Pressure sensors for measuring pressure field on the bottom of the planing hull?

Discussion in 'Hydrodynamics and Aerodynamics' started by Hildershavn, Oct 20, 2017.

  1. M&M Ovenden
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    M&M Ovenden Senior Member

    Hi Hildershavn,
    The aircraft wing project I spoke about was on a jet fighter for dynamic stall behavior (very fast response time). The transducers were installed in the fairing to avoid any lag due to hose length, and set up as Dcockey mentions. We collected 1200Hz data which provided the detail of what was happening over the leading edge. I'm pretty it's possible what you want to capture, but the engineering effort will be about how invasive it will be to your candidate hull.

    Mark
     
  2. Hildershavn
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    Hildershavn Junior Member

    as a suggestion, so if I was to put 9 small holes (or more for that sake) to a panel on the hull and have all these holes connected up and share one common pressure sensor, then I should be able to read the "average" pressure from these sensors? The ultimate goal for me is to have a pressure to add to my quasi-static strength analysis, so I am interested in the average for a panel( between ribs and struts). Do you have a recommendation for sensors I could use?
     
  3. Barry
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    Barry Senior Member

  4. DCockey
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    DCockey Senior Member

  5. gonzo
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    gonzo Senior Member

    The strain sensors can be calibrated by applying known forces.
     
  6. M&M Ovenden
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    M&M Ovenden Senior Member

    I thought you needed dynamic data , wanting to avoid the lag in hose lengths. My gut feeling is to avoid hoses as much as possible so you don't end up chasing air bubbles. Just a quick thought without actually knowing what you are after.
    Mark
     
  7. TANSL
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    TANSL Senior Member

    Excuse me if the question is irrelevant, but do you need to measure pressures or impacts?
     
  8. baeckmo
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    baeckmo Hydrodynamics

    In biomechanical testing of reaction forces from animal (specifically dogs) movements, I have come across pressure-sensitive "mats" with multiple sensors. I'll go back and see if I cab find where they were made. Perhaps useful over limited area regions.
     
  9. Hildershavn
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    Hildershavn Junior Member

    Yes, I do need to measure dynamic pressure, however, I would use the readings from multiple sensors on one panel to average the pressure used in my quasi-static analysis. But you are right to question my intentions here, because I think now that averaging the value from multiple pressure inputs could result in the loss off of information. It would be better to have all sensors work independently and use a filter on the raw data to calculate the average during post-processing instead.
     
  10. Hildershavn
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    Hildershavn Junior Member

    Well, I would use pressure sensors in a combination with strain gages and linear displacement sensors to find out the minimum timeframe relevant to average pressure for use in quasi-static fea simulation of the panel. A peak pressure lasting for a very short time period may not at all have a relevant impact on the hull as I understand it.
     
  11. gonzo
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    gonzo Senior Member

    Sharp peaks are relevant to structural studies. Think of an extreme, like a bullet-proof vest. It acts like a soft fabric when the velocity is low. When a bullet hits it at high velocity, it acts like a plate. Forces acting at high velocities will create stress risers because of the shear between the area being accelerated and the rest.
     
  12. jcamilleri
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    jcamilleri Junior Member

  13. Hildershavn
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    Hildershavn Junior Member

    True enough for a dynamic analysis. However, short impulse peak pressures will not necessarily transfer much energy to the structure if the structure is flexible enough. In a quasi-static analysis, peak pressures may be omitted. As with a torsion stick, when the torque is high enough the rod flexes, and because of the limited stroke of the air wrench only a little fraction of this torque is actually transferred to the nut/bolt head.
     

  14. gonzo
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    gonzo Senior Member

    I agree, there is a threshold for short peaks. However, there should also be a minimum threshold for amplitude, not just duration. I suppose it will be dependent on the material properties you are studying.
     
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