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Homework Help: Suitability of wheels/turbines for generating electricity or driving machinery.

  1. Jun 27, 2011 #1
    1. The problem statement, all variables and given/known data

    Discuss the suitability for generating electricity or directly driving mechanical machinery.

    High breast water wheel:
    Head/m 4.65
    Flow rate*/m3 s−1 1.0
    Power/kW 39.4
    Diameter/m 7.0
    Width or height/m 2.5
    Mass/kg 14 143
    Power-to-weight ratio/W kg−1 2.8

    This leads to the following additional data...
    Torque = 72572 Nm
    Angular momentum = 72572 Nms
    Rotational kinetic energy = 60.80 kJ

    Victor water turbine:
    Head/m 5.55
    Flow rate*/m3 s−1 0.8
    Power/kW 36.6
    Diameter/m 0.76
    Width or height/m 0.7
    Mass/kg 534
    Power-to-weight ratio/W kg−1 68.5

    This leads to the following additional data...
    Torque = 807.5 Nm
    Angular momentum = 807.5 Nms
    Rotational kinetic energy = 16.91kJ

    2. Relevant equations


    3. The attempt at a solution

    I'm thinking that a power output of 35-40kW (i.e. both of them) is suitable for small-scale electricity generation.

    However, to directly drive industrial machinery a high torque and angular momentum would be required, hence only the high breast water wheel is suitable for that task.

    There are 6 marks for this question, which seems rather a lot for such hand-wavery. Can anyone point out what I can do for greater detail, or where my logic may have gone wrong?

    Many thanks in advance!
  2. jcsd
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