# DRAKO fluid dynamic program

**D**ruckwellenberechnung in **R**ohrleitungssystemen mit **a**llgemeinen **Ko**mponenten

## Preface

DRAKO is a fluid dynamic computer program which calculates transient flow processes in complex piping systems.

Due to the large palette of components the program opens up an almost unlimited application spectrum on flow processes in arbitrary flow channels.

The program has a graphical user interface, which provides comfortable working during the generation of the calculation model and the evaluation of the results.

## Service range

Calculation of

- Liquids, steams and gases
- Two-phase flow
- Flashing, condensation
- Supersonic flow, detonation shock
- Wall elasticity
- Fluid-structure-coupling

## Boundary conditions

- Open/closed pipe ends
- Branches and tees
- Pressure function, mass flow function, area-time function
- Heat source as time function
- Safety valve, burst disc
- Check valve, setback valve
- Self-medium controlled valve
- Pump, air vessel, and so on

## Results

As results the program provides

- Active components (e. g. valve lift, pumping rotation speed, and so on)
- Pressure, speed, mass flow, density on chosen positions
- Pipe forces for later structure dynamic calculation

as functions over time.

## State equation

As fluids can be chosen in the program arbitrary liquids, two-phases mixture, steams or gases.

The material model for the appropriate fluid is formed from the following two functions:

- Density = f(pressure, entropy)
- Enthalpy = f(pressure, entropy).

To generate these two functions a database for water, steam und ideal gas is available.

## Solution method

In order to solve the differential equation system you can choose between

- The difference method of second order according to Mc. Cormack and
- The method of characteristics.