I'm designing a probe to provide a stable and continuous stream of exhaust gas sample to an analyser. The probe has to be inserted into the exhaust for about 20–30 cm to keep outside air from entering the probe. The static pressure there is about 1000 Pa above atmosphere. The dynamic pressure is probably way higher. The material of the probe is brass.
The problem here is that the fluctations in the environment inside the exhaust may have significant influence on my sampling. The analyser precisely dilutes the exhaust gas to match the sensor's specs, and environmental changes may alter the dilution ratio, resulting in incorrect readings. The probe has to offer a sample at a pressure as constant as possible.
The pressure inside the exhaust will force exhaust gas into the probe, and with changing engine load, the temperature, static, and dynamic pressure will change, forcing a different amount of exhaust gas into the probe. I want to have that pressure as stable as possible, so that I can correct for it in my calculations.
I have tried to eliminate the influence of dynamic pressure, but I'm not sure if this is the best way to create a sampling of constant pressure.
So tl;dr, consider image above, is there a better way to offer samples of constant pressure, in an environment that has fluctuating static and dynamic pressure, and temperature?