# Convert mm head to pascals

1. Nov 28, 2012

### escobar147

Referenced pitot pressure = 107 (mm) referenced static pressure = 525 (mm).......
find referenced dynamic pressure by subtracting static pressure from pitot pressure and converting to Pascals............

how on earth do you convert it to pascals?

2. Nov 28, 2012

### Staff: Mentor

They are just two measurements of pressure... mmHg and Pascals:

http://www.unit-conversion.info/pressure.html

.

3. Nov 28, 2012

### escobar147

4. Nov 28, 2012

### Staff: Mentor

What is the definition of "head" in the context of this problem?

5. Nov 28, 2012

### escobar147

it's the measurement of wake traverse behind anaerofoil, the pitot static tube is upstream and connected to a manometer, whilst the rest are pitot (stagnation) tubes and are located downstream and also connected to a manometer

6. Nov 28, 2012

### Staff: Mentor

And the tubes all measure air pressure, correct?

7. Nov 28, 2012

### escobar147

An aerofoil (chord c = 0.152 m; span b = 0.30 m; NACA 0012 section) is mounted in a drag
balance. A comb of Pitot and static tubes is mounted downstream of the aerofoil. Tubes
numbered 5, 12, 21 and 28 measure static pressure, while the rest measure Pitot (stagnation)
pressure. The tubes are connected to a multi-tube manometer, leaving four spare manometer
tubes (33-36). A Pitot-static tube is provided upstream of the model to measure free-stream
conditions and its two connections should be connected to two of the spare manometer tubes.
The manometer should be set at a low inclination (20º to the horizontal). Note that the
manometer is graduated in centimetres and contains fluid of specific gravity 0.784.
Measurements
(1) As in Part I, read the laboratory barometer and thermometer to determine the air
density and viscosity.
(2) With the wind tunnel running at maximum speed (both fans on), take the reference
pitot pressure (p0,ref) and static pressure (pref) upstream and convert the difference
from mm to Pa, noting the sign! Deduce the free-stream dynamic pressure