| Fracturing is an effective way to increase reservoir permeability and oil well productivity.Fracturing pump truck is one of the main equipment of fracturing technology.The main fracturing operation areas in China,such as Chuanqing oil field and Changqing oil field,have rough roads,and the space of fracturing construction site is limited.With the large-scale development of unconventional oil and gas,the fracturing pump truck is developing towards large-scale,heavy-duty,high-speed and high-pressure,which puts forward high requirements for the anti-vibration performance of fracturing pump truck frame and vibration reduction of fracturing pump system.Heavy load fracturing pump truck is a complex mechanical system,the vibration problem of the frame is complex,which reduces the service life of the frame,and even leads to fatigue fracture of the key structural parts of the frame,resulting in serious consequences.To research the vibration characteristic and vibration reduction technology of the frame of heavy-duty fracturing pump truck becomes an urgent problem for the development of large-scale fracturing system.In this paper,the modal parameter identification,vibration reduction technology,and experimental research of the frame vibration system of heavy-duty fracturing pump truck are carried out.This work is supported in part by the "Heavy Load Chassis Technology Research Project" which is the subproject of 12 th Five Year National Science and Technology Major Project "3000 Type Complete Fracturing Equipment Development and Application Demonstration Project"(No.2011ZX05048)and the "Chassis Modification Technology Research" which is the subproject of National High-tech Research and Development Program(863 Program)"2500HP Large Numerical Control Complete Fracturing Equipment Development"(No.2009AA063601).First of all,the random subspace model of the frame vibration structure is established to select the optimum test points.Combined with the stability diagram method,a modified deterministic random subspace identification method of the frame is proposed,and the structural modal parameter identification of the heavy-duty fracturing pump truck frame is realized by our proposed method.The calculation model of the superimposed beam of the main framework and the auxiliary framework was established,and the influence of slip effect is studied.The displacement and stress response distribution of the frame under different working conditions are studied by the finite element method.The dangerous points and test points of the frame of the fracturing pump truck are analyzed,and the arrangement scheme of strain gauge and acceleration sensor is made according to the actual working conditions of the heavy-duty fracturing pump truck.Secondly,several systematic tests on the strength and vibration characteristics of the frame of heavy-duty fracturing pump were carried out to solve the problems of abnormal vibration and insufficient strength and stiffness of the frame.Due to the noisy test data caused by the working environment of heavy-duty fracturing pump truck,an innovative fuzzy H∞ filter was developed to filter the test data.Test results of frame under parking condition shows that the high stress area is distributed in the lower area of the vehicle engine and gearbox;and the test data of driving condition shows that the maximum instantaneous stress of the frame appeared in two kinds of road conditions: single side ramp and raised barrier,and the maximum stress of the frame increased with the increase of the ramp slope and speed.The acceleration response test and modal analysis test of the frame are carried out,and the modal parameters are identified by using the stability diagram method and the random subspace method.It is found that the low-frequency vibration of the fracturing pump truck is the main factor causing the resonance.Based on the Euler beam theory and Mindlin Goodman theory,the solution method of the vibration response of the frame under the random road excitation is proposed,and a fatigue life estimation method of the frame is proposed.Thirdly,the fracturing pump is the main excitation source of the heavy-duty fracturing pump truck.The influence of the vibration response of the pump on the frame is investigated by test and numerical simulation respectively.The test platform of the fracturing pump system is built,the modal test and transient response test of the fracturing pump are carried out,the test results are analyzed,and the vibration response of the pump was treated as the excitation to the frame.Then,the influence on frame vibration and fatigue life is analyzed.The random state space model of the vibration and strain response of the frame of the 3000 fracturing pump truck under the original support boundary condition is established.The vibration of the fracturing pump under the working condition is used as the excitation source.The random subspace method of the strain mode analysis is used to identify the strain mode frequency of the frame under the actual constraints,and the dynamic response of the frame of the fracturing pump under different working conditions is calculated.The fatigue life of the frame under the operating mode was estimated.The layout adjustment scheme of installing equipment was proposed to reduce the vibration,which can effectively avoid the resonance region and significantly reduced amplitude.And the scheme has been used in type 3000-Ⅰ overloading fracturing pump truck.Finally,based on the Euler beam vibration theory and stability theory,a low-cost and high stability vibration reduction scheme of the fracturing pump truck frame is proposed,and a hydraulic support system at the cantilever beam of the rear of the truck is designed.Based on the system differential equation of the simplified model,the theoretical calculation formula of the transmission rate of the vibration isolator is derived,a new heavy load isolator suitable for fracturing frame is designed,and the static and dynamic response of the isolator is analyzed to verify its effectiveness.The hydraulic support system scheme and the isolator has been used in3000-Ⅰ overloading fracturing pump truck.This research results significantly reduces the overloading fracturing pump vibration,greatly promoted the new 3000-Ⅰ overloading the large-scale application of fracturing pump truck.As an important part of the "Development and Cluster Application of Ultra-High Pressure and High Power Oil and Gas Pressure Cracking Unit",this research achievement won the Second Prize of National Science and Technology Progress Award in 2015. |
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