Pressure Drop for Compressible Flow

From: <indra>
Date: Mon Jan 28 2008 - 00:56:00 EST

Hi all,

   First of all, my background is Mechanical Engineering, so most of the time I'm only working with incompressible fluid. However, this time I've given a task to calculate pressure drop of compressible fluid along pipeline connected to safety valve (flow is from steam drum to safety valve to pipeline to atmosphere).

   I'm assuming isothermal compressible flow. Using pressure and temperature at the safety valve's discharge point I obtain the fluid properties (density, viscosity, Cp, Cv, etc). Afterwards, my step-by-step calculation is as follows:

• Check for Mach number of inlet fluid: max possible velocity of a compressible fluid in a pipe is sonic.
• Calculate friction loss using Reynolds number and relative roughness
• Calculate loss coefficient due to fittings using Darcy's 3-K method
• Calculate total loss (friction loss + loss due to fittings)
• Calculate outlet pressure using Darcy's equation for compressible fluid
• Get the pressue drop (Inlet pressure - Outlet pressure)
• Check for Mach number of outlet fluid: max possible velocity of a compressible fluid in a pipe is sonic.

   Please let me know if my method is correct and complete enough to solve the problem. Thanks.

   Regards,

• Indra - Engineer, Singapore

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[Non-text portions of this message have been removed] Received on Mon Jan 28 00:56:00 2008