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pressure

Compute the pressure due to a volume of gas.

Controller: lodmore

Contents

Interface
Pressure
Page Comments

Interface

C++

Excel

Pressure

doublepressure(	double	`p1`
	double	`v1`
	double	`v2`
	double	`gamma` `= 1.4`	)

Compute the pressure due to a change in volume of gas, based on the adiabatic expansion

$p_1 v_1^\gamma = p_2 v_2^\gamma$

(2)

Therefore

$p _1= p_2 \frac{v_2}{v_1}^\gamma$

(3)

where γ is the gas constant, equal to 1.4 for air.

Example 1

The follow graph show the change pressure when an initial 2m³ air is expanded or contracted:

There is an error with your graph parameters for pressure with options v1=2 p1=14.7 v2=0.1:4

Error Message:Function pressure failed. Ensure that: Invalid C++

Note

The units for pressure and volume can be interchanged with SI or Imperial systems, so long as the units used for p1 are the same as those in p2; and equally the units of v1 = v2. i.e. You are consistent.

Parameters

p1	The initial pressure [psi]
v1	The initial volume [ft³]
v2	The new volume [ft³]
gamma	The gas constant. Default value = 1.4 (for air)

Returns

The new pressure at volume v2. [psi]

Authors

James Bateman (March 2008)

Source Code

Source code is available when you agree to a GP Licence.

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