The following dimensionless groups are often used to presentdata on centrifugal pumps: flow coefficient = QD3, headcoefficient = gH2D2, power coefficient = W3D5, efficiency =gQHW , specific speed Ns = Q(gh)3/4, specific diameter Ds = Q(gh)1/4.Show that the last three groups can be formed from combinationsof the first three groups.
Cyclones and Anticlones • Cyclone o A center of low pressure o Pressure decreased toward the center o Winds associated with cyclone ▪ Northern hemisphere • Inward convergence • Counterclockwise ▪ Southern hemisphere • Inward convergence • Clockwise • Associated with rising air • Anticyclone o A center of high pressure o Pressure increases toward the center o Wind associated with an anticyclone ▪ Northern hemisphere • Outward divergence • Clockwise ▪ Southern hemisphere • Outward divergence • Clockwise • General atmospheric circulation o Underlying cause is unequal surface heating o On the rotating earth 3 pairs of atmospheric cells the redistributed heat o Idealized global circulation ▪ Equatorial low-pressure zone ▪ Subtropical high-pressure zone ▪ Trade winds ▪ Westerly winds ▪ Subpolar low-pressure zone ▪ Polar high ▪ Polar easterly/westerly o Influence of continents ▪ Seasonal temp differences disrupt • Global pressure patterns • Global wind pattern o Influence must originate in North Hemisphere ▪ Monsoon • Seasonal change • Circulation in the mid-latitudes o The zone of the westerlies o Complex o Air flow is interrupted by cyclones • Local wind
