Use JSN-sr04T transmitter and another in receiver

Hi,
I want to use 2 JSN-SR04T, one in transmitter and the other in receiver.
I want to use this model because it is stable and it resists a humid environment.
My goal is to measure the duration of the wave path (and to deduce the air velocity).
I try to separate transmitter and receiver on sr04, it's ok, however the sr04t (waterproof) uses a single transmitter / receiver.
I tried to send a wave to a 2nd receiver but it's KO.
Do you have an idea ? a solution to measure the movement of the wave, without a return trip?
thank you in advance
Daniel

Why do you not want to measure the speed of sound using the reflection travel time?

I would like to make an anemometer without moving parts for a boat.
If I measure a round trip of the wave, the wind speed is canceled. If I measure in both directions, I can calculate the wind speed and relativize the problems of temperature, pressure and humidity ...
And I would like to do it with an arduino ...

OK, I misunderstood the post. That is called a sonic anemometer, and there are a few DIY examples on the web.

This is very difficult project.

Yes, thank you. I know this link, I would like to simplify the construction using standard equipment if possible, even at the expense of consumption and accuracy, which can be average ...