Influence of Geometry of Thermal Manikins on Room Airflow

Abstract

A number of different thermal manikins have been applied in literature to experimentally study the indoor environment. These manikins differ in size, shape and level of geometric complexity ranging from simple box or cylinder shaped thermal manikins to humanlike breathing thermal manikins. None of the reported studies however, deals with the influence of geometry of the thermal manikin. This paper provides an experimental study on the influence of manikin geometry on the global and local airflow around a manikin located in mixing ventilated surroundings. It was found that the air velocities express little influence of manikin geometry when global flow is considered, that is flow at some distance from the manikin. However, locally the velocity levels showed to be significantly different. INDEX TERMS Mixing ventilation, thermal manikin, air movement INTRODUCTION In indoor environmental engineering and research occupants are often accounted for by person simulators. In experimental work these simulators can be categorised as either thermal manikins (heat source and obstacle) affecting the room airflow pattern and temperature distribution or so-called breathing thermal manikins that in addition can be used as a tool for assessment of thermal comfort, indoor air quality and personal exposure. A number of different thermal manikins have been applied in literature. Bjorn and Nielsen (2002), Brohus and Nielsen (1996) and Xing, Hatton and Awbi (2001) focus on thermal comfort and personal exposure, while others take a fluid dynamics point of view in the investigation of airflow and temperature distribution around the human body (Chang and Gonzalez, 1993; Myers, Hosni and Jones, 1998; Lewis et al., 1969). The manikins applied in indoor environmental research differ in size, shape and level of geometric complexity ranging from simple box or cylinder shaped thermal manikins to humanlike breathing thermal manikins. Simple manikins are often preferred as they are cheaper to buy and more easy to operate. Topp, Nielsen and Sorensen (2002) and Topp (2003) investigated the influence of geometry of computer simulated persons on local and global air distribution and convective heat transfer as well as concentration distribution and personal exposure by means of Computational Fluid Dynamics. The results showed that a simple geometry is sufficient when global flow is considered while a more detailed geometry * Contact author email: ct@civil.auc.dk should be used to assess thermal and atmospheric comfort. None of the experimental studies reported in literature however, deals with the influence of geometry of the thermal manikin. It is straightforward to believe that the more humanlike geometry provides the better results but so far there is a lack of information on how much better the results would be. This work focuses on the influence of manikin geometry on the global and local airflow around a manikin located in mixing ventilated surroundings. In another study Topp et al. (2003) studies the influence of manikin geometry on concentration distribution and personal exposure in a displacement ventilated room. METHODS A series of full-scale experiments with four different thermal manikins were performed. The geometries of the thermal manikins are highly different while height and surface area are almost identical, see Figure 1. Figure 1. The investigated thermal manikins. Both thermal manikin 1 and 2 (TM1 and TM2) is a simple rectangular shaped geometry of a seated person based on a standing Computer Simulated Person proposed by Brohus (1997). TM1 has “no legs” that is air is not allowed to pass between the legs, while TM2 has a space between the legs. TM3 and TM4 are breathing thermal manikins with a more complex and humanlike geometry. The manikins are identical with those applied in Topp et al. 2003. Figure 2. Airflow pattern in mixing ventilated surroundings (left) and the experimental set-up (right). The experimental setup is a channel-like geometry with dimensions L×H×W = 2.50 m × 2.44 m × 1.18 m. TM1 TM2 TM3 TM4