source provides heat at the base of the room.
As the thermal sensation of humans depends directly on heat transfer characteristics between the body surface and the surrounding environment, it is very important to clarify the heat transfer characteristics of a human body surface in detail. This paper describes a combined numerical (NOTE I) simulation system of airflow, thermal radiation and moisture transport based on a human thermo-physiological model used to examine the total (sensible + latent) heat transfer characteristics of a body surface. The human body is assumed to be naked (NOTE 2).
This paper discusses the experimental study of direct delivery of cold air into a full scale environmental chamber using different diffusers, i.e. a multi-cone circular ceiling diffuser, a vortex diffuser and a nozzle type diffuser. Comparisons have been made of the following: mean flow patterns, temperature distribution and condensation risk. The vortex diffuser exhibits a higher induction effect than that of the nozzle type diffuser. However, the air speed generated by the vortex diffuser is generally lower than that of nozzle type diffuser.
A study of the reliability of systems by considering the ability of different systems to maintain a required air flow rate over time is included in a subtask of IEA Annex 27 'Evaluation and Demonstration of Domestic Ventilation Systems'. Measurements and calculations were performed to determine the variation in ventilation rates due to variation in climate and variation in performance of the ventilation system. Dwellings with passive stack, mechanical exhaust and mechanical exhaust-supply ventilation, representative of the Swedish housing stock, were studied.
This paper describes a methodology based on computational and analytical modelling techniques in the prediction of building internal pressure gain functions. It first involves computational modelling of the transient response following a sudden opening, which predicts both the Helmholtz frequency and the damping characteristics fairly accurately. The parameter derived by fitting the analytical model to the computed response are then used in the prediction of the gain function.
This paper presents a set of detailed experimental data of room airflow with displacement ventilation. These data were obtained from a new environmental test facility. The measurements were conducted for three typical room configurations: a small office, a large office with partitions, and a classroom. The distributions of air velocity, air velocity fluctuation, and air temperature were measured by omnidirectional hotsphere anemometers, and contaminant concentrations were measured by tracer gas at 54 points in the rooms. Smoke was used to observe airflow.