Vol. 20 No. 2 (2005)

Flow field at the inlet of a combustor under the influence of swirler vanes was investigated computationally. The isothermal flow was examined to predict the combustion stability. The simulations indicate different flow-field characteristics can be achieved under the same swirl number. In addition to swirl number, swirl velocity induces the existence of centrifugal force. This force affect velocity profile peak, static pressure profile, radially; and recirculation zone, axially.

Environmental issues enforce us to find environmental friendly alternative refrigerants. Increasing energy consumption as consequence of widespread usage of air-conditioning systems needs effort to find efficient systems. Use ability of alternative refrigerants and effect of modified vapor-compression cycles were investigated in this research. In figuring effects of their application on a real air-conditioning system, analysis of redesign of air-conditioning system was concerned to make clear the problem. The results confirm that a right selection of refrigerants to air-conditioning system…

In this research, a simulation method has been developed for designing a solar air conditioner and predicting its perfomances. This simulation based on solar irradiation data, solar collector performance data, LiBr-H2O absorption chiller single effect performance data, Phase Change Material (PCM) data as its inputs. Napthalene is used for HTTS and acetic acid is used for TTS. Energy balance, mass balance, and characteristic equations of each component are used in the solar air conditioning simulation. Validation of the developed simulation model was done with experiment data for solar air…

Actually, all rotating equipments which connected one to each other undergo a change in position during start-up (off-line) and this condition will affect the alignment of the shafts while running. The off-line to running movement characteristics of the vast majority of rotating machinery in industries have never been measured. It is very important to know how much movement occurred before concluding that it is insignificant and can be ignored. This paper will show the characteristics of both cold and hot misalignment. The purpose of this work is to analyze the influence of temperature to…

In ultrasonic nondestructive testing an ultrasonic wave is usually radiated through a material by a transducer. If there is a flaw inside the material, reflected or diffracted waves caused by the interaction between the ultrasonic wave and the flaw, are received by the same or another transducer. The received signals must be processed in order to obtain information about the flaw characteristics. For the flaw which perpendicular to the beam wave, the flaw size can be determined by amplitude analysis, for example by using DGS (Distance Gain Scale) diagram. The oblique flaw can be characterized…