[AR] Re: Ultrasonic fluid level monitoring

  • From: Peter Fairbrother <zenadsl6186@xxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Wed, 16 Sep 2015 23:20:38 +0100

On 16/09/15 22:51, Eric Sims wrote:

I haven't been keeping up, but if this were intended for flight,
wouldn't the doppler effect be a big problem for many of these sensors?

No.

The sensor and the fluid surface have zero [1] relative velocity velocity whether on the ground or accelerating.


[1] apart from the changing fluid level, which you want to measure, of course.



The effects of acceleration [2] on the system would be negligibly small until the acceleration was great enough to cause the gas to noticeably stratify, ie get thicker at the bottom - which would be far, far, far more acceleration than any rocket makes, millions of g's or so.


[2] not the Doppler effect, which is caused by differing relative velocity, not by acceleration

-- Peter Fairbrother






-Eric

On Wed, Sep 16, 2015 at 4:15 PM, Uwe Klein <uwe@xxxxxxxxxxxxxxxxxxx
<mailto:uwe@xxxxxxxxxxxxxxxxxxx>> wrote:

Am 16.09.2015 um 21:24 schrieb Bruno Berger:

On rockets you have lots of other ultrasonic sources (Engine,
incoming
pressurant, airflow around the airframe ect.). I am pretty sure this
interferes with the sensor. Keep also in mind that speed of sound
depends on the root of the temperature of the gas (and that changes
quite during operation in a tank).


What about a looking up sensor arrangement?
the liquids properties should not change all that much.
and it is much easier to get good coupling into a denser fluid
than into gases.

Which leads us by the nose to
a bog standard marine echo sounder ;-?

uwe






Other related posts:

  1. Home
  2. arocket
  3. Archive
  4. 09-2015