Tandem type multi-purpose crawler belt moving pump collaborative operation system

Abstract

The invention relates to the technical field of mobile pump collaborative operation, and particularly discloses a tandem type multipurpose crawler mobile pump collaborative operation system which is characterized in that the system acquires pressure data through a pressure drop capturing module and analyzes a pressure-bearing compensation value, and whether a low-pressure trap appears or not is judged; a margin analysis module is combined with the compensation efficiency coefficient to dynamically calibrate the collaborative cavitation margin; the cavitation trend is recognized based on the cavitation proximity by means of a controllable analysis module, and when cavitation forms positive feedback, hierarchical collaborative optimization is conducted on the moving pump; and finally, a coherence model of pressure pulsation and stress waves is established based on cavitation collapse characteristics through a conduction verification module, and a low-pressure trap improvement degree model is established to evaluate the improvement degree. According to the method, the cavitation fault of the series pump set can be prevented, pressure loss under complex working conditions can be dynamically adapted, and collaborative design and operation of the series pump set are optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of collaborative operation of mobile pumps, and in particular to a tandem multi-purpose crawler mobile pump collaborative operation system. Background Art

[0002] Mobile water pumps are widely used in urban waterlogging emergency drainage and industrial fluid transportation due to their high mobility and easy deployment. When the head or flow of a single pump cannot meet the demand, multiple pumps are often used in series operation. However, existing series mobile pump systems have the following technical bottlenecks in collaborative operation:

[0003] When pumps are operated in tandem, cavitation bubbles generated by the foreline pump can flow into the downstream pump along with the fluid, causing the required NPSH curve of the downstream pump to shift rightward, resulting in insufficient effective NPSH and causing cavitation damage. Existing technologies suppress cavitation through a single air supply method, but this approach is limited in air supply and expensive, making it difficult to adapt to emergency situations in mobile scenarios.

[0004] When cavitation forms positive feedback between series-connected pump groups, existing control strategies are unable to cut off the energy conduction path, resulting in worsening cavitation damage. Existing technologies lack hierarchical collaborative optimization strategies and topology reconstruction methods.

[0005] To this end, the present invention provides a tandem multi-purpose crawler mobile pump collaborative operation system. Summary of the Invention

[0006] The object of the present invention is to provide a tandem multi-purpose crawler mobile pump collaborative operation system to solve the above-mentioned background problems.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A tandem multi-purpose crawler mobile pump collaborative operation system includes the following modules:

[0009] Pressure drop capture module: used to collect pressure data when mobile pumps are working in series, analyze the pressure data for pressure compensation to obtain a pressure compensation value, and perform matching analysis based on the pressure compensation value. If there is a mismatch, it determines whether a low-pressure trap has occurred.

[0010] Margin analysis module: If a low-pressure trap occurs, it is used to perform collaborative cavitation margin analysis on the mobile pump, obtain the collaborative cavitation margin and compensation efficiency coefficient, and dynamically calibrate the collaborative cavitation margin in combination with the compensation efficiency coefficient;

[0011] Controllable analysis module: Based on the determined collaborative cavitation margin, it is used to analyze the cavitation proximity of the mobile pumps in series collaborative operation in combination with the cavitation bubble characteristics, obtain the cavitation proximity and determine the cavitation controllable trend;

[0012] Control optimization module: If the controllable trend of cavitation is positive feedback, the mobile pump series collaborative operation is hierarchically optimized through the jet parameters to extract the cavitation collapse characteristics in the collaborative cavitation.

[0013] Furthermore, the matching analysis is performed based on the pressure compensation value as follows:

[0014] Obtain the minimum safety pressure, theoretical pressure loss, and foreline pump outlet pressure when the mobile pumps are running in series, and calculate the pressure compensation value by combining the non-negative truncation pressure compensation equation;

[0015] Obtain the maximum compensation pressure that the system can provide when the mobile pumps are connected in series, calculate the deviation ratio between the pressure compensation value and the maximum compensation pressure, and obtain the compensation deviation ratio;

[0016] A comparison analysis is performed based on the compensation deviation ratio to determine whether the pressure compensation matches.

[0017] Furthermore, the method for determining whether a low-voltage trap occurs is:

[0018] If there is a mismatch, the front pump increases the pressure and performs pressure compensation. The change in the inlet pressure of the back pump before and after the pressure increase is collected to obtain the input increase amplitude.

[0019] Obtain the compensation amplitude of the pressure compensation performed by the foreline pump;

[0020] The input boost amplitude is compared with the compensation amplitude to obtain the compensation efficiency coefficient;

[0021] A nonlinear growth analysis is performed on the resistance loss and flow velocity along the flow path. If the flow velocity and the resistance along the flow path show nonlinear growth, the low-pressure trap is determined by combining the compensation efficiency coefficient to obtain the judgment result of the occurrence of the low-pressure trap.

[0022] Furthermore, the method for dynamically calibrating the collaborative cavitation margin is:

[0023] Obtain the current compensation efficiency coefficient and cooperative cavitation margin, and make a cooperative cavitation margin amplification determination;

[0024] If the safety factor needs to be amplified, the collaborative safety margin is multiplied by the inverse of the compensation efficiency coefficient to obtain the dynamically calibrated collaborative cavitation margin.

[0025] Furthermore, the compensation efficiency coefficient and the cooperative cavitation margin are obtained as follows:

[0026] Obtain the NPSH of the backing pump and the backing pump when the mobile pump is working together r The bubble flow consistency analysis is performed on the curve to determine the NPSH of the foreline pump. r Does the curve cause the NPSH of the subsequent pump? roffset of the curve;

[0027] Among them, NPSH r is the required NPSH;

[0028] If there is a NPSH for the subsequent pump r The curve shifts to the right, and the required NPSH r Correction is made to obtain NPSH r ';

[0029] Combined with the modified NPSH′ r and NPSH′ after right deviation pr , and perform difference calculation to obtain the collaborative cavitation margin.

[0030] Furthermore, the controllable trend of cavitation is determined as follows:

[0031] The proximity degree of cavitation of mobile pumps in series operation is analyzed by combining the characteristics of cavitation bubbles to obtain the cavitation proximity degree.

[0032] Based on the cavitation proximity, the expected value of the cavitation proximity component in the next k steps and the growth rate of the expected value of the cavitation proximity component in the next k steps are calculated through the dynamic system state space modeling method;

[0033] If the growth rate of the expected value of the cavitation proximity component in the next k steps is higher than or equal to the preset growth rate threshold, it is determined that the growth trend is worsening, and a transmission analysis of the multi-pump coordination trend is performed to determine whether cavitation forms positive feedback between the pump groups;

[0034] If positive feedback is formed, the controllable trend of cavitation will deteriorate sharply.

[0035] Furthermore, the transmission analysis of the multi-pump coordination trend is performed as follows:

[0036] Obtain the expected values ​​of the cavitation proximity components of the front pump and the back pump in the series pump in the next k steps, and perform cavitation gain transfer analysis to obtain the cavitation transfer gain;

[0037] Based on the transfer gain, it is determined whether cavitation forms positive feedback between the pump groups.

[0038] Furthermore, the hierarchical collaborative optimization is performed as follows:

[0039] Control the jet air supply of the front-stage pump to suppress the right shift of the NPSHr curve of the back-stage pump;

[0040] The jet unloading of the rear stage pump and the steady flow of the front stage jet are realized, and a collaborative optimization model is established to realize the control switching;

[0041] The series topology is reconstructed by jet bypass to isolate the cavitation positive feedback pump section.

[0042] A tandem multi-purpose crawler mobile pump collaborative operation system, further comprising:

[0043] Conduction verification module: Based on the cavitation collapse characteristics, the stress wave conduction of the mobile pump series collaborative operation is verified, the coherence function of the pressure pulsation and stress wave is obtained, and the trap improvement analysis is performed to obtain the low-pressure trap improvement degree and evaluate the improvement degree of the low-pressure trap.

[0044] Furthermore, the coherence function of the pressure pulsation and the stress wave is obtained and the trap improvement analysis is performed as follows:

[0045] Based on the characteristics of cavitation collapse, a coherence model of pressure pulsation and stress wave is established, and the coherence function is obtained;

[0046] Locate the coupling frequency band of the low-pressure trap region based on the high coherence frequency band;

[0047] Taking the coupled frequency band as the benchmark, the collapse characteristics before and after the hierarchical collaborative optimization are extracted;

[0048] Based on the collapse characteristics before and after hierarchical collaborative optimization, a low-pressure trap improvement model is constructed to obtain the improvement degree of the low-pressure trap.

[0049] Beneficial effects of the present invention:

[0050] (1) By collecting pressure data of mobile pumps in series operation, the pressure compensation mismatch state is identified based on pressure compensation analysis; the formation of a low-pressure trap is determined by analyzing the nonlinear growth of flow velocity and resistance along the flow path and calculating the compensation efficiency coefficient, which is beneficial to reducing the risk of the inlet pressure of the subsequent pump being lower than the critical value due to the aggravation of nonlinear resistance, and providing early warning for subsequent cavitation control;

[0051] (2) Through the safety margin amplification mechanism, it is helpful to reduce the problem of aggravated pressure loss caused by low-pressure traps, reduce the increase in cavitation threshold caused by bubble transfer, and improve the operational reliability of the pump group; based on cavitation proximity calculation and dynamic system state space modeling, the cavitation trend is predicted, and the cavitation characteristic correction mechanism is activated through the flow rate-resistance nonlinear criterion. Combined with the state transfer equation and state expected value analysis, the cavitation trend is predicted, and the cavitation controllability analysis is transformed from qualitative to quantitative. When the cavitation trend worsens, the control strategy can be triggered in advance, providing a real-time decision-making basis for hierarchical collaborative optimization;

[0052] (3) A pressure pulsation-stress wave coherence model is established based on the cavitation collapse characteristics to locate the low-pressure trap coupling frequency band. An improvement model is constructed based on the characteristic parameters before and after the hierarchical optimization to achieve a visual analysis of the cavitation energy conduction path, provide a quantitative basis for the optimization of the control strategy, reduce the cavitation intensity assessment error in the low-pressure trap area, and help improve the accuracy of the jet parameter adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention will be further described below with reference to the accompanying drawings.

[0054] Figure 1 This is a module diagram of a tandem multi-purpose crawler mobile pump collaborative operation system of the present invention;

[0055] Figure 2 It is a flow chart of pressure compensation determination;

[0056] Figure 3 It is a flow chart of a collaborative operation method of a tandem multi-purpose crawler mobile pump in the present invention. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0058] Example 1

[0059] See also Figure 1 As shown, the present invention is a tandem multi-purpose crawler mobile pump collaborative operation system, comprising the following modules:

[0060] Pressure drop capture module: used to collect pressure data when mobile pumps are working in series, analyze the pressure data for pressure compensation to obtain a pressure compensation value, and perform matching analysis based on the pressure compensation value. If there is a mismatch, it determines whether a low-pressure trap has occurred.

[0061] The pressure compensation value is obtained by analyzing the pressure data as follows:

[0062] Obtain the operating sequence of mobile pumps when they are running in series, and divide the mobile pumps into fore-stage pumps and post-stage pumps;

[0063] Preferably, the pressure compensation equation is obtained by non-negative truncation: P comp =max[0,P min -(P out -ΔP loss )] Get the pressure compensation value P comp ;

[0064] Among them, P out It is the outlet pressure of the foreline pump when the mobile pump is connected in series;

[0065] Through formula 1: Get the theoretical pressure loss ΔP loss ;

[0066] Among them, λ, L, ρ, v, D, g, and Δh are the pipeline's longitudinal resistance coefficient, pipeline length, fluid density, liquid flow rate, pipeline inner diameter, gravitational acceleration, and the elevation difference between adjacent pumps when mobile pumps work in series.

[0067] Through formula 2: P min =P υ +ρ*g*NPSH r +Ya obtains the minimum safety pressure P min ;

[0068] Among them, P υ NPSH r and Ya are the saturated vapor pressure of the fluid, the required NPSH of the pump, and the safety margin pressure respectively;

[0069] It should be explained that the pressure compensation value analyzes the connection stage between the outlet of the front-stage pump and the inlet of the back-stage pump, and the compensation matching of the pressure output of the front-stage pump to the pressure demand of the inlet of the back-stage pump;

[0070] It can be understood that the pressure compensation value is used to quantify the amount of pressure required to maintain the inlet pressure of the subsequent pump at or above the safety threshold when the series pump group is running, thereby preventing the risk of low-pressure traps and cavitation caused by insufficient pressure.

[0071] The purpose of calculating the pressure compensation value is:

[0072] Function 1: The pressure compensation value serves as a quantitative criterion for pressure compensation matching, supporting low-pressure trap warnings: The pressure compensation value calculated using the non-negative cutoff pressure compensation equation must be compared with the system's maximum compensation pressure to calculate the deviation ratio. If the deviation ratio exceeds the preset threshold, it indicates that the outlet pressure of the foreline pump cannot meet the minimum safety pressure requirement of the downstream pump after losses. At this time, the foreline pump is boosted and the compensation efficiency coefficient is analyzed. Combined with the nonlinear growth characteristics of flow velocity and along-the-line resistance, it can be determined whether a low-pressure trap has formed.

[0073] Function 2: Provide a data basis for the calibration of the collaborative cavitation margin and support cavitation risk control: When a low-pressure trap occurs, the compensation efficiency coefficient associated with the pressure compensation value will trigger the dynamic amplification mechanism of the collaborative cavitation margin. The system obtains the collaborative cavitation margin by correcting the required NPSH of the downstream pump and calculating the difference between it and the required NPSH after the right offset. When the efficiency coefficient corresponding to the pressure compensation value is insufficient, the margin value needs to be amplified by the safety factor to cover the additional pressure loss caused by nonlinear resistance. Ultimately, it provides a quantitative basis for hierarchical optimization strategies such as jet air supply control and topology reconstruction, thereby suppressing cavitation positive feedback.

[0074] Among them, the matching analysis method based on the pressure compensation value is:

[0075] Get the maximum compensation pressure P that the system can provide when the mobile pumps are connected in series comp,max , calculate the deviation ratio between the pressure compensation value and the maximum compensation pressure to obtain the compensation deviation ratio;

[0076] like Figure 2 As shown, the compensation deviation ratio is compared with a preset compensation deviation ratio threshold. If the compensation deviation ratio is lower than the preset compensation deviation ratio threshold, it is determined that the pressure compensation is matched, otherwise it is not matched.

[0077] If they do not match, the way to determine whether a low voltage trap has occurred is;

[0078] If they do not match, the front pump increases the pressure and performs pressure compensation, and collects the inlet pressure P of the back pump before and after the pressure increase. in The change of , the input boost amplitude is obtained;

[0079] Obtain the compensation amplitude of the pressure compensation performed by the foreline pump;

[0080] The input boost amplitude is compared with the compensation amplitude to obtain the compensation efficiency coefficient;

[0081] Perform nonlinear growth analysis on the resistance loss and flow velocity along the flow path. If the flow velocity and the resistance along the flow path show nonlinear growth, the low-pressure trap is determined by combining the compensation efficiency coefficient.

[0082] It will be understood by those skilled in the art that the data of fluid velocity and resistance along the flow path are collected and a curve fitting or differential analysis is performed to determine whether the resistance exhibits nonlinear characteristics as the flow velocity increases. For example, if the resistance growth rate exceeds the square of the flow velocity, it is shown that the resistance is related to the square of the flow velocity or a higher power.

[0083] When it is confirmed that the flow rate and the resistance along the process increase nonlinearly, if the compensation efficiency coefficient is lower than the preset threshold, it indicates that the compensation energy of the front-stage pump has not been effectively converted into an increase in the inlet pressure of the subsequent stage. In this case, it is determined that the system has formed a low-pressure trap. The nonlinear resistance aggravates the pressure loss, and the insufficient compensation efficiency leads to a lag in pressure compensation, which causes the risk of the inlet pressure of the subsequent stage pump being lower than the critical value.

[0084] Margin analysis module: If a low-pressure trap occurs, it is used to perform collaborative cavitation margin analysis on the mobile pump, obtain the collaborative cavitation margin and compensation efficiency coefficient, and dynamically calibrate the collaborative cavitation margin in combination with the compensation efficiency coefficient;

[0085] Among them, the method for determining the collaborative cavitation margin when the mobile pumps work in series is:

[0086] Obtain the NPSH of the backing pump and the backing pump when the mobile pump is working together r The bubble flow consistency analysis is performed on the curve to determine the NPSH of the foreline pump. r Does the curve cause the NPSH of the subsequent pump?r offset of the curve;

[0087] It will be understood by those skilled in the art that, first, under the same flow rate operating conditions, the required NPSHr curves of the downstream pump are collected when the foreline pump is without cavitation (bubble flow rate is 0) and with cavitation (bubbles are generated); the bubble flow rate is quantified by monitoring the bubble volume fraction at the foreline outlet, and the shapes of the downstream NPSHr curves under the two states are compared. If the foreline operates with bubbles, the downstream stage requires a higher NPSHr at the same flow rate, that is, the curve shifts to the right as a whole or rises locally, indicating that the bubbles generated by the foreline flow into the downstream stage, changing its gas-liquid two-phase flow field, resulting in a shift in the NPSHr curve.

[0088] If there is a NPSH for the subsequent pump r The curve shifts to the right, and the required NPSH r Correction is made to obtain NPSH r ';

[0089] Preferably, by the formula: Required NPSH for the downstream pump r Make corrections;

[0090] Among them, NPSH r0 、 NPSH when there are no bubbles r , α g is the bubble volume fraction, k and m are fitting coefficients related to bubble characteristics;

[0091] Combined with modified NPSH r The collaborative cavitation margin ΔNPSH is obtained by performing the difference calculation between ′ and the right-shifted NPSHr′. coop ;

[0092] Preferably, by the formula: ΔNPSH coop =NPSH r ′-NPSHpr′ to obtain the cooperative cavitation margin ΔNPSH coop ;

[0093] Where NPSHpr′ is the mean required NPSH for right offset;

[0094] It needs to be explained that the purpose of obtaining the collaborative cavitation margin is:

[0095] Purpose 1: Prevent cavitation failures in tandem pump sets. When tandem pumps are running, bubbles generated by cavitation in the foreline pump will reduce the effective vaporization pressure of the downstream pump, causing the required NPSH curve of the downstream pump to shift to the right. The collaborative cavitation margin modifies the NPSHr curve and combines it with the effective NPSH to quantify the system's safe distance against cavitation, which helps reduce cavitation damage caused by bubbles.

[0096] Objective 2: Dynamically adapt to pressure loss under complex working conditions. When a low-pressure trap exists in the series system, the pressure compensation efficiency of the foreline pump is insufficient. The collaborative cavitation margin is dynamically calibrated with the compensation efficiency coefficient to amplify the safety margin in real time, covering the cavitation risk caused by increased pressure loss and ensuring reliable operation of the pump group under variable working conditions.

[0097] Objective 3: Optimize the coordinated design and operation of tandem pump groups. Through coordinated cavitation margin analysis, we can guide the selection and matching of front-stage and rear-stage pumps, reduce the increase in the cavitation threshold of the rear-stage pump due to bubble transfer, and optimize the system layout to reduce low-pressure traps. Based on the dynamically calibrated margin value, we can monitor the cavitation risk of the pump group in real time, provide a quantitative basis for operating condition adjustment, and reduce equipment damage caused by blind operation of tandem pumps.

[0098] The method of dynamically calibrating the cooperative cavitation margin based on the compensation efficiency coefficient is as follows:

[0099] Obtain the current compensation efficiency coefficient and make a collaborative cavitation margin amplification determination;

[0100] It can be understood that the compensation efficiency coefficient is the ratio of the pressure compensation amount of the front-stage pump to the actual increase in the inlet pressure of the back-stage pump. If the compensation efficiency coefficient is less than 0.8, it indicates that the low-pressure trap has caused increased pressure loss, and the synergy margin needs to be amplified with a safety factor to cover the insufficient pressure compensation caused by nonlinear resistance.

[0101] If the safety factor needs to be amplified, the collaborative safety margin is multiplied by the inverse of the compensation efficiency coefficient to obtain the dynamically calibrated collaborative cavitation margin;

[0102] Example 2

[0103] like Figure 1 As shown, a tandem multi-purpose crawler mobile pump collaborative operation system also includes the following modules:

[0104] Controllable analysis module: Based on the determined collaborative cavitation margin, it is used to analyze the cavitation proximity of the mobile pumps in series collaborative operation in combination with the cavitation bubble characteristics, obtain the cavitation proximity and determine the cavitation controllable trend;

[0105] Among them, the method of analyzing the proximity of cavitation in mobile pump series collaborative operation by combining the cavitation bubble characteristics is as follows:

[0106] Through the nonlinear growth criterion of flow rate-resistance, it is judged whether there is nonlinear resistance loss in the series mobile pump. If it exists, the cavitation characteristic correction mechanism is activated to adjust the NPSH′ r Perform secondary correction to obtain NPSH″ r ;

[0107] It will be understood by those skilled in the art that if the resistance increases with the flow rate in a manner exceeding the first power, and presents a square or higher power correlation, that is, when the nonlinear resistance loss is determined to exist by the flow rate-resistance nonlinear growth criterion, the system activates the cavitation characteristic correction mechanism: based on the phenomenon of aggravated pressure loss caused by nonlinear resistance, combined with the influence of bubble transfer from the fore-stage pump on the flow field of the downstream pump, on the basis of the original required net cavitation head (NPSHr) correction model (such as the first-order correction formula considering the bubble volume fraction), a nonlinear resistance coefficient is further introduced to iteratively optimize the bubble volume fraction and the collapse frequency. By fitting the correlation curve between nonlinear resistance and bubble distribution, the corrected NPSHr of the downstream pump is recalculated to compensate for the additional cavitation risk caused by the nonlinear resistance, thereby achieving a secondary calibration of the collaborative cavitation margin.

[0108] By formula: Get cavitation proximity CR I;

[0109] Where, ΔNPSH coop NPSH r The cooperative cavitation margin calculated after the secondary correction;

[0110] Identify cavitation controllable trends through dynamic system state space modeling based on cavitation proximity;

[0111] Among them, the method of identifying the controllable trend of cavitation through the dynamic system state space modeling method is:

[0112] By constructing the cavitation state vector x(t) = [CRI(t), CRI′(t), Δσ(t)], the state transfer matrix A, input influence matrix B, control input vector u(t), and process noise vector w(t) are established based on the cavitation state vector;

[0113] Wherein, CRI(t), CRI′(t), and Δσ(t) are the cavitation risk index, the rate of change of the cavitation risk index, and the NPSH deviation, respectively, and t is the time;

[0114] It should be explained that the NPSH deviation is the difference between the effective NPSH and the required NPSH;

[0115] Combine the state transfer matrix A, input influence matrix B, control input vector u(t), and process noise vector w(t) to establish the state transfer equation x(t+1)=Ax(t)+Bu(t)+w(t);

[0116] The state transition equation is input into the particle filter algorithm to calculate the expected value E[CRI(t+k)] of the cavitation proximity component in the next k steps and the growth rate of E[CRI(t+k)] in the next k steps;

[0117] It will be understood by those skilled in the art that k represents the number of time steps for future prediction, that is, the number of discrete time intervals predicted from the current time t;

[0118] If the growth rate of E[CRI(t+k)] in the next k steps is higher than or equal to the preset growth rate threshold, it is determined that the growth trend is worsening, and a transmission analysis of the multi-pump coordination trend is performed to determine whether cavitation forms positive feedback between the pump groups;

[0119] Preferably, by the formula: Get the cavitation transfer gain G between series pumps with cavitation proximity ij ;

[0120] Among them, i and j represent the front pump and the back pump of the series pump group respectively;

[0121] Determine whether cavitation forms positive feedback between pump groups based on transfer gain;

[0122] For example, if the cavitation transfer gain Gij of the series pump group continues to increase, it indicates that cavitation forms a positive feedback between the pump groups, that is, the controllability trend of cavitation deteriorates sharply;

[0123] It can be understood that the cavitation transfer gain is the ratio of the change in the cavitation response of the downstream pump to the cavitation excitation of the fore-stage pump. In essence, it is a numerical mapping of the causal relationship strength of the cavitation between the fore-stage and downstream pumps.

[0124] The essence of judging the controllable trend of cavitation by cavitation transfer gain is to use it to quantify the amplification effect of the front-stage cavitation on the rear-stage in the series pump group. The cavitation transfer gain is the ratio of the change in the cavitation index of the rear-stage pump to the change in the cavitation index of the front-stage pump. If the gain is greater than 1, it indicates that the cavitation response of the rear-stage is stronger than that of the front-stage, and there is a positive feedback effect (such as the front-stage bubbles entering the high-pressure area of ​​the rear-stage accelerate their collapse, or the pressure pulsation superposition reduces the effective cavitation margin of the rear-stage). At this time, the controllable trend of cavitation worsens; when the gain continues to rise and exceeds the preset threshold, it means that the cavitation positive feedback has exceeded the local control capability, and it is necessary to intervene through graded strategies such as jet air supply and bypass topology reconstruction. Therefore, the dynamic change of cavitation transfer gain can directly reflect the propagation intensity and loss of control risk of cavitation between pump groups, providing a key quantitative basis for the judgment of controllable trend.

[0125] Control optimization module: If the cavitation controllable trend is positive feedback, the mobile pump series collaborative operation is hierarchically optimized through the jet parameters to extract the cavitation collapse characteristics in the collaborative cavitation;

[0126] Among them, the hierarchical collaborative optimization method of mobile pump series collaborative operation through jet parameters is as follows:

[0127] S1, control the jet air supply of the front pump to suppress the right shift of the NPSHr curve of the back pump;

[0128] Preferably, a micro air compressor is integrated on a mobile pump truck to extract and purify air from the environment, and the air supply volume is dynamically adjusted according to the transfer gain. The air is injected into the outlet pipe of the fore-stage pump through a Venturi-type axial nozzle at a pressure 0.15 MPa higher than the inlet pressure of the fore-stage pump, and the static mixer is used to disperse the air into microbubbles of 50 to 100 μm to form a uniform gas-liquid two-phase flow.

[0129] By monitoring the pressure pulsation spectrum of the downstream pump inlet and inverting the NPSHr curve offset, the air supply volume is corrected in real time to control the bubble volume fraction.

[0130] It can be understood that the bubble partial pressure effect and compressibility are used to buffer the pressure pulsation and suppress the right shift of the NPSHr curve of the subsequent pump caused by the cavitation bubble transfer of the previous stage;

[0131] S2, unloading the jet of the rear stage pump and stabilizing the jet of the front stage, and establishing a collaborative optimization model to realize control switching;

[0132] Preferably, an unloading jet with a flow rate of Qd is injected at the inlet of the subsequent pump to reduce the local pressure gradient by utilizing the vortex effect, and a steady flow jet with a velocity of 50% of the outlet velocity is injected axially 5D before the outlet elbow of the fore-stage pump to suppress flow velocity pulsation by stabilizing the flow field;

[0133] Among them, through the formula: Qd=k2*(G ij -1.5)*Q out,P2 Get the flow rate Qd of the unloading jet;

[0134] By formula: Establish a nonlinear correlation model G between unloading jet and transfer gain ij ';

[0135] Among them, k2 is the flow calibration coefficient of the unloading jet, G ij is the cavitation transfer gain, Q out,P2 is the outlet flow of the subsequent pump, k3 is the nonlinear suppression coefficient;

[0136] It can be understood that the role of establishing a nonlinear correlation model between the unloading jet and the transfer gain is:

[0137] Function 1: By establishing a nonlinear correlation model between the unloading jet and the transfer gain, the unloading jet flow rate is dynamically adjusted according to the real-time changes in the cavitation transfer gain. When the gain exceeds the threshold, the model can calculate the jet injection volume that matches the gain deviation and the main flow rate, so that the unloading jet intensity increases nonlinearly with the cavitation risk, reducing the hysteresis or excessive intervention of the linear control, and achieving the suppression of cavitation positive feedback;

[0138] Function 2: Utilize the nonlinear relationship to reflect the complex coupling between jet flow rate and cavitation transfer gain, adapt to the physical law that the proportion of kinetic energy in fluid mixing changes with the cube of flow rate, reflect the inhibitory effect of unloading jet on cavitation energy conduction path, provide the strategy switching for jet control and topology reconstruction, and improve the dynamic adaptability of cavitation control of series pump group;

[0139] It should be explained that k2 and k3 are obtained through experimental calibration and data fitting: a cavitation simulation model of the pump group is built to simulate actual operating conditions (such as pressure control and flow-induced cavitation), and data such as unloading jet flow and corrected gain under different cavitation transfer gains are collected; for conditions where the cavitation gain exceeds the threshold, k2 is obtained by linear regression fitting the proportional relationship between the jet flow rate, the gain excess, and the main flow rate;

[0140] k3 converts the exponential correlation into a linear form and fits the nonlinear suppression coefficient of the jet on the cavitation gain; the gain correlation value G output based on the nonlinear correlation model is ij ', to perform control switching;

[0141] It needs to be explained that when G ij ′≥1.5, start unloading and steady flow composite control, calculate G in real time ij ' decay rate, if G ij When ′ drops below 1.5, it switches to single-stage steady flow control, realizing the coordinated optimization of jet parameters and adaptive switching of control modes;

[0142] S3, reconstructing the series topology through jet bypass to isolate the cavitation positive feedback pump section;

[0143] Preferably, a jet bypass is set up beside the main pipeline of the series pump group, and a proportional solenoid valve is installed at the bypass inlet. When the cavitation transfer gain G is monitored, ij When the pressure is ≥2.0, the bypass flow rate is dynamically adjusted, and the bypass opening is increased from 0% to 50%-100% through PLC control, so that part of the fluid bypasses the cavitation positive feedback pump section, and the series topology is reconstructed into a front pump-bypass-back pump. The diversion effect of the bypass jet is used to reduce the direct coupling between pumps. At the same time, the pressure difference between the bypass and the main pipeline is monitored in real time through a pressure sensor, and the bypass opening is adaptively adjusted, which is beneficial to reducing the cavitation transfer gain and achieving isolation of the cavitation positive feedback pump section.

[0144] The extraction of cavitation collapse characteristics in cooperative cavitation includes: high-frequency pressure spikes generated by cavitation collapse, cavitation collapse frequency, and the mutation rate of cavitation transfer gain at the moment of cavitation collapse;

[0145] Conduction Verification Module: Based on the characteristics of cavitation collapse, the stress wave conduction of mobile pumps in series collaborative operation is verified, the coherence function of pressure pulsation and stress wave is obtained, and trap improvement analysis is performed to obtain the low-pressure trap improvement degree and evaluate the improvement degree of the low-pressure trap;

[0146] Among them, the stress wave transmission verification of the mobile pump series collaborative operation, the coherence function of the pressure pulsation and stress wave, and the trap improvement analysis are carried out as follows:

[0147] SS1. Based on the characteristics of cavitation collapse, a coherence model of pressure pulsation and stress wave is established to obtain the coherence function;

[0148] Preferably, the high-frequency pressure spike in the cavitation collapse characteristic is used as the excitation source, and the pressure pulsation and stress wave signals of the pump group flow channel and the structure surface are collected through the sensor array;

[0149] The pressure pulsation and stress wave signals are analyzed through cross-spectrum analysis to establish the coherence function of pressure pulsation and stress wave;

[0150] Based on the frequency distribution of the coherence coefficient, the high coherence frequency band corresponding to the high-frequency peak of energy conduction is determined;

[0151] It will be understood by those skilled in the art that the high-frequency pressure spike generated when the cavitation collapses is captured by a high-speed dynamic pressure sensor and used as the system excitation source;

[0152] High-frequency pressure sensor arrays and piezoelectric stress wave sensors are deployed at the impeller inlet and structural surface of the pump flow channel. A synchronous acquisition system is used to acquire time domain signals. After denoising and spectrum correction of the pressure pulsation signal and stress wave signal, the frequency domain correlation between the pressure pulsation signal and the stress wave signal is calculated using the cross-spectral density function to construct a coherence function.

[0153] Where, through the equation: Construct the coherence function Y 2 (f), where Sxy(f) is the cross-spectral density, Sxx(f) and Syy(f) are the self-spectral densities; based on the distribution curve of the coherence coefficient with frequency, Y is extracted. 2 The frequency band (f) ≥ 0.7 is a high coherence frequency band for efficient energy conduction. The high coherence frequency band corresponds to the dominant conduction path of cavitation collapse energy to structural stress waves.

[0154] SS2, a coupling band for locating low-pressure trap regions based on high-coherence frequency bands;

[0155] Preferably, locate low-pressure areas prone to cavitation (such as pump inlets, elbows, and impeller inlet edges); place high-frequency pressure and vibration sensors in these areas, collect signals, analyze their energy distribution within the highly coherent frequency band, and extract specific frequencies where the pressure pulsation peak and stress wave amplitude are significantly positively correlated;

[0156] SS3. Based on the coupled frequency band, extract the collapse characteristics before and after hierarchical collaborative optimization:

[0157] Preferably, the pressure peak amplitude, cavitation collapse frequency, and average mutation rate of cavitation transfer gain at the moment of cavitation collapse in the coupled frequency band before and after the hierarchical collaborative optimization are extracted to obtain the collapse characteristics before and after the hierarchical collaborative optimization;

[0158] SS4. Based on the collapse characteristics before and after hierarchical collaborative optimization, a low-pressure trap improvement model is constructed to obtain the improvement degree of the low-pressure trap;

[0159] Among them, the method of constructing the low-pressure trap improvement model is:

[0160] Calculate the relative change ratio of the pressure peak amplitude before and after hierarchical collaborative optimization to obtain the amplitude deviation rate;

[0161] Obtain the cavitation collapse frequency at the center of the coupling frequency band, calculate the deviation ratio between the cavitation collapse frequency before hierarchical collaborative optimization and the cavitation collapse frequency at the center of the coupling frequency band, and obtain the collapse offset ratio;

[0162] The attenuation ratio of the average mutation rate of the cavitation transfer gain before and after hierarchical collaborative optimization at the moment of cavitation collapse is calculated to obtain the gain suppression coefficient.

[0163] The amplitude change rate, collapse offset ratio, and gain suppression coefficient are summed to obtain the improvement degree of the low-pressure trap.

[0164] Based on the improvement degree of the low-pressure trap, the improvement degree of the low-pressure trap is evaluated.

[0165] Example 3

[0166] like Figure 3 As shown, a method for collaborative operation of a tandem multi-purpose crawler mobile pump includes the following steps:

[0167] Step 1: Collect pressure data when the mobile pumps are working in series, perform pressure compensation analysis on the pressure data to obtain a pressure compensation value, and perform matching analysis based on the pressure compensation value. If there is a mismatch, determine whether a low pressure trap has occurred.

[0168] Step 2: If a low-pressure trap occurs, perform a collaborative cavitation margin analysis on the mobile pump to obtain the collaborative cavitation margin and compensation efficiency coefficient, and dynamically calibrate the collaborative cavitation margin in combination with the compensation efficiency coefficient;

[0169] Step 3: Based on the determined collaborative cavitation margin and combined with the cavitation bubble characteristics, the cavitation proximity of the mobile pumps in series collaborative operation is analyzed to obtain the cavitation proximity and determine the cavitation controllable trend;

[0170] Step 4: If the cavitation controllable trend is positive feedback, the mobile pump series collaborative operation is hierarchically optimized through the jet parameters to extract the cavitation collapse characteristics in the collaborative cavitation;

[0171] Step 5. Based on the cavitation collapse characteristics, the stress wave transmission of the mobile pump series collaborative operation is verified, the coherence function of the pressure pulsation and the stress wave is obtained, and the trap improvement analysis is performed to obtain the low-pressure trap improvement degree and evaluate the improvement degree of the low-pressure trap.

[0172] The above is a detailed description of an embodiment of the present invention. However, the content is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A tandem multi-purpose crawler mobile pump collaborative operation system, characterized by: Includes the following modules: Pressure drop capture module: used to collect pressure data when mobile pumps are working in series, analyze the pressure data for pressure compensation to obtain a pressure compensation value, and perform matching analysis based on the pressure compensation value. If there is a mismatch, it determines whether a low-pressure trap has occurred. Margin analysis module: If a low-pressure trap occurs, it is used to perform collaborative cavitation margin analysis on the mobile pump, obtain the collaborative cavitation margin and compensation efficiency coefficient, and dynamically calibrate the collaborative cavitation margin in combination with the compensation efficiency coefficient; Controllable analysis module: Based on the determined collaborative cavitation margin, it is used to analyze the cavitation proximity of the mobile pumps in series collaborative operation in combination with the cavitation bubble characteristics, obtain the cavitation proximity and determine the cavitation controllable trend; Control optimization module: If the controllable trend of cavitation is positive feedback, the mobile pump series collaborative operation is hierarchically optimized through the jet parameters to extract the cavitation collapse characteristics in the collaborative cavitation.

2. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 1, characterized in that: The matching analysis is performed based on the pressure compensation value as follows: Obtain the minimum safety pressure, theoretical pressure loss, and foreline pump outlet pressure when the mobile pumps are running in series, and calculate the pressure compensation value by combining the non-negative truncation pressure compensation equation; Obtain the maximum compensation pressure that the system can provide when the mobile pumps are connected in series, calculate the deviation ratio between the pressure compensation value and the maximum compensation pressure, and obtain the compensation deviation ratio; A comparison analysis is performed based on the compensation deviation ratio to determine whether the pressure compensation matches.

3. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 1, characterized in that: The method for determining whether the low-voltage trap occurs is: If there is a mismatch, the front pump increases the pressure and performs pressure compensation. The change in the inlet pressure of the back pump before and after the pressure increase is collected to obtain the input increase amplitude. Obtain the compensation amplitude of the pressure compensation performed by the foreline pump; The input boost amplitude is compared with the compensation amplitude to obtain the compensation efficiency coefficient; A nonlinear growth analysis is performed on the resistance loss and flow velocity along the flow path. If the flow velocity and the resistance along the flow path show nonlinear growth, the low-pressure trap is determined by combining the compensation efficiency coefficient to obtain the judgment result of the occurrence of the low-pressure trap.

4. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 1, characterized in that: The method for dynamically calibrating the collaborative cavitation margin is: Obtain the current compensation efficiency coefficient and cooperative cavitation margin, and make a cooperative cavitation margin amplification determination; If the safety factor needs to be amplified, the collaborative safety margin is multiplied by the inverse of the compensation efficiency coefficient to obtain the dynamically calibrated collaborative cavitation margin.

5. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 4, characterized in that: The compensation efficiency coefficient and the cooperative cavitation margin are obtained as follows: Obtain the NPSH of the backing pump and the backing pump when the mobile pump is working together r The bubble flow consistency analysis is performed on the curve to determine the NPSH of the foreline pump. r Does the curve cause the NPSH of the subsequent pump? r offset of the curve; Among them, NPSH r is the required NPSH; If there is a NPSH for the subsequent pump r The curve shifts to the right, and the required NPSH r Correction is performed to obtain NPSH′ r ; Combined with the modified NPSH′ r and NPSH′ after right deviation pr , and perform difference calculation to obtain the collaborative cavitation margin.

6. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 1, characterized in that: The method for determining the controllable trend of cavitation is: The proximity degree of cavitation of mobile pumps in series operation is analyzed by combining the characteristics of cavitation bubbles to obtain the cavitation proximity degree. Based on the cavitation proximity, the expected value of the cavitation proximity component in the next k steps and the growth rate of the expected value of the cavitation proximity component in the next k steps are calculated through the dynamic system state space modeling method; If the growth rate of the expected value of the cavitation proximity component in the next k steps is higher than or equal to the preset growth rate threshold, it is determined that the growth trend is worsening, and a transmission analysis of the multi-pump coordination trend is performed to determine whether cavitation forms positive feedback between the pump groups; Among them, k represents the number of time steps for future prediction; If positive feedback is formed, the controllable trend of cavitation will deteriorate sharply.

7. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 6, characterized in that: The method for performing the transfer analysis of the multi-pump coordination trend is as follows: Obtain the expected values ​​of the cavitation proximity components of the front pump and the back pump in the series pump in the next k steps, and perform cavitation gain transfer analysis to obtain the cavitation transfer gain; Based on the transfer gain, it is determined whether cavitation forms positive feedback between the pump groups.

8. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 1, characterized in that: The method for performing the hierarchical collaborative optimization is: Control the jet air supply of the front-stage pump to suppress the right shift of the NPSHr curve of the back-stage pump; The jet unloading of the rear stage pump and the steady flow of the front stage jet are realized, and a collaborative optimization model is established to realize the control switching; The series topology is reconstructed by jet bypass to isolate the cavitation positive feedback pump section.

9. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 1, characterized in that: Also includes: Conduction verification module: Based on the cavitation collapse characteristics, the stress wave conduction of the mobile pump series collaborative operation is verified, the coherence function of the pressure pulsation and stress wave is obtained, and the trap improvement analysis is performed to obtain the low-pressure trap improvement degree and evaluate the improvement degree of the low-pressure trap.

10. The tandem multi-purpose crawler mobile pump cooperative operation system according to claim 9, characterized in that: The method for obtaining the coherence function of the pressure pulsation and stress wave and performing trap improvement analysis is: Based on the characteristics of cavitation collapse, a coherence model of pressure pulsation and stress wave is established, and the coherence function is obtained; Locate the coupling frequency band of the low-pressure trap region based on the high coherence frequency band; Taking the coupled frequency band as the benchmark, the collapse characteristics before and after the hierarchical collaborative optimization are extracted; Based on the collapse characteristics before and after hierarchical collaborative optimization, a low-pressure trap improvement model is constructed to obtain the improvement degree of the low-pressure trap.

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