Lecture 2 example, single tank hydraulic systemTutorialCurrent spec2:210 min

ENGR5001 Lecture 2 worked example 5, single tank hydraulic system (slides 26-28)

A tank of constant cross-sectional area AA is filled at volumetric flow rate QiQ_i and drains through an orifice near the base at flow rate QoQ_o. The liquid depth above the orifice is hh (see figure).

Single tank of area A, inflow Q_i at the top, head h, outflow Q_o through an orifice.
Single tank of area A, inflow Q_i at the top, head h, outflow Q_o through an orifice.
Formulas you may need
  • Conservation of volume (mass) for an incompressible fluid: Adhdt=Qi−QoA\dfrac{dh}{dt} = Q_i - Q_o (learn this)
  • Linear outflow assumption Qo=K′hQ_o = K'h (learn this)
  • Generalised first order form τdxdt+x=Ku(t)\tau\dfrac{dx}{dt} + x = Ku(t) (learn this)
  1. (a)
    State the assumptions used in the lecture model.
  2. (b)
    Derive a linear model relating the outflow QoQ_o to the inflow QiQ_i.
  3. (c)
    Put it into generalised first order form and give the time constant and steady state gain.