Abstract
At present, regulations of automobile exhaust gas in each country are regulated by the total mass emission (g/km) of gas compounds, such as CO, THC, and NO_x. For measurement of mass emission, the CVS(Constant Volume Sampler) method has been in general use. However, as a result of the low emission levels of new engines, the CVS method in no longer able to meet today's requirement. The reason is that the CVS method requires a high dilution to prevent water condensation, this leads to measurement of very low gas concentrations, which results in worse accuracy. In consequence, it comes to need that exhaust gas concentration is directly measured in the tail pipe without diluting. This study focused on the flowmeters (Annubar^[○!R] flowmeter, vortex flowmeter, ultrasonic flowmeter) which are now used as exhaust gas flowmeters, and certificated the basic characteristics of these flowmeters at steady flow and pulsating flow.
