Spring-Loaded Accumulator (IL)

A spring-loaded battery used to store energy in an isothermal liquid system.

blockType: EngeeFluids.IsothermalLiquid.Volumes.SpringLoadedAccumulator

Path in the library:

/Physical Modeling/Fluids/Isothermal Liquid/Tanks & Accumulators/Spring-Loaded Accumulator (IL)

Description

Block Spring-Loaded Accumulator (IL) simulates a spring accumulator in an isothermal fluid network. The battery consists of a preloaded spring and a liquid chamber.

When the liquid pressure at the battery inlet becomes greater than the preload pressure, the liquid enters the battery and compresses the spring. When the liquid pressure decreases, the spring releases and releases the accumulated liquid into the system. The movement of the separator is limited by a rigid stopper when the volume of liquid is zero or when the volume of liquid is equal to the capacity of the liquid chamber.

The fluid resistance at the inlet and spring characteristics such as inertia and damping are not modeled. It is assumed that the spring pressure is linear with respect to the volume of the liquid. The flow rate is positive if liquid enters the battery. The diagram shows a spring accumulator:

spring loaded accumulator 1

	The volume of liquid in the battery.
	The volume of the liquid chamber.
	Pressure at maximum capacity.
	The pressure in the liquid chamber is equal to the pressure at the battery inlet.
	Contact pressure of the rigid stop.
	The coefficient of stiffness of the stop.
	The coefficient of spring stiffness.
	The mass flow rate of the liquid entering port A.
	The density of the liquid in the liquid chamber.

Conservation of mass

The conservation of mass is described by the following equations:

if compressibility is taken into account:
if compressibility is not taken into account:

where

Conservation of angular momentum

The conservation of angular momentum is described by the following equation:

where

Variables

Use the parameter group Initial Targets to set the priority and initial target values for the block parameter variables before modeling. For more information, see Configuring physical blocks using target values.

Ports

Conserving

# A — isothermal liquid port
isothermal liquid

Details

isothermal liquid port, corresponds to the inlet to the accumulator. The flow rate is positive if the fluid enters the accumulator.

Program usage name

port

Parameters

# Liquid capacity — battery capacity
m^3 | um^3 | mm^3 | cm^3 | km^3 | ml | l | gal | igal | in^3 | ft^3 | yd^3 | mi^3

Details

The amount of liquid that the battery can hold.

Units	`m^3` \| `um^3` \| `mm^3` \| `cm^3` \| `km^3` \| `ml` \| `l` \| `gal` \| `igal` \| `in^3` \| `ft^3` \| `yd^3` \| `mi^3`
Default value	`8e-3 m^3`
Program usage name	`V_capacity`
Evaluatable	Yes

# Preload pressure — spring pressure
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

Spring pressure when the liquid chamber is empty.

Units	`Pa` \| `uPa` \| `hPa` \| `kPa` \| `MPa` \| `GPa` \| `kgf/m^2` \| `kgf/cm^2` \| `kgf/mm^2` \| `mbar` \| `bar` \| `kbar` \| `atm` \| `ksi` \| `psi` \| `mmHg` \| `inHg`
Default value	`1.0 MPa`
Program usage name	`p_preload`
Evaluatable	Yes

# Pressure at full capacity — spring pressure
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

Pressure on the spring when the liquid chamber is full.

Units	`Pa` \| `uPa` \| `hPa` \| `kPa` \| `MPa` \| `GPa` \| `kgf/m^2` \| `kgf/cm^2` \| `kgf/mm^2` \| `mbar` \| `bar` \| `kbar` \| `atm` \| `ksi` \| `psi` \| `mmHg` \| `inHg`
Default value	`3.0 MPa`
Program usage name	`p_max`
Evaluatable	Yes

# Hard stop stiffness coefficient — stiffness coefficient
Pa/m^3 | MPa/m^3

Details

The coefficient of rigidity of the contact pressure of the rigid stop in relation to the volume of liquid that has penetrated the stopper. Rigid limiters are used to limit the volume of liquid between zero and the volume of the liquid chamber.

Units	`Pa/m^3` \| `MPa/m^3`
Default value	`1e4 MPa/m^3`
Program usage name	`k_hard_stop`
Evaluatable	Yes

# Fluid dynamic compressibility — compressibility of the liquid

Details

Is it necessary to simulate a change in the density of a liquid due to its compressibility? If the parameter Fluid dynamic compressibility If it is switched on, then the changes related to the mass flow rate of the fluid in the unit are calculated in addition to the density changes related to pressure changes.

Default value	`true (switched on)`
Program usage name	`dynamic_compressibility`
Evaluatable	No