Cold aisles containments are used in data centers buildings t o improve the thermal managements of the ITservers. In the pr esent study, an experimental investigation of air flow and thermal management of datacenter buildings is conducted for different arrangements of cold aisles containments. A scaled ph ysical modelsimulating real data centers is designed using scale modeling theory and constructed for the sake of thepresent experimental work. The data center scaled model accommodate a row of three racks; each rackincluded four servers for testing purposes. Thr ee arrang ements of cold ai sles are t ested: (i) fr ee open cold aisle,(ii) semi-enclosed cold aisles where the aisles are enclosed from the sides, and (iii) full enclosed cold aisles,where the aisles are enclosed from sides and top. F ro nt and rear racks temperatur es profile, servers tem-peratures and performance measuring paramet ers Supply/Return Heat Index (SHI/RHI) are used to evaluatethe thermal management/performance of the data centers racks. Experiments w ere conducted at differentracks power densities. The results showed that (i) increasing data centers power density and supplied air flowrates improves SHI but increases servers temperature, (ii) using semi-enclosed cold aisles relatively improvethe thermal performance of the data centers, (iii) using full enclosed cold aisles dramatically improv e thethermal performance of the data center servers, and (vi) the percentage of enhancement in data centersperformance due to using cold aisle containments dramatically increases with increasing the power