Experimental Study On Flow Characteristics Of Pipeline Spiral Flow Containing PAM

The operation of slurry transportation in pipeline is the fifth-largest transportation method and is widely used in dredging,mineral transportation,natural gas extraction and other fields.However,the long-distance pipeline transportation in practical projects has the problems of large resistance,easy obstruction of sidement in pipeline whice cause the explosion of pipes.Establishing a circulating pipeline test system,and using a straight ball head 5-hole stylus and a set of water pressure measurement system in this experiment.Measuring the hydrostatic pressure in the wall of the pipeline spiral flow,and the hydrodynamic pressure in the measuring needle to analyze the effect of polyacrylamide(PAM)in pipeline spiral flow.First verify the reliability of the flow measurement system and pressure measurement system.Using the measured flow velocity to analysis the distribution law of the axial flow velocity and the circumferential velocity when PAM solution is 100 ppm.Using pressure value of the side wall,to analyze the pressure drop characteristics in pipeline and construct the drag reduction rate parameter.Using the effective spin distance(flow index)parameter,theoreticaly analysising the solidification capacity of the spiral flow in pipeline before and after adding PAM.Indirect measurement method(Preston method)was used to measure the one-dimensional flow wall shear stress with the help of five-hole straight ball stylus,and effective spin distance(mechanical index)was proposed,which is theoretically analyzed the helical flow solidification capacity.The results show that the measured value of the wall shear stress using the 5-hole stylus is 3-5%larger than statics of the Preston law.The five-hole stylus can be used to measure the shear stress of the one-dimensional in pipeline which is full of clean water.At the effect of PAM,the velocity distribution of the spiral flow in pipeline is different from data of clear water,and the "double peak" phenomenon appears in the axial velocity distribution.When the medium is clear water,the maximum circumferential velocity and the wall shear stress(circumferential component)increase with the increase of the flow rate,and decrease with the increase of the flow distance,and linearly decay at the 10-fold diameter.At the effect of PAM,the maximum circumferential velocity and wall shear stress(peripheral component)increase with the increase of flow rate,decrease with increasing flow distance and linearly decay at 20 times the diameter,making the developing process form formation stage to linearly decay stage extend by 100%,and the PAM can effectively increase the wall shear stress and the maximum circumferential speed.In addition,after the addition of PAM,the effective spin-up distance(mechanical parameters,flow rate parameters)respectively increase 100-150%and 80-90%,and drag reduction rate in the fully developed segment is 18-24%.It can be seen that adding PAM helps to reduce the resistance loss of the spiral flow in pipeline.In theory,it can increase the spiral flow solidification capacity of the pipeline.