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For major water-conveying and irrigation canals in gently sloping terrain, it has been found preferable to use pmnp stations with horizontal-axis units operating under heads of 3-12 m. The transient phenomena of these stations have several features, one of which is the relatively high rise in head at different stages of starting and stopping the pump under a head corresponding to the characteristic optimum. This circumstance causes an increase in vibration and dynamic loading and thd risk of unstable pump operation.The head rise above the design value during transitional regimes, together with other factors, is determined by the design of the discharge structure and the nature and form of the universal characteristic diagram of the pump.With regard to the fact that dynamic loadings on the pump unit during the transient phenomena rise by several times compared with working regimes and that the volume of constructlon-erectlon work on the dlscharEe structure can amount up to 10-15Z of the total for the whole statlon= a reduction in the dynamic loads on the unit and the volome of the discharge structure is very pressing. Possible alternative solutions of these problems will be examined for pumping stations of the Dnepr-Donhas (Donets Coal Basin) Stage 1 type (Fig. i).The starting operation of a horizontal axial pump delivering into a short conduit with a gate in the discharge structure can be nominally divided into three stages: 1--switching on the electric motor until the instant of synchronizatlon~ 2 --filling the gate forebay up to the design level of the upper pool (V UP) downstream of the gate; 3 --from the cu,a=encement of filling the gate forebay to the design level of the upper pool, up to full gate opening~ at this instant the pump operates under an increased head. Depending on the starting time and the rate of gate raising, the water may either accumulate in the gate forebay, flow under the gate, or spill over it. Fig. 2 are variations of the hydrotechnlcal parameters of pump OPG-220G during the starting operation. Presented inIn the first stage, over a period of 5-7 sec, the pressures on the suction and dellvery sides of the rotor (Psu, Pd ) drop considerably, falling to a minimum during synchronization of the motor. Pressure fluctuations on the delivery side of the rotor (2Ad) and the relative vibration of the rotor chamber (S/S o t) increase with the P rotational speed~ and reach a maximum at the instant of synchronization. As full-scale tests indicated, the maximum heating vibration depends little on the rotor-blade regulating anglei however= it tends to diminish at average angles of blade installation.The illustration also shows radial vertical vibration displacements of the stiffening ribs on the pump runner axis~ the vibration displacwnants of the chamber being greatest compared with the changed values at other points of the pump unit. The nature of the variation in chamber vibratlon is similar to that in pressure fluctuatlon~ and has the same blade frequency as the pressure fluctuation.~n the second...

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