How to calculate the drag force
while the force required by the freighter to tow the barge is proportional to its speed, i.e.
F = CV, C is a constant, and P = CV * V is obtained by introcing p = FV
because when v = 20km / h, P = 40000kW, C = 100
that is, f = 100V * V = 100 * 10 * 10 = 10000kw
n= β FGN
note: β Considering the seismic action, the axial pressure increasing coefficient of the column is 1.3. 25)
fcalculate the load area of the column according to the simply supported state
G the representative value of gravity load in unit building area can be approximately taken as 14KN / m2
n is the number of floors above the checking section.
respectively http://www.cws.net.cn/Journal/SediRes/200205/11.pdf
where D, l, W is the area coefficient corresponding to the drag force, uplift force and underwater gravity, CdCl is the drag force and uplift force coefficient, UB is the velocity of flow acting on the bed sand, s is the volume weight of sand particles and water is the water density
in addition to the above forces, the additional mass forces e to the composition and relative exposure of non-uniform sand particles should also be considered
pressure flow is the flow of polymer melt in the pipe under the action of pressure, which is called pressure flow
the pressure flow hypothesis is a hypothesis about the transport mechanism of organic matter in phloem proposed by Minch, Germany its basic point is: the organic matter moves with the flow of liquid in the screen tube, and the power of liquid flow is the pressure potential difference at both ends of the transport system. Minxi explained this basic principle with a physical model. A and B are two osmometers, which are immersed in a and B water tanks respectively. Assuming that the osmotic potential in a is lower than that in B, the pressure will be established faster in osmometer a than in B. since two osmometers are connected through C, the pressure will be transmitted from osmometer a to B, and the solution will flow from osmometer a to B through C, which is called pressure flow. The result is that water enters permeameter a through the semi permeable membrane, and the solution in permeameter a continuously flows into permeameter B through C. water continuously seeps out from permeameter B through the semi permeable membrane until enough solute moves from permeameter a to permeameter B, so that the concentration and pressure potential of the two are equal, and the liquid flow stops. If solute is continuously added to osmometer A and removed from osmometer B to keep the concentration of solution in osmometer a higher than that in osmometer B, the liquid flow will continuously flow from a to B. Minxi pointed out that the living plant is similar to its designed model. The photosynthetic cells in the leaves are equivalent to osmometer a, and the growing parts or storage organs are equivalent to osmometer B, so that the pressure potential difference between the two ends can be maintained. However, the transport of organic matter is a complex problem, which can not be fully explained by this hypothesis drag flow is a part of the pipe structure, always moving at a certain speed relative to other parts, applied disciplines: Materials Science and Technology (first level discipline), polymer materials (second level discipline), polymer processing (third level discipline), processing related properties (fourth level discipline)
before towing, it is necessary to know the maximum bollard pull of the main tug and the drag of the towed object. The total resistance of the towed object = water resistance + wind resistance. All can be found on the drag curve of the towed object. When the maximum bollard pull * 75% of the tug is greater than (the total drag of the towed object + the towing force consumed by the main tug), it can meet the towing requirements.