2020 Vol. 35, No. 5

Cover
  Previous Issue | Next Issue 
Display Method:
Analysis on mechanism of several piezoelectric networks for vibration reduction of bladed disks
LI Lin, ZHANG Fengling, FAN Yu
2020, 35(5): 897-908. doi: 10.13224/j.cnki.jasp.2020.05.001
Abstract PDF(6263KB) icon824 icon694
Abstract:
The mechanisms of piezoelectric networks were further analyzed for the vibration reduction of cyclic periodic structures such as bladed disks. To illustrate how the energy dissipation and energy balance mechanisms affect the reduction of vibration, numerical studies were conducted based on a lumped parameter model to compare the performance of shunt circuits, parallel network and series network. The best damping performance of such three circuits were compared in both tuned and mistuned cases with varied mistune strength. This illustrated the effects of the energy dissipation. The resistance was introduced to the acyclic network to illustrate the combined action of energy balance and energy dissipation. The qualitative suggestions on the choice of blades to construct an acyclic network was given as well. Results showed that interconnecting all blades to a global piezoelectric network cannot increase the damping performance. The optimal networks were found with only few blades included and without any electric impedance, and this illustrated the effects of energy balance. Vibration reduction can be achieved by only interconnecting few blades (2 or 4 of the overall 24 blades) into the network without any electric components.
Subsonic airflow load of rotating blades excited by subsonic flow
LIU Gen, CHEN Gongfa, XI An
2020, 35(5): 909-917. doi: 10.13224/j.cnki.jasp.2020.05.002
Abstract PDF(2519KB) icon630 icon571
Abstract:
The nonlinear coupled vibration response of the compressor blade under subsonic flow and the condition of 1∶2 internal resonance was studied. The transverse aerodynamic loads of three-dimensional compressor blades were obtained by the vortex lattice method (VL). The mode functions of the first torsional mode and the second bending mode of the rotating blade were obtained by the Chebyshev-Ritz method and the first three frequencies were compared with the finite element results. By using Galerkin method, the partial differential equations of the system were truncated, and the two-degree-of-freedom ordinary differential equations of the torsional mode and the bending mode were obtained. By solving the equations with linear coupling stiffness term, two possible solutions were obtained and the stability analysis was investigated. Through analysis of the energy transfer between these two modes of the system, the force amplitude curve of the torsional mode and the bending mode of the system was calculated when the tuning parameter was σ=0, σ1≠0 and the tuning parameter was σ=0, σ1=0. The saturation behavior and the phenomenon of energy transfer between the modal amplitudes were analyzed. When the external excitation tuning parameter was σ1=0, the jump phenomenon of the torsional mode amplitude disappeared. At the same time, the influences of different parameters on force frequency and amplitude frequency characteristics were analyzed.
Approach to early crack diagnosis of turbine blade based on EEMD energy entropy fusion of three-dimensional tip clearance
ZHANG Yingjie, ZHANG Xiaodong, LIU Hongcheng
2020, 35(5): 918-927. doi: 10.13224/j.cnki.jasp.2020.05.003
Abstract PDF(4022KB) icon691 icon569
Abstract:
Considering that the early crack signal of aero-engine turbine blade is weak and difficult to identify, a diagnosis method was proposed based on ensemble empirical modal decomposition (EEDM) energy entropy fusion of three-dimensional tip clearance. Three-dimensional tip clearance signals of turbine blade were collected and decomposed by using the EEMD to obtain corresponding three-dimensional intrinsic mode functions (IMFs) and calculate the EEMD entropy value of each dimensional signal in order to form different high-dimensional vector sets representing the crack fault. Several stacked autoencoders (SAE) were constructed to learn the high-level features from each high-dimensional vector set and further extract the in-depth feature expression acquired by each SAE. The support vector machine (SVM) algorithm and genetic algorithm (GA) were used to fuse these different high-level features in order to confirm adequately the early crack fault of turbine blades. Results show that the proposed method can fully dig out characteristic information of the early crack, and effectively improve the diagnosis accuracy, yielding an average accuracy of 98.415%, and its standard deviation is only 0.697%, showing its good stability, adaptivity and generalization ability.
Electric field and flow field of LPES surface strengthening of titanium alloy gear
CHEN Feifei, LU Wenzhuang, CHEN Meng
2020, 35(5): 928-937. doi: 10.13224/j.cnki.jasp.2020.05.004
Abstract PDF(5727KB) icon557 icon518
Abstract:
For the problem of forming stable arc discharge on the complex surface of the TC4 titanium alloy gears treated by liquid plasma electrolytic saturation (LPES), a simulation model of the gear surface strengthening system was established, the electric field and flow field were simulated based on simulation analysis and experimental verification methods. The discharge mechanism on the complex surface of the gear was determined. The effects of electrode system parameters and inlet velocity on the formation of the strengthening layer were studied. Results indicated that the fundamental reason for the difficulty of effective discharge on the gear surface was attributable to the uneven electric field. The uniformity of the electric field and the strengthening layer were better when the meshing anode was used. Too small electrode distance was likely to cause short circuit of strengthening system, and too large electrode distance could reduce uniformity and thickness of strengthening layer. Appropriate electrolyte flow rate is important for both the stability of the discharge and the thickness of the strengthening layer. Compared with the untreated substrate, the surface wear resistance of the strengthened titanium alloy gear has been significantly improved.
Continuous scanning laser vibration test method for ODS of thin-walled cylindrical structure
ZHANG Gong, ZANG Chaoping, LI Fan
2020, 35(5): 938-943. doi: 10.13224/j.cnki.jasp.2020.05.005
Abstract PDF(3970KB) icon596 icon505
Abstract:
A continuous scanning laser Doppler vibration test method for operational deflection shape (ODS) of the thin-walled cylindrical outer surface was proposed and applied to vibration test of a cylinder. The rotating platform and motor control were introduced into the laser continuous scanning, and a motor control algorithm matching the laser continuous scan path was developed. The continuous scanning laser vibration test was applied to cylinder structure. And the cylinder laser continuous scanning test was performed on a cylinder structure and the first five orders mode within 500 Hz were obtained. The correlation with the results from the commercial laser discrete scanning modal test was basically above 0.96, demonstrating the feasibility and accuracy of cylinder laser continuous scanning laser Doppler vibration test. The cylinder continuous scanning laser Doppler vibration test, with advantage of high spatial resolution, efficient and effective test, shows certain guiding significance and practical value for further application in actual structure.
Numerical investigation of influence of two-dimensional convergent and divergent nozzle’s design parameters on infrared characteristics
SHI Xiaojuan, JI Honghu
2020, 35(5): 944-955. doi: 10.13224/j.cnki.jasp.2020.05.006
Abstract PDF(4493KB) icon866 icon596
Abstract:
The computational cases of infrared radiation (IR) characteristics of exhaust system were designed using the orthogonal experiment design method. The influences of geometric parameters on IR characteristics of two-dimensional exhaust system were investigated. The geometric parameters studied included throat width to height ratio, throat radius ratio, convergent half angle and divergent half angle of two-dimensional convergent and divergent (2D-CD) nozzle. The sensitivity analysis of the four geometric parameters was performed. Results showed that the divergent half angle was the widest parameter that influenced the spatial range of IR characteristics of 2D exhaust system. The convergent half angle mainly influenced IR characteristics within the range of 10°-30° in the tail direction. The throat width to height ratio mainly influenced the IR characteristics of 0° in the positive tail direction and 90° in the lateral direction. The throat radius ratio had little influence on the IR characteristics. The main influence parameters of IR characteristics in different directions of 2D exhaust system were different. The most important influence parameter in the direction of 0° was throat width to height ratio. The most important influence parameters in the direction of 90° were divergent half angle and throat width to height ratio.
Liquid methane subcooling and filling process using liquid nitrogen as cold source
CHEN Qiang, SUN Qingguo, WANG Tianxiang
2020, 35(5): 956-962. doi: 10.13224/j.cnki.jasp.2020.05.007
Abstract PDF(1473KB) icon788 icon534
Abstract:
In response to the demand of commercial rocket companies for liquid methane subcooling,methane filling systems were designed with liquid nitrogen used as the cold source. Corresponding theoretical calculations under different methane filling flow rates and different liquid nitrogen pressures were also carried out. Referring to the existing liquid oxygen and kerosene filling system,two different control strategies for methane subcooling and filling system were proposed to prevent liquid methane from condensing due to liquid nitrogen. Comparisons between the two systems were made. Six different processes realized by the two systems were introduced and analyzed. Resut showed that, the filling system based on back pressure control was more reliable than that based on liquid level control. At the same time,the former could realize online real-time filling process,because it could ensure that the liquid nitrogen temperature was always higher than the methane freezing point by controlling the liquid nitrogen pressure in the heat exchanger. The heat exchange area of the methane subcooler was proportional to the methane flow rate and the nitrogen pressure. In the specific engineer implementation,the appropriate flow rate and liquid nitrogen pressure should be selected in order to reduce the subcooler size and equipment manufacturing costs.
Numerical simulation of effects of partial nozzle closure on uniformity of parameters in pre-swirl air supply system
LEI Zhao, LIU Gaowen, GU Wei
2020, 35(5): 963-972. doi: 10.13224/j.cnki.jasp.2020.05.008
Abstract PDF(7375KB) icon500 icon467
Abstract:
In order to study the influence of the partial nozzle closure on the air supply mass flow rate, air supply temperature and circumferential uniformity of the air supply parameters of the pre-swirl air supply system, the steady-state method with frozen rotor approach was used to simulate the 180° rotating disk cavity model, and the time-space characteristics of transient problems were approximated by changing the rotor phase in the steady-state calculations. Results showed that: at the design point condition(system pressure ratio of 1.32 and rotating Mach number of 0.678), when the flow area of nozzle was closed by 14.3%, the total bleed air flow and total air supply flow decreased by 10.9% and 9.9%, respectively. The amplitude of fluctuation of the flow rate of a single supply hole increased from 1.1% to 5.4%. The relative total temperature of supply air decreased about 1 K, and the amplitude of fluctuation increased from 0.5 K to 1.5 K.
Film cooling enhancement by using upstream sand-dune-shaped ramp
ZHANG Shengchang, ZHANG Jingzhou, TAN Xiaoming
2020, 35(5): 973-982. doi: 10.13224/j.cnki.jasp.2020.05.009
Abstract PDF(7349KB) icon593 icon539
Abstract:
Single-row film holes were drilled on flat plates, and experimental tests were performed to investigate the cylindrical-hole (CH) film cooling in the presence of upstream sand-dune-shaped ramp (SDR) under four typical blowing ratios of 0.5, 1.0, 1.5 and 2.0 using infrared thermometry method. A straight-wedge-shaped ramp (SWR) was adopted for the comparison. At the same time, numerical simulations were also performed to illustrate different roles of respective upstream ramps on the film cooling enhancement. Results showed that the presence of the upstream sand-dune-shaped ramp helped to generate an additional pair of anti-kidney vortices. As a consequence, the SDR provided a more favorable film cooling enhancement than the SWR. Under a small blowing ratio of 0.5, the area-averaged adiabatic film cooling effectiveness in a specific zone (within 15 times of the hole diameter downstream of the film hole) increased about 26% by SWR and 75% by SDR, with respect to the baseline cylindrical-hole situation. Under a high blowing ratio of 1.5, the area-averaged adiabatic film cooling effectiveness could be increased up to 100% and 150%, respectively, by using SWR and SDR.
Influence of slit type receiver holes on radial pre-swirl system
ZHANG Kai, WANG Suofang, HOU Xiaoting
2020, 35(5): 983-991. doi: 10.13224/j.cnki.jasp.2020.05.010
Abstract PDF(3926KB) icon706 icon451
Abstract:
In order to improve the temperature drop of radial pre-swirl system and reduce the flow loss of the system, numerical simulation was carried out to compare the characteristics of temperature reduction and flow losses of different aspect ratio slits with traditional straight hole type receiver holes. Results indicated that the receiver hole effective flow area increased with the slit aspect ratio increase within the range of 1-10, the flow velocity of the nozzle outlet and the dimensionless mass flow of the system also increased; when the rotational Reynolds number was bigger than 2.6×106, the temperature drop of the system increased with the increase of slit aspect ratio, the total pressure loss increased at first and then became stable gradually. The slit-type receiver holes with aspect ratio of 6-10 had much higher temperature drop and higher pressure loss than traditional receiver holes. When rotational Reynolds number was 7.9×106 and the slit type receiver holes aspect ratio was 10, the temperature drop coefficient increased by 36.7% and total pressure loss coefficient increased by 2.2% compared with the traditional straight hole receiver holes.
Variable angle of attack start experiment of 2D curved compression inlet
ZHU Wei, HUA Zhengxu, WANG Xiao
2020, 35(5): 992-999. doi: 10.13224/j.cnki.jasp.2020.05.011
Abstract PDF(4313KB) icon727 icon592
Abstract:
The reverse design method of curved compression inlet with controllable internal and external compression surfaces was studied, the numerical simulation and experimental study of the designed 2D curved compression inlet starting with varying angle of attack at different Mach numbers were carried out, and the hysteresis loop of the inlet starting angle of attack was obtained. Simulation and experiment indicated that unstarting/self-starting angle of attack, the outflow field and pressure distribution coincided well, and the experiment results also showed that curved compression inlet had high comprehensive aerodynamic characteristics; at design points Ma=4, α=3° back pressure resistance ability was more than 70 times of inflow pressure, total pressure recovery coefficient was above 0.5.
Numerical study on the influence of aero-engine intake and exhaust system on aerodynamic characteristics of aircraft
GAO Xiang, LI Mi, WANG Dingqi
2020, 35(5): 1000-1008. doi: 10.13224/j.cnki.jasp.2020.05.012
Abstract PDF(4490KB) icon811 icon629
Abstract:
In order to analyze the aerodynamic characteristics between aero-engine and aircraft, and to accurately determine the lift-drag characteristics of aircraft under practical use condition, numerical calculation was conducted for a half aircraft model with powerplant. Then the numeical calculation method of three-dimensional flow field was verified with wind-tunnel test data, and the rules of the spillage drag and exhaust interference drag were summarized. Results suggest that: the variation of aero-engine settings has significant influences on the lift-drag characteristics of aircraft. The spillage drag component in lift and drag direction separately increases and decreases with the increase of capture area ratio. The larger difference between real operating condion and reference conditon means the larger absolute value of interference drag components.
Development of liquid nitrogen supplying system of 0.3 m cryogenic wind tunnel
ZHANG Wei, GAO Rong, ZHANG Shuangxi
2020, 35(5): 1009-1017. doi: 10.13224/j.cnki.jasp.2020.05.013
Abstract PDF(2348KB) icon516 icon385
Abstract:
A numerical model was built to investigate the dynamic performance of the liquid nitrogen supplying system in the 0.3 m cryogenic wind tunnel. Based on one-dimensional thermal fluid analysis, the model was used to analyze heat leakage, level of the accumulator, two-phase flow and injection pressure. Combining the numerical model with control strategy and experiments, the dynamic pressure analysis for the injection rake was achieved. It showed that the relative error between numerical results and experimental data was below 10%. During experimental validation, the interference of the four regulating valves was avoided with universalization of the nominal working pressure of injection nozzles and convergence of pipes after these valves. The second recirculation pipe above the injection rake was used to eliminate the two-phase flow phenomenon of the terminal of the system, helping to make the control accuracy reach 1.1%, and adjust time to 23 s. With the numerical studies and reconstruction of the pipes and nozzles, the liquid nitrogen supplying system is able to meet the requirement of the total temperature control of the wind tunnel.
Numerical simulation of multi-rotor aircraft in vortex ring state
WANG Junjie, CHEN Renliang, WANG Zhijin
2020, 35(5): 1018-1028. doi: 10.13224/j.cnki.jasp.2020.05.014
Abstract PDF(6495KB) icon574 icon474
Abstract:
A dynamic grid technology based on unstructured grid was used to simulate the aerodynamic characteristics of multi-rotor aircraft in the descent state, and experimental verification was performed. This method was used to simulate the flowfield of the aircraft in the vertical descent state and the 30° oblique descent state. The aerodynamic characteristics of the multi-rotor aircraft and the law of the flowfield in the slipstream region were obtained in this state, and the variations of force and power were also obtained. The study found that the multi-rotor aircraft would enter the vortex ring state in both vertical descent and 30° oblique descent. When the vertical descent speed dropped to 4 m/s, the multi-rotor aircraft was already in the vortex ring state, the loss of the thrust reached 15%, the rotor power increased first and then decreased with the increase of vertical descent speed, the thrust and power of different rotor of the aircraft were not consistent. When the 30° oblique descent speed reached 4-6 m/s, the multi-rotor aircraft was in vortex ring state. This conclusion can provide a reference for the safe flight of multi-rotor drones.
Numerical simulation of high bypass ratio turbofan engine with total pressure inlet distortion
GUO Jin, HU Jun, TU Baofeng
2020, 35(5): 1029-1041. doi: 10.13224/j.cnki.jasp.2020.05.015
Abstract PDF(7231KB) icon886 icon482
Abstract:
Based on the concept of numerical zooming and taking a high bypass ratio turbofan engine as the research carrier, a mixed-dimension computational model to investigate the effect of complex inlet distortion on the characteristics of flow field in aero engines was preliminarily established by integrating a three-dimensional body force model and a two-dimensional multiple segment parallel engine model. The mixed-dimension model was utilized to analyze the characteristics of flow field in the engine under different forms of total pressure distortion, including steady circumferential total pressure distortion and flat baffle total pressure distortion. Results revealed that even if the total circumferential pressure distortion of the square wave at the inlet was simple, there were significant differences in the distortion flow field characteristics at the core and bypass inlet after the action of the fan rotor with high bypass ratio. The combined total pressure/total temperature distortion formed at the core inlet was attenuated under different degrees in the four-stage booster compressor. A certain degree of swirl was induced by the circumferential static pressure gradient near the hub region of the fan rotor inlet under the flat baffle total pressure distortion. Thus, the low pressure area was formed near the hub of the fan rotor outlet.
Compression performance of double-sided composite impeller with micro gas turbine
ZHANG Cheng, WANG Yun, WANG Ke
2020, 35(5): 1042-1050. doi: 10.13224/j.cnki.jasp.2020.05.016
Abstract PDF(5793KB) icon543 icon420
Abstract:
In order to achieve the core engine with high performance parameters and high-tech equipment, based on the ideas of structural fusion and thermal process fusion, the core engine of traditional micro-turbine was integrated through innovation. Based on the 3D printing design and manufacturing technology foundation, a double-sided composite impeller structure was designed, with a radial connection of a double-sided conventional impeller and an axial-flow turbine, making it possible to become a type of high-efficiency impeller with great potential in the future. Specifically, the principle, structural scheme and expected performance of the micro gas turbine were analyzed. Numerical investigation of aerodynamic compression performance of a double-sided composite impeller and backward pipe heat transfer characteristics was primarily studied. Results show that compared with the conventional impeller, the aerodynamic compression performance of the double-sided composite impeller can meet the expectation perfectly. The total pressure ratio, flow rate and isentropic efficiency have been greatly improved; the recovery of 4.4 K exhaust gas temperature in the rear intake pipe can improve the thermal efficiency. It has laid the foundation for the development of gas turbines with high aerodynamic performance and high cycle parameters.
Non-axisymmetric endwall modeling for large meridional expansion turbines based on pressure field distribution
HUANG Jingwei, MENG Fusheng, SONG Yikang
2020, 35(5): 1051-1065. doi: 10.13224/j.cnki.jasp.2020.05.017
Abstract PDF(11808KB) icon601 icon402
Abstract:
To improve large meridional expansion turbine side area of pneumatic and heat transfer performance, based on the large meridional expansion turbine upper wall static pressure distribution in detail, non-axisymmetric endwall modelling technology was employed for eight kinds of asymmetric design for a 1.5 magnitude large meridional expansion level 2 of a turbine upper wall, by combining the Bezier curve with a sine curve of trigonometric function; and the SST（shear stress transfer） turbulence model was used to solve the RANS（Reynolds-averaged Navier-Stokes equations） equations of end wall before and after the modelling of the flow and heat transfer characteristics research. Results showed that the non-axisymmetric design of the upper endwall of a large meridional expansion turbine can effectively improve the distribution of transverse pressure difference in the blade passage at the upper end of the turbine. The total pressure loss at the outlet can be reduced by bulking the upper endwall pressure surface in the channel. When the bulking amplitude is 5% of the S2 blade height, the total pressure loss at the outlet can be reduced by 1.1% at most. The heat load of the casing and blade can be reduced by hollow modeling on the suction and pressure surfaces of the upper end wall. When the sag amplitude is 5% of the blade height of S2, the thermal load of the casing and blade can be reduced by about 3.1% and 2.8% respectively at most.
Temperature field of double helical star gear transmission system in mixed lubrication condition
LIN Tengjiao, HUANG He, PENG Jiantao
2020, 35(5): 1066-1080. doi: 10.13224/j.cnki.jasp.2020.05.018
Abstract PDF(12551KB) icon569 icon392
Abstract:
For double helical star gear transmission system, the proportion of load carried by film and the friction coefficient at different meshing positions on tooth surface with different roughness were calculated based on thermoelastohydrodynamic lubrication theory and asperity contacting analysis. In combination with the calculation of contact load and slip velocity, the distribution of heat flux on tooth surface was analyzed. By simulating the flow field of gear transmission system in spray lubrication, the oil distribution and wall heat transfer coefficient of gears’ surfaces were determined. Then steady-state thermal finite element model of gear transmission system was built based on the results of flow field simulation and mixed thermoelastohydrodynamic analysis, and temperature distribution of gears’ surfaces was analyzed through simulation. Results showed that thicker central oil film got higher proportion of load carried by film. The comprehensive friction coefficient was affected by geometric parameters and load, and increased at first and then decreased from pitch point to addendum and dedendum region for internal and external gears. The sun gear got higher temperature than others with high meshing frequency and poorer heat dissipation, as the high temperature zone was located in addendum and dedendum, and the temperature rose obviously as roughness increased.
Research on tooth surface design and undercutting of non-orthogonal arc tooth face-gears
CHEN Yong, FENG Zhanrong, SHENG Wei
2020, 35(5): 1081-1088. doi: 10.13224/j.cnki.jasp.2020.05.019
Abstract PDF(2379KB) icon561 icon385
Abstract:
The tooth surface equation of non-orthogonal arc tooth face-gear was derived according to the principle of face-gear meshing. The undercut phenomenon of this type of face-gear was studied by combining Matlab mathematical model with undercut theory, and the maximum internal diameter of face-gear without undercut was calculated. Catia simulation hobbing was used to verify the accuracy of the calculation. A new type of non-orthogonal face-gear was proposed. The undercut phenomenon of this kind of face-gear was studied through theoretical derivation and simulation. Based on this, the factors affecting the internal diameter of non-orthogonal arc tooth face-gears were explored. Results showed that under the same parameters, when the position parameter increased, the height and inner diameter of the involute section of the tool gradually reduced. When the radius of the tool increased, the inner diameter gradually reduced, and the height of the involute section of the tool gradually increased.
Civil turboshaft engine induction system icing test
SONG Jianyu, WU Jingfeng, QIU Changbo
2020, 35(5): 1089-1098. doi: 10.13224/j.cnki.jasp.2020.05.020
Abstract PDF(2318KB) icon864 icon426
Abstract:
Focusing on the content of China Civil Aviation Regulations CCAR-33R2 article 33.68, a test method for turboshaft engine complying with airworthiness regulation requirement was provided, including icing critical point analysis, icing certification test points determination, engine icing certification test. In combination with the turboshaft engine operating envelope, critical point analysis was conducted to determine the icing certification test points. Several icing calculation points were selected in the icing envelope, and icing positions and amounts were calculated for each point. The calculation results show that the area where the temperature is close to 0 ℃ and the altitude is low is the zone where the turboshaft engine has a significant ice amount. During the icing test, the temperature points at which ice formation just occurred and the amount of icing was the largest were found in the temperature range of -4 ℃ to -1 ℃. The test results show that the temperature point with the largest amount of icing is the most severe icing test point.
Flammability and airworthiness compliance method of fuel tank for transport aircraft
ZHANG Ruihua, LIU Weihua, LIU Chunyang
2020, 35(5): 1099-1108. doi: 10.13224/j.cnki.jasp.2020.05.021
Abstract PDF(3238KB) icon716 icon396
Abstract:
Based on the airworthiness certification needs of domestic transport aircraft, the changing history, the connotation and index requirements of CCAR/FAR25.981 were systematically analyzed. From the perspective of the model applicant, a preliminary discussion on the conformity methods to be adopted in the process of airworthiness certification was conducted. Meanwhile, the flammability indexes and conformity verification methods of different types of fuel tanks were summarized. Subsequently, the fuel tank flammability assessment application issued by Federal Aviation Administration（FAA） was studied. Research shows that: (1) the revision of airworthiness regulations is the result of the development of fuel tank safety technology and knowledge level, and the airworthiness regulations must be closely combined with the current mainstream technology level; (2) different types of fuel tanks allow different levels of fleet average flammability exposure, among which fuselage fuel tank is the focus of airworthiness certification; (3) the difficulty of the average flammability exposure time of the computer team lies in the accurate acquisition of the balance temperature difference and time constant, which can be solved through establishment of fuel tank thermal model and genetic algorithm tracking.
Control algorithms for adjustable flow gas generator of ducted ramjet
ZHOU Jingliang, CHEN Xiong, CHAI Jinbao
2020, 35(5): 1109-1120. doi: 10.13224/j.cnki.jasp.2020.05.022
Abstract PDF(3510KB) icon690 icon422
Abstract:
The gas generator system with adjustable flow of ducted ramjet has strong time-varying and non-linearity. Anti-regulation of gas flow exists in the initial stage of regulation. And the in the gas generator system with adjustable flow of ducted ramjet has strong time-varying and non-linearity attributes. Anti-regulation of gas flow exists in the initial stage of regulation. And the incomplete combustion of propellant is easily adhered to throat. These factors will have a negative impact on the regulation performance. In order to solve this problem, the linear active disturbance rejection controller (LADRC) was designed. Simulation results showed that: compared with the proportion-integration-differentiation (PID) controller, the LADRC had better response speed, accuracy, flow anti-regulation suppression ability and anti-interference ability. The response time under low and high pressure conditions was less than 1.5 s, the overshoot was less than 1.5%, and the flow anti-regulation was reduced by 3-4 times. The reaction time to interference was about 0.4 s, and the deviation value of interference was only 0.25 MPa, thus significantly improving the performance of gas generator.

Copyright © 《Journal of Aerospace Power》 All Rights Reserved.

Supported by: Beijing Renhe Information Technology Co., Ltd.