Surge tower, surge shaft
------------------------

SURGTW (class)
^^^^^^^^^^^^^^

.. figure:: ../media/image723.png
	:figwidth: 0.90625in
	:align: center
	
	Surge tower, surge shaft


**Supplier type**

+-----------------------------+--------------------------------------------------------------+--------+
| type label                  | Description                                                  | active |
+=============================+==============================================================+========+
| Surgetower constant area    | Storage area is independent of liquid height (pressure head) | No     |
+-----------------------------+--------------------------------------------------------------+--------+
| Surgetower height dep. area | Storage area is a function of liquid height (pressure head)  | No     |
+-----------------------------+--------------------------------------------------------------+--------+

.. _mathematical-model-33:

Mathematical model
""""""""""""""""""

A surge tower or shaft or open tank (atmospheric pressure above fluid level) with constant area supplies fluid to the system according to the differential equation:

.. math::

	Q=-A_{\mathrm{tw}} d H / d t

in which:

============ = ====================================== ===============
Q            = Discharge from the tower to the system [m\ :sup:`3`/s]
A\ :sub:`tw` = Storage surface of the tower           [m\ :sup:`2`]
H            = fluid level in the tower               [m]
============ = ====================================== ===============

In case the area of the surge tower is a function of height the following differential equation has to applied:

.. math::

	Q=-d V_{\mathrm{f}} / d t

in which:

=========== = ====================================== =============
V\ :sub:`f` = Volume of the fluid in the surge tower [m\ :sup:`3`]
=========== = ====================================== =============

In steady state the surge tower does not supply fluid. In that case the equation is simply:

.. math::

	Q=0

Surgetower constant area
^^^^^^^^^^^^^^^^^^^^^^^^

.. _hydraulic-specifications-37:

Hydraulic specifications
""""""""""""""""""""""""

=========== ===== ============= ======= ======= =======
description Input unit          range   default remarks
area        Real  [m\ :sup:`2`] (0-500]         
=========== ===== ============= ======= ======= =======

See also "Mathematical model" (:numref:`mathematical-model-33`).

.. _component-specific-output-35:

Component specific output
"""""""""""""""""""""""""

Fluid level [m]

.. _h-actions-33:

H-actions
"""""""""

None

.. _component-messages-32:

Component messages
""""""""""""""""""

None

Surgetower height dep. area
^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. _hydraulic-specifications-38:

Hydraulic specifications
""""""""""""""""""""""""

================= ===== ==== ===== =======
description       input unit Range default
================= ===== ==== ===== =======
height-area table                  
================= ===== ==== ===== =======

See also "Mathematical model" (:numref:`mathematical-model-33`).

**Example of table**

.. table:: Surge tower height dependent area.

	========== =========
	height (m) area (m2)
	========== =========
	2.50       25.0       
	4.00       25.0       
	5.00       10.0       
	7.00       10.0
	========== =========

.. figure:: ../media/image698.png
	:figwidth: 1.64583in
	:align: center
	
	Surge tower height dependent area

.. _component-specific-output-36:

Component specific output
"""""""""""""""""""""""""

Fluid level [m]

.. _h-actions-34:

H-actions
"""""""""

None

.. _component-messages-33:

Component messages
""""""""""""""""""

None

.. include:: substitutions_liquid.rst