I have couple of thoughts that need some input from others on.
Thought one:
How does one calculate the size and dimensions of a cyclone filter?
What is the criteria?
What is the cut size you try aim for?
Since nothing is ever going to be static the filter will never operate at maximum efficiency.
Second thought:
Vane type mass airflow sensors.
Who makes the smallest ones that could be adapted to feed a small engine gasifier?
Re: cyclones, I recommend reading the Handbook of Biomass Gasifier Systems, he’s got some good calculations on cyclone proportions. You aim for a certain cut size at the average flow rate. Above that rate, you get diminishing returns and too much drag. At lower flow rates, like at idle, you get less efficiency but there’s also less total dust load. It works out OK.