Academic Journal of Science and Technology ISSN: 2771-3032 | Vol. 3, No. 2, 2022 118 Experimental Study on Leakage Pressure Drop of Simulated Airport Oil Supply Pipe Network Yihao Lv* Xi’an Shiyou University, Xi’an 710065 China *Corresponding author: Yihao Lv Abstract: In order to simulate and study the change of pressure drop after the leakage of airport oil supply pipeline network, a set of simulation system of airport oil supply pipeline network leakage was built. The tightness of the system was tested based on the medium kerosene. The accuracy of the calculation model was verified quantitatively and qualitatively, and the leakage pressure drop calculation model under pressure and temperature was established. The results show that the tightness of the test system is good. Under the condition that the pressure remains unchanged, the leakage pressure difference decreases with the increase of temperature, which is consistent with the theory. The coefficient of determination of the data obtained from the test data and the calculation model can reach 0.9947, and the root mean square error can reach 0.0007075, with good accuracy. Keywords: Airport pipe network, Leakage, Pressure drop. 1. Introduction Due to the advantages of low cost, energy saving, high safety and stable supply, pipeline transportation is widely used in large and medium-sized airports at home and abroad. However, due to long-term operation corrosion and wear, equipment aging and natural disasters, leakage accidents of airport oil supply pipe network occur from time to time. On the one hand, the leakage of kerosene will cause the waste of resources, on the other hand, the leakage of kerosene in the open fire is prone to explosion accident, a serious threat to people's safety. Therefore, it is very important to study the pipe network to close the valve in time to avoid further damage when leakage occurs. During the pipeline construction process, a cut-off valve is set to cut off leaks by identifying transmitted pressure drop signals. In view of the research on leakage pressure drop, Liao Yupeng et al. artificially studied the pressure drop rate of gas storage gas production trunk, established the pipeline leakage model by using simulation software, and obtained the influence of the volume, compression ratio, and the distance between the valve chamber and the compressor on the pressure drop and duration of the valve chamber under the condition of compressor pumping. Yang Yi et al. established a gas pipeline leakage simulation model through simulation software, and obtained the relationship between pressure drop and duration of cut-off valve in valve chamber downstream of leakage point. Huang Wen et al. studied the pressure drop characteristics of aviation kerosene in a U-tube under supercritical condition, and proposed a frictional drag coefficient correlation formula modified by pressure and temperature, with a relative error of about 6.5%. To sum up, leakage pressure drop is mainly concentrated in long-distance gas transmission pipeline research, and because of the complexity of field tests, simulation software is often used to simulate. In order to study the change of leakage pressure drop of airport oil supply pipe network, this paper built a set of simulation of leakage pressure drop of airport oil supply pipe network. Based on the reliability of data and the accuracy of calculation model, the change of leakage pressure drop under different temperature and pressure states was studied. 2. Test System The structure of the experimental system is shown in Figure 1. The test liquid uses No.3 jet fuel. The whole experimental device is mainly composed of six parts: main pipeline module, pressurization module, temperature control module, leakage control and measurement module, data measurement and acquisition module, and data analysis and storage module. Test system of pressurized module and temperature control module is used to adjust and control the pressure and temperature of main line, when the pressure and temperature of test condition, adjust the leakage control and measurement module, real time measuring the actual leakage of kerosene in the subject line, data measurement and real- time acquisition module will kerosene in the subject line of pressure and temperature signal transmission to the data analysis and storage module, The theoretical leakage is obtained by calculation. 119 罐体 The water tank Suppression of pump Ball valve PTTT Temperature sensor Pressure transducer transducer Needle valve Measuring cylinder Data acquisition control cabinet Temperature control unit With tropica l Electroni c balance Flow rate regulatorComputer Infusion hose Figure 1. Process diagram of the test system 2.1. Main Pipe module The main pipeline module is composed of stainless steel tank, ball valve and needle valve. The tank is composed of stainless steel with wall thickness of 3 mm, inner diameter of 213 mm and pipe length of 1.8 m. As a leakage detection unit, it simulates the airport oil supply pipeline. Ball valves (DN40 mm) and needle valves (DN15 mm) are connected to the tank to control the inflow and outflow of fluid. 2.2. Booster Module The pressurization module is a high-pressure pressure pump device, which is connected with the ball valve at the bottom of the pipeline to pressurize the pipeline. 2.3. Temperature control module The temperature control module adopts the automatic tracking belt with length of 10 m and power of 80 W/m, which is used to simulate the field temperature. The temperature range can be achieved from room temperature to 50℃. 2.4. Leakage control and measurement module The leakage control and measurement module is composed of leakage hose, measuring cylinder and electronic balance, which is used to control and measure the leakage amount of real fluid. The leak hose includes an infusion hose and a flow rate regulator. The measuring range of the cylinder is 100 mL±1. The range of electronic balance (FA2204C) is 0-200 g, and the accuracy is 0.1 mg. 2.5. Data measurement and collection module The data measurement and acquisition module is composed of pressure sensor, temperature sensor, data acquisition control cabinet and computer. The range of pressure sensor is 0-2 MPa, and the accuracy is 0.2. Temperature sensor in the range of 0-100 ℃, the precision for grade A + (0.15 + 0.002 | | t) ℃. The data collection control cabinet encapsulates serial port I/O networking modules and power supplies. 2.6. Data Analysis and Storage Module The data analysis and storage module is composed of OPCServer, PNS and MySOL database. OPCServer communicates with the data acquisition facility. PNS connects to OPCServer through OPC protocol and publishes data based on OPCServer for real-time analysis. At the same time, the analysis results are stored in the MySQL database. 3. Kerosene Leakage Rate Model Based on the principle of mass conservation, when the tank is sealed, the total mass of the unit medium in the constant volume tank can be expressed as a function of temperature and pressure:  ,W V P T (1) The total mass of the element medium is differentiated in time, and the change of the total mass of the element medium is:         0 0 0 0, , d VdW Vd dt dt dt d W V dt V dt W V P T V P T                     (2) Therefore, in the leakage process, the leakage rate of the unit medium in τ time can be expressed as follows.        0 06 30 0 0 0 , , 3.6 10 , / ,i d V dt P T P TdtW Q L h m W V P T                i i (3) Where, W is the total mass of unit medium, kg; V is unit 120 volume, m3; ρ is the average density of unit medium, kg/m3; P is the average pressure of unit medium, MPa; T is the average temperature of unit medium, ℃; τ is the detection time, s. 4. Kerosene Closed Experiment 4.1. Measurement of kerosene density Petroleum densitometer and constant temperature water bath device were used to measure the standard density of kerosene. The experimental steps were as follows: (1) Start the constant temperature water bath device and adjust its temperature to 20℃; (2) Put kerosene into the measuring cylinder, gently put it into the constant temperature water bath box, and stand for 5 minutes to make it reach thermal balance with the temperature of the water tank; (3) Put the glass petroleum densitometer gently into the measuring cylinder and read after it is stable. The multiple measurement data are shown in Table 1, and the average value of all the data is 776.9 kg/m3. Table 1. Standard density measurement data The number of First time Second time Third time Fourth time Fifth time Density / kg/m3 776.2 775.0 777.5 778.3 777.4 Based on the standard density of kerosene ρ20, based on the calculation method of No. 3 aviation kerosene volume temperature correction coefficient Ctl, dynamic measurement of petroleum and liquid petroleum products, and oil volume pressure correction coefficient Cpl, the density calculation model of kerosene can be obtained, and the model can be used to calculate the kerosene density at other temperatures and pressures. Corroborate the reliability of the test data. 4.2. Kerosene tightness test In order to prevent leakage in the simulation system, the density calculation model mentioned above was used in the test to study the pressure changes with the detection time in four different temperature ranges: 14.6-16.6 ℃, 16.7-18.5 ℃, 18.5-20.1 ℃ and 20.0-21.9 ℃. 5. Kerosene Leakage Test In order to analyze the reliability and rationality of the experimental data, the law analysis is carried out according to the theoretical model. Figure 2. Theoretical values of 1-hour leakage pressure difference with temperature at 0.1 L/h/m3 leakage rate under different initial pressures FIG. 2 shows the theoretical value of 1-hour leakage pressure difference with temperature for 0.1 L/h/m3 leakage rate under different initial pressures. As can be seen from the figure, under the condition that the pressure remains unchanged, the leakage pressure difference gradually decreases as the temperature increases. Under the condition that the temperature remains unchanged, the leakage pressure difference has a small change with the increase of pressure. This law is mainly caused by low compressibility and high thermal expansion of kerosene and other liquid fuels. Then, the leakage pressure difference under different leakage duration at 0.1 L/h/m3 leakage rate was tested, and the relationship between the theoretical leakage pressure difference and the experimental leakage pressure difference was compared. 5.1. Kerosene sealing test results and analysis Under four different conditions, the pressure changes of each 1 ℃ change in temperature are 0.581 MPa/℃, 0.562 MPa/℃, 0.552 MPa/℃ and 0.531 MPa/℃, respectively. As can be seen from the figure: with the increase of the detection time, the temperature and pressure will show the same growth trend; As the temperature range increases, the pressure variation will gradually decrease. 90 95 100 105 110 115 10 15 20 25 30 35 40 P /k P a T/℃ 1.3MPa 1.0MPa 0.5MPa 0.3MPa 121 a b c d Figure 3. The relationship between temperature and pressure in different temperature ranges Will be four different temperature range of kerosene density changes in the data statistics as shown in the table 2, it can be seen from the table that the temperature range, the greater the kerosene calculation error, the greater the density model, when the temperature constant, the density model to calculate minimum error, also illustrates the system tightness is good, in the case of temperature changes smaller, kerosene density model accuracy of calculation is reliable. Table 2. Calculation results of closed experimental data of kerosene density model Range of temperature variation /℃ The initial density The end of the density Density difference Leak rate 14.6 16.6 781.8266 781.2606 0.566 0.5947 16.7 18.5 780.2289 779.5984 0.631 0.534628458 18.5 20.1 778.9228 778.1833 0.739 0.431540227 20.0 21.9 777.6955 776.8442 0.851 0.135010883 5.2. Kerosene leakage test results and analysis It can be seen from Table 3 and Figure 4 below that the leakage pressure difference is basically in direct proportion to the leakage duration when the pressure and temperature remain unchanged within the range of one hour. Table 3. Leakage pressure difference data under different leakage duration at 0.1 L/h/m3 leakage rate The temperature /℃ Pressure /MPa Leakage pressure difference at different times /MPa 10 min 20 min 30 min 60 min 10 1.3 0.0187 0.0374 0.0562 0.11256 1 0.0187 0.0374 0.0562 0.11261 0.5 0.0187 0.0375 0.0563 0.11271 0.3 0.0187 0.0375 0.0563 0.11275 20 1.3 0.0174 0.0348 0.0523 0.104806 1 0.0174 0.0349 0.0523 0.104866 0.5 0.0174 0.0349 0.0524 0.104966 0.3 0.0174 0.0349 0.0524 0.105006 30 1.3 0.0162 0.0325 0.0487 0.097589 1 0.0162 0.0325 0.0487 0.097649 0.5 0.0162 0.0325 0.0488 0.097749 0.3 0.0162 0.0325 0.0488 0.097789 40 1.3 0.0151 0.0303 0.0454 0.090868 1 0.0151 0.0303 0.0454 0.090928 0.5 0.0151 0.0303 0.0454 0.091028 0.3 0.0151 0.0303 0.0455 0.091068 122 Figure 4. Positive ratio between leakage pressure difference and leakage duration (taking 10℃,1.0 MPa, 40℃,0.5 MPa as an example) For the leakage process of airport pipe network, the 1-hour leakage of 1 m3 volume of oil is 0.1L, and the leakage under the experimental system is only 6.42ml, and its value decreases with the shortening of the leakage time, so it is difficult to measure or the measurement error is greater. Therefore, the leakage test data were analyzed by the 1-hour leakage duration, and the leakage pressure difference under other leakage durations was obtained by proportional conversion. In order to reduce errors, the data of the three groups of repeated leakage experiments were sorted out, and the mean value was taken as the final experimental data (see Table 4), which was compared and analyzed with the theoretical data. Table 4. Experimental data of aviation kerosene leakage (orthogonal table of pressure and temperature) 0.1 L/h/m3 1 h Leakage of pressure drop Absolute pressure /MPa 0.445 0.7 1 1.3 Temperature /℃ 10 0.072725 0.072696 0.081500 0.091814 14 0.065892 0.065133 0.072812 0.078351 17 0.063321 0.062626 0.069082 0.073016 18 0.062732 0.062152 0.067773 0.071849 21 0.061222 0.061569 0.067117 0.070051 23 0.059894 0.061091 0.065185 0.067534 28 0.059494 0.060063 0.064290 0.067227 30 0.054480 0.057279 0.062575 0.066203 32 0.053910 0.057045 0.061802 0.064287 34 0.052180 0.055520 0.060410 0.062136 36 0.050825 0.054849 0.058960 0.060752 38 0.047930 0.054140 0.056765 0.057684 40 0.047763 0.051849 0.053728 0.057439 Qualitative analysis: As can be seen from FIG. 5, when the pressure remains unchanged, the leakage pressure difference decreases with the increase of temperature, and its regularity is consistent with the theory. Under the condition that the temperature remains unchanged, the leakage pressure difference increases with the increase of pressure, and the variation range is larger than the theoretical value. 0 0.02 0.04 0.06 0.08 0.1 0.12 0 20 40 60 80 L ea ka ge o f th e di ff er en ti al /M P a Leakage length/min 10℃，1.0 MPa 40℃，0.5MPa 123 Figure 5. Variation of leakage pressure difference with temperature under different pressures Quantitative analysis: the theoretical value corresponding to Table 4 was calculated by using the model (see Table 5), and the deviation was obtained by comparing with the experimental data. Its average absolute deviation is 0.0378 MPa, the maximum deviation is 0.044474 MPa (temperature 17℃, pressure 0.7MPa), the minimum deviation is 0.020686 MPa (temperature 10℃, pressure 1.3 MPa) Table 5. Calculation data of aviation kerosene leakage model (orthogonal table of pressure and temperature) 0.1 L/h/m3 1 h Leakage of pressure drop Absolute pressure /MPa 0.445 0.7 1 1.3 Temperature /℃ 10 0.112600 0.112600 0.112500 0.112500 14 0.109500 0.109400 0.109400 0.109300 17 0.107200 0.107100 0.107000 0.107000 18 0.106400 0.106300 0.106300 0.106200 21 0.104100 0.104100 0.104000 0.104000 23 0.102700 0.102600 0.102600 0.102500 28 0.099100 0.099000 0.099000 0.098900 30 0.097700 0.097600 0.097600 0.097500 32 0.096300 0.096300 0.096200 0.096100 34 0.094900 0.094900 0.094800 0.094800 36 0.093600 0.093500 0.093500 0.093400 38 0.092300 0.092200 0.092200 0.092100 40 0.091000 0.090900 0.090900 0.090800 Through the fitting of table data and comparative analysis, the final fitting result is shown in Equation (4), and the fitting index calculated is: R2=0.9947, RMSE=0.0007075. 3 2 3 4 2 3 2 4 2 5 3 3 3 5 2 2 6 3 7 4 (x, y) 0.1799 0.2458 9.656 10 0.329 4.337 10 4.526 10 0.1072 0.01017 1.819 10 1.263 10 2.923 10 2.705 10 2.686 10 1.263 10 f x y x xy y x x y xy y x y x y xy y                                 (4) 6. Summary In this paper, the relationship between density change and leakage pressure difference of No.3 jet kerosene in the simulation system and leakage time is studied through experiments, and the influence law of temperature and pressure on leakage pressure drop is obtained. (1) The larger the range of temperature variation, the larger the error of kerosene density model calculation. When the temperature remains constant, the smaller the error of density model calculation. (2) Within 1 hour, under the condition that the pressure and temperature remain unchanged, the leakage pressure difference of the system is basically in positive proportion to the leakage time. (3) Under the condition that the pressure remains unchanged, the leakage pressure difference decreases with the increase of temperature, which is consistent with the theory; Under the condition that the temperature remains unchanged, the leakage pressure difference increases with the increase of pressure, and the variation range is larger than the theoretical value. When the temperature is in the range of 10-40 ℃ and the pressure is in the range of 0.445-1.3 MPa, the average error between the calculated value of the model and the experimental data is 0.0378 MPa, the maximum deviation is 0.044474 MPa, and the minimum deviation is 0.020686 MPa. (4) Comparing the data obtained from the leakage pressure drop calculation model established according to pressure and temperature with the test data, the coefficient of determination can reach 0.9947, and the root mean square error can reach 0.0007075. 124 References [1] Huang Tengfei, Chen Qiuling. 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