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Spring-Loaded Accumulator - Simulate hydraulic accumulator with spring used for energy storage

Library

Accumulators

Description

This block represents a spring-loaded accumulator, where fluid entering the accumulator compresses the spring, thus storing hydraulic energy. Since the spring compression increases as fluid enters the chamber and decreases as the accumulator is discharged, the pressure is not constant. The spring is preloaded. Therefore, fluid starts entering the chamber only after the inlet pressure crosses over this threshold. The accumulator is described with the following equations:

where

`p`	Pressure at the accumulator inlet
`q`	Flow rate into accumulator
`V_max`	Accumulator capacity (maximum volume)
`V_F`	Instantaneous volume of fluid in the accumulator
`p_pr`	Preload pressure
`p_max`	Pressure needed to fully fill the accumulator

The block positive direction is from port A into the accumulator. This means that the flow rate is positive if it flows into the accumulator.

Basic Assumptions and Limitations

The model is based on the following assumptions:

The spring has linear characteristics.
No loading on the separator, such as inertia, friction, and so on, is considered.
Fluid compressibility is not taken into account.

Dialog Box and Parameters

Capacity: Accumulator volumetric capacity. The default value is 0.008 m^3.
Preload pressure: Pressure at which fluid starts entering the chamber. The default value is 1e6 Pa.
Maximum pressure: Pressure at which the accumulator is fully charged. The default value is 3e6 Pa.
Initial fluid volume: Initial volume of fluid in the accumulator. This parameter specifies the initial condition for use in computing the block's initial state at the beginning of a simulation run. For more information, see Computing Initial Conditions. The default value is 0.

Ports

The block has one hydraulic conserving port associated with the accumulator inlet.

The flow rate is positive if fluid flows into the accumulator.