2013 Vol. 28, No. 11

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Design analysis of active cooling composite combustion chamber with thin wall
ZHANG Jun-feng, MU Dan, BIAN Xiang-de
2013, 28(11): 2401-2407.
Abstract PDF(1068KB) icon2359 icon1086
Abstract:
Using the proposed fluid solid coupling heat transfer model, numerical simulation was carried out for the transient heat transfer properties of active cooling combustion chambers with thin wall with different geometric sizes of cooling channels. The distribution and evolution of transient temperature field of active cooling combustion chambers were given. Finite element method was adopted to calculate the thermal stress and strain of combustion chamber. The influence laws of geometric parameters of cooling channels and inner volume flow rate of kerosene on the highest temperature and thermal stress of the thin wall of combustion chamber were explored. The results show that, while bringing the kerosene cooling effect into full play, if the cooling channel is closer to the inner wall of the combustion chamber, the larger kerosene volume flow rate is needed. More attention should be paid to the material properties at 10s when the thermal stress of the combustion chamber structure reaches peak value.
Effects of combustion heating vitiated air on kerosene-fueled scramjet performance
CHEN Liang, SONG Wen-yan, LUO Fei-teng, LIU Hao, LI Jian-ping
2013, 28(11): 2408-2418.
Abstract PDF(1392KB) icon1458 icon991
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For the problem of test media vitiation associated with scramjet ground test facility, the effects of combustion heating vitiated air on kerosene-fueled scramjet performance were investigated with validated numerical approach. Under the simulating condition of flight Mach 6.0, the flow-field and performance of the scramjet were numerically calculated with clean free airstream and vitiated free airstream, respectively. Several matched parameter schemes for vitiated free airstream relative to clean air were considered. It indicates that among the pressure-interrelated parameters, the least discrepancy resulting from vitiation effects is found when the static pressure is matched, while the most discrepancy is found when the total pressure is matched; among the temperature-interrelated parameters, the least discrepancy resulting from vitiation effects is found when the static temperature is matched, while the most discrepancy is found when the total temperature is matched. As for the vitiation effects of combustion heating vitiated air, selection of pressure-interrelated parameters to be matched is more significant than selection of temperature-interrelated parameters. The present efforts can provide theoretical basis for understanding the vitiation effects on the scramjet and determining the simulation rules of ground test with vitiated free airstream.
A spongy icing model for aircraft icing and application
LI Xin, BAI Jun-qiang, WANG Kun
2013, 28(11): 2419-2429.
Abstract PDF(1422KB) icon1424 icon1119
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An Eulerian method to simulate aircraft icing was developed based on two-phase flow theory, and the water collection efficiency and impingement limits were solved based on the velocity distribution of air flow. Results show that Eulerian method performs better on water collection efficiency and impingement limit than Lagrangian method, especially under large median volumetric diameter conditions. The predicted ice shape and surface temperature were compared with experimental results, the thickness error of the cylinder ice shape was less than 15.0% and the computational results were in good agreement with the experiment data, showing that the icing model and two-phase flow simulation are feasible and effective.
Numerical simulation and experiment on air-assisted direct injection injector dynamic spray field
CHENG Qiang, ZHANG Zhen-dong, XIE Nai-liu
2013, 28(11): 2430-2439.
Abstract PDF(1301KB) icon1557 icon1010
Abstract:
In order to study the spray form and development law of the air-assisted direct injection (AADI) injector of small aircraft engines,numerical simulation and high-speed photography technology were used to study the dynamic spray field. The physics model of cone valve motion was defined as the moving boundary conditions of numerical calculation. The spray velocity distribution, static and dynamic pressure distribution and spatial distribution atomization particles at different times of AADI injector were analyzed by dynamic grid. The spray pattern, atomization and penetration were compared by experiments and simulations in 3ms every 0.2ms. Results show that CFD simulation technology was used to analyze velocity distribution, pressure distribution, spray pattern and other parameters of the dynamic spray field of AADI injector,helping to reveal the development rule of the spray; moreover, through quantitative comparison analysis of the particle sizes and penetration distance, the accuracy of simulation calculation was shown. The deviation of numerical simulation and experimental results is less than 5%, meeting the requirements of engineering applications.
Effect of film cooling on flow and heat transfer of flat tip in transonic turbine cascade
ZHOU Kai, ZHOU Chao, ZHONG Fang-pan
2013, 28(11): 2440-2447.
Abstract PDF(1052KB) icon1415 icon1009
Abstract:
Computational fluid dynamics (CFD) was used to investigate the aerothermal performance of tip leakage flow of a flat tip in a transonic high pressure turbine cascade. The effects of tip film cooling were considered. For the flat tip without tip cooling, shock waves were reflected between the endwall and the blade tip within the tip gap. As a result, the surface heat transfer coefficient is distributed as stripe pattern on the tip surface from blade midchord to the trailing edge. The injection of the coolant has a significant effect on the flow patterns within the tip gap. The coolant reduces the velocity of the flow within the tip gap. As a result, oblique shock waves are no longer obviously observed. The coolant covers the areas downstream the cooling holes. When increasing the inlet stagnation total pressure ratio of the coolant to the main flow from 0.7 to 1.0, the average film cooling effectiveness on the tip varies from 18.7% to 11.5%. Compared to the uncooled flat tip, at the inlet stagnation total pressure ratio of 0.9, the average surface heat transfer coefficient on the cooled flat tip increases by 16.9%, and the heat flux of the tip reduces by 8.7%.
Flow field and film cooling characteristics in supersonic turbine cascade
CHEN Si-jie, SHAN Yong, ZHANG Jing-zhou, TAN Xiao-ming, FEI Wei-wei
2013, 28(11): 2448-2454.
Abstract PDF(1130KB) icon1359 icon971
Abstract:
The shear strain transport(SST) k-ω two-equation turbulence model was employed to numerically simulate the film cooling characteristics in the supersonic turbine cascade channel.The flow characteristics in the cascade channel and the change law of the film cooling efficiency were obtained at different gas film hole angles and blow ratios.The film jet near shock incident point can complement momentum to the boundary layer of separation zone,overcome the adverse pressure gradient and effectively improve the local overheating caused by shock wave.In subsonic flow state,the film incidence angle's impact on the efficiency of cooling can be embodied at larger blow ratio;on the contrary,in supersonic flow state,the film cooling efficiency is almost independent of the incidence angle,showing that the penetrating power of subsonic film to the supersonic mainstream is weaker than that to the subsonic mainstream;in the supersonic mainstream state,the film cooling efficiency of the shock incident location is higher than that of the downstream,which is mainly related to local turbulence intensity of the gas film.
LES of direct detonation induced by incident circular shock wave focusing
BAO Xing-dong, LI Zhi-qiang, TUO Huan, DONG He
2013, 28(11): 2455-2461.
Abstract PDF(1077KB) icon1468 icon1112
Abstract:
Based on large eddy simulation(LES), an element reaction model was used to investigate direct detonation induced by incident circular shock wave focusing of hydrogen-air combustible mixture by detailed numerical simulation. Research results show that, under the condition of inlet Mach number of 2.5, the high energy region by incident circular shock wave focusing may achieve direct detonation for detonation wave formation in combustible gas, and fuels can react efficiently and completely. Vertical circular shock wave can't induce the process of detonation. So, incident circular injection is more useful to direct detonation by fuel mixture focusing.
Atomization characteristics of fuel injector and cavity-based strut flame stabilizer under close-range matching condition
LUO Lian-jun, LIU Yu-ying, ZHANG Wen-long, JI He-ming
2013, 28(11): 2462-2467.
Abstract PDF(880KB) icon1388 icon1050
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Malvern laser particle analyzer was used to study the atomization characteristics along the axial direction of fuel injector and cavity-based strut flame stabilizer under close-range matching condition, with stream Mach number of 0.16 to 0.24, spray pressure drop of 0.30MPa to 0.90MPa, distance of fuel injector and stabilizer up to 31.5mm and spray in the direction of stream flow with water and kerosene. The results show that the Sauter mean diameter(SMD) of liquid drop decreases with increasing stream Mach number and increasing spary pressure drop. But the SMD of liquid drop was not sensitive to spray pressure drop in recirculation zone and to Mach number in main stream zone at the far-field downstream position of cavity-based strut flame stabilizer. Furthermore, the SMD of liquid drop decreases gradually along the axial direction, and decreases gradually in recirculation zone but increased gradually in main stream zone along the radical direction.
Analysis on flow and infrared radiation characteristics of double S-nozzle
ZHANG Ye-chuan, WANG Zhan-xue, SHI Jing-wei, FANG Li, KONG De-ying
2013, 28(11): 2468-2474.
Abstract PDF(979KB) icon1449 icon971
Abstract:
Based on partition control technology and CFD numerical simulation,the easily controllable design methods of double S-nozzle type surface were developed,and the flow characteristics of double S-nozzle were simulated.With message passing interface (MPI) parallel algorithm and discrete transfer method,the software of infrared radiation characteristics was programmed.The infrared radiation characteristics of double S-nozzle were computed by the software.The infrared radiation characteristics were compared with those of axisymmetric convergent nozzle with the same inlet and outlet areas.The results show that the infrared radiation intensity of wide detection surface of double S-nozzle is less than that of the narrow detection surface,with the biggest margin up to 80%.The infrared radiation intensity on each probing direction is lower than that of axisymmetric convergent nozzle,especially on the probing direction between 30° and 40° in the wide detection surfaces,and the infrared radiation intensity of double S-nozzle is lower 30% than that of axisymmetric convergent nozzle.
Static aeroelastic problems of transonic fan blades
ZHENG Yun, WANG Biao, YANG Hui
2013, 28(11): 2475-2482.
Abstract PDF(1138KB) icon1743 icon1059
Abstract:
A time domain fluid-solid interaction numerical calculation method was applied to study the static aeroelastic problems of transonic fan blades under aerodynamic and centrifugal forces. The blade deformation rules and its effects on aerodynamic performance were analyzed under various working conditions. Static aeroelastic simulation of the NASA rotor 67 indicates that the aerodynamic contribution to the maximum blade deformation accounts for 13.07% of the total deformation, and the passage shockwave position and strength are altered due to the blade deformation. The static aeroelastic simulation of a wide-chord hollow transonic fan blades reveals that the effects of blade deformation on the aerodynamic efficiency is 0.15%-0.5%. The aerodynamic contribution to total deformation at leading edge is up to 41% and the aerodynamic characteristic map of this fan is shifted rightwards with the increasing mass flow rate. The overall results show that the nonlinearity of aerodynamic force has significant effects on the static aeroelastic property of transonic fan blades, and the blade un-running design in industrial practice should adopt a fluid-solid interaction method to attain more accurate blade shapes.
Numerical simulation of inter-stage bleeding in highly-loaded multistage axial compressor
SHA Xin-guo, YAN Ming, LIU Zheng-liang
2013, 28(11): 2483-2494.
Abstract PDF(1644KB) icon1429 icon1042
Abstract:
Taking a highly-loaded eight-stage axial compressor as an object of research, the effect of inter-stage bleeding on compressor performance, inner flow-field and inter-stage matching in highly-loaded multistage axial compressor was investigated numerically. The result shows that inter-stage bleeding can significantly improve the compressor's performance. The bleeding results in 1% increase of the inlet mass flow and of 1.5% increase of the highest efficiency. In addition, the bleeding can decrease the pressure and density of air near the bleeding pores. This leads to an increase of mass flow upstream with the largest load position of rotors moving to downstream as well as a decrease of the mass flow downstream with the largest load position of rotors kept steady proximately. Moreover, bleeding contributes to change the working point position of stages in upstream and downstream of the bleeding position and alter the inter-stage matching of compressor. At the same time, bleeding at the trailing edge of stator could diminish thickness of boundary layer and change inlet condition of rotor downstream.
CFD result validation and analysis of a subsonic centrifugal compressor impeller with splitter blades
LI Pei-yuan, GU Chun-wei
2013, 28(11): 2495-2502.
Abstract PDF(1109KB) icon1454 icon967
Abstract:
A subsonic centrifugal compressor impeller with splitter blades of 1.5 pressure ratio was analyzed by CFD software of Numeca using Spalart-Allmaras(S-A) and shear stress transport(SST) models to study the accuracy of numerical simulation results. The measured results of the impeller and verifications of CFD at four sections were presented with respect to the velocity distribution, etc. Results show that the simulation results of S-A and SST models are almost the same, with the difference less than 1%; In general, the numerical simulation agrees well with the experiment, the difference is less than 2% at design point and 6% in off-design condition. The difference of numerical simulation and experiment results of velocity distribution is large in different cross sections. There are relatively big differences about 20% near hub and more than 100% near shroud, which can not truly reflect the flow condition near the shroud.
Effect of slotted blade on performance of high-turning angle compressor cascades
WU Pei-gen, WANG Ru-gen, LUO Kai, GUO Fei-fei
2013, 28(11): 2503-2509.
Abstract PDF(1062KB) icon1389 icon855
Abstract:
A practical method to control the separation by cutting a slot through the pressure surface and the suction surface was proposed. A converged turning slot configuration was designed. The flow performance with different incidences was investigated. The experimental result was used to check the CFD result, so as to acquire the quantitative flow field structure. The structural static analysis was made. The results show that, in the incidence of 4 degree, the application of slot decreases the wake width of cascades by 16.7%, and decreases the peak of total pressure loss coefficient by 6.07%. In the incidence of 6 degree, the application of slot decreases the peak of total pressure loss coefficient by 14.7%. Fluid can flow from the pressure side to the suction side with slot configuration. The injection air increases the velocity of boundary layer, therefore enhancing its ability to resist the flow separation. Consequently it can decrease the total pressure loss, increase the static pressure ratio, and expand the stability range. It is thus necessary to reduce the stress concentration on fore wall of channel.
Measurement of flow field in compressor stator passages
LUO Ju, HU Jun, YAN Wei, ZHANG Chen-kai, YIN Chao
2013, 28(11): 2510-2516.
Abstract PDF(1049KB) icon1367 icon871
Abstract:
In order to study the effect of stator hub gap on performance and flow field of compressor,four "L" type five-hole probes with different lengths and a four-hole probe were designed.The three-dimensional flow field at five sections in the first-stage stator passage of a two-stage axial compressor was measured with those probes,which were driven by displacement mechanism under the maximum flow and near stall conditions.Results show that mixing of main stream with hub leakage flow and tip corner separation are the main causes of total pressure loss in stator passages.There are four main vortexes in stator passage,which are upper/lower passage vortex,tip corner vortex and leakage vortex.
Effect of tip clearance leakage on performance of centimetre-level high subsonic micro axial flow turbine
YU Haibin, DENG Yang, XIA Chen, FU Xin, HUANG Guo-ping
2013, 28(11): 2517-2525.
Abstract PDF(1196KB) icon1419 icon918
Abstract:
The effect of the tip leakage on the flow field structure and turbine performance of a 78.4mm diameter centimetre-level high subsonic micro axial flow turbine of a micro turbine engine(MTE) prototype was analyzed by numerical simulation. Results show that the relative tip clearance size of micro axial turbine is within the range of 3.1%-4.6%, which is higher than that of conventional axial flow turbine. The effect of tip leakage vortex extends towards the mid of the vanes, of which the leakage losses account for 35% of total losses of the turbine stage, showing a significant increase compared to the conventional axial flow turbine. Studies on the impacts of the law of the gap size of the centimetre-level high subsonic micro axial flow turbine have shown that, once the gap size for each increases by 1% of the blade height, the efficiency will decrease up to 1.9%, which is more distinct than the conventional turbine. Finally, an optimum gap size (0.4mm) was determined due to the restrictions of engineering installation (centrifugal deformation, thermal deformation, bearing clearance, machining and assembly errors, etc), and the performance parameter of the impeller was acquired by numerical simulation: total pressure ratio of 2.12, efficiency of 0.87, mass flow of 0.35kg/s.
Experiment on aerodynamic performance of APU air inlet system with perforated plate
WANG Ming-sheng, WANG Hu-shan, LI Qiang, HUANG Guo-ping
2013, 28(11): 2526-2535.
Abstract PDF(1359KB) icon1353 icon884
Abstract:
The aerodynamic performance of a kind of air inlet system with perforated plate used in auxiliary power units (APU) was investigated experimentally. The experimental results show that with the increase of mass flow rate, the outlet total pressure recovery coefficient and total pressure distortion coefficient decrease. The total pressure recovery coefficient decreases slightly in the fixed total mass flow rate case, but decreases linearly in the fixed proportion case. The total pressure distortion is mainly influenced by the imperforate area of the whole perforated plate in the circumferential direction and the flow passage curvature in the radial direction. With the increase of orifice ratio, the outlet total pressure recovery coefficient increases accordingly. The total pressure distortion of power section is mainly influenced radially in different orifice ratios; the distortion of load section is mainly influenced circumferentially in small orifice ratio and radially in large orifice ratio.
Hybrid LES/RANS simulation of transverse sonic injectionin supersonic turbulent boundary layer
CHEN Ti, LIU Wei-dong, SUN Ming-bo, FAN Xiao-qiang, LIANG Jian-han
2013, 28(11): 2536-2542.
Abstract PDF(962KB) icon1646 icon1658
Abstract:
A hybrid large eddy simulation/Reynolds-averaged Navier-Stokes (LES/RANS) method was tested by computing transverse sonic injection in supersonic turbulent boundary layer. The method combined two-equation k-ω SST (shear stress transport) turbulence model and a mixed-scale sub-grid scale model for turbulence closure depending on wall distance and a blending function of local turbulent parameters. The results show that the hybrid method can capture the unsteady large scale structures of the jet/turbulent boundary-layer interaction. Also, it provides better predictions of separation region length, wall static pressure peak value and static pressure distribution in the expansion regions than the RANS method.
Modified axisymmetric basic flowfield for hypersonic inward turning inlet
LI Yong-zhou, ZHANG Kun-yuan, LUO Lei, WANG Lei
2013, 28(11): 2543-2552.
Abstract PDF(1381KB) icon1366 icon855
Abstract:
The leading edge shock wave near the center body,which is too intensive in axisymmetric basic flowfield,was separated into one curved shock and partial isentropic compression wave using the design method of controllable Mach number distribution.With a structure of four shock waves and four regions,the modified basic flowfield could improve compression efficiency obviously.The circular intake inward turning inlets for modified basic flowfield and common basic flowfield of two shock waves and three regions were designed,and also numerically studied to obtain the flowfield characteristics and general performance.The results indicate the modified inlet has similar flowfield characteristics for the basic flowfield.It features high compression ratio and mass flow capture capability for Mach number of 4.0 to 7.0,and the pressure ratio and total pressure recovery coefficient are 17.56 and 0.540,respectively,at the design point.Besides,the leading shock and converged isentropic compression wave attached the cowl lip in turn while the Mach number of incoming flow varied from high to low,increasing the mass capture ratio and decreasing the total pressure loss.Its overall performance is better than common one with 23.6% higher total pressure recovery coefficient at Mach number of 7.0 and 5.7% higher mass flow coefficient at Mach number of 4.0.
Effect of asymmetric ground effect on stabilitiy of tailless aircraft
YANG Mu-qing, MA Dong-li
2013, 28(11): 2553-2560.
Abstract PDF(1190KB) icon1117 icon845
Abstract:
The research focus was put on asymmetric ground effect, especially on the lateral and directional aerodynamic characteristics. Effects of height of wing chord plane to deck, Reynolds number and wind over deck (WOD) were studied. Computational fluid dynamics (CFD) method was used and validated by comparing with the experimental data presented in previous reports. Height of wing chord plane to deck is the most important factor that influences lift, rolling moment and yawing moment. Lateral and directional stabilities are weakened by reducing height of wing chord plane to deck. Lateral stability decreased 2.8% and 5.6% as the height of wing chord plane to deck was reduced from 1.5m to 1.2m and 1.0m, respectively. By increasin g Reynolds number, lift is increased significantly, while yawing moment is little influenced. Magnitudes of both lift and rolling moment are amplified slightly with the increase of WOD.When WOD varied from 0m/s to 15m/s, lift and rolling moment varied only within 1.1% and 3.4%, respectively. Thus the effect of WOD is found to be secondary.
Performance simulation and verification of air-turbo-ramjet
LI Cheng, ZHOU Zheng, TU Qiu-ye, CAI Yuan-hu
2013, 28(11): 2561-2566.
Abstract PDF(899KB) icon1388 icon952
Abstract:
In order to verify the validity of air-turbo-ramjet (ATR) model, modifications were made with reference to public experimental data. ATR throttle performance and transient state performance were simulated by using the modified model. Comparisons between the calculated results and experimental data show no more than 1% errors in the modeling precision at the high corrected rotating speed and no more than 5% errors at the low corrected rotating speed. The increasing errors at the low corrected rotating speed are due to the inaccuracy of gas property at exit of the gas-generator and the burner. Trends of all the parameters obtained from the model agree well with the experimental data above the idle speed. The comparison results demonstrate the high fidelity of this ATR model, while the rationality and reliability of existing ATR model are also demonstrated.
Optimum design method of acceleration and deceleration control schedule for gas turbine engine
SHI Yang, TU Qiu-ye, CAI Yuan-hu, QIU Chao, TAN Zhi-yong
2013, 28(11): 2567-2571.
Abstract PDF(881KB) icon1443 icon1056
Abstract:
An optimum design method of acceleration and deceleration control schedule for gas turbine engine was proposed. Based on the engine transient state performance model, the transient state control schedule was optimized by changing the independent variables describing engine transient state performance of the nonlinear model in terms of the constraints. An example of the optimal acceleration control schedule for a dual axial mixed exhaust turbofan engine with different restrictions during accelaration was designed by using this method. The control schedule was verified by putting back into the engine transient state performance model. Overall relative optimize error is in order of 0.1‰. The results show enough accuracy and easy use of this method.
Numerical simulation of meso-mechanical response for superalloy ZSGH4169
YU Duo-kui, YANG Xiao-guang, ZHANG Ke-shi
2013, 28(11): 2572-2578.
Abstract PDF(1048KB) icon1176 icon881
Abstract:
Based on crystal plasticity constitutive theory, polycrystalline representative volume element (RVE) was used to investigate the cyclic stress/strain response of superalloy ZSGH4169 in meso scale under multiaxial stress state at 650℃. The simulations reveal that ratcheting is significant under biaxial load control, which is consistent with uniaxial stress state commonly conducted in low cycle fatigue tests. The comparison of the two stress states indicate that the residual strain of initial cycle under uniaxial stress state is three times of that under biaxial condition at 1150MPa. Meanwhile, the residual strain, which is about 1.2%, is stable under the biaxial stress, but the uniaxial condition is unstable. Analysis of inhomogeneity for the plastic strain accumulation and stress further shows that the inhomogeneity of the stress and strain will increase with the cycles under both conditions. However,the average stress increases with cycles under uniaxial conditions while it will remain almost constant under biaxial conditions.
Dynamic response analysis and wall thickness optimization of detonation combustor under actual detonation loading
ZHENG Long-xi, CHEN Jing-bin, HUANG Xi-qiao, LU Jie, CHEN Xing-gu
2013, 28(11): 2579-2586.
Abstract PDF(1052KB) icon1253 icon801
Abstract:
According to a detonation combustor with 60mm inner diameter,the finite element model was built,and the actual detonation loading obtained by experiments was loaded.The influences of different factors on equivalent stress of detonation combustor were calculated under multi-cycle working condition,and the optimization of the detonation combustor wall with constant thickness was completed.It is found that the peak equivalent stress at rear section is 20MPa higher than that at head section on average.The temperature has a significant effect on the equivalent strain of detonation combustor,and the maximum equivalent strain at 30Hz is increased by 51.2% if the temperature is considered.Compared with the material and temperature,the wall thickness of detonation combustor has great influence on the equivalent stress.Under the room temperature and wall thickness of 0.95mm,the maximum equivalent strain reaches 200MPa,almost reaching the yield limit (205MPa) of the material.The calculation results by replacing the model material show that materials with the characteristics of higher yield limit,modulus of elasticity and lower density can reduce the equivalent stress of detonation combustor.
Fatigue life prediction model based on critical plane of nickel-based single crystal superalloy
WANG Rong-qiao, JING Fu-lei, HU Dian-yin
2013, 28(11): 2587-2592.
Abstract PDF(1279KB) icon1358 icon979
Abstract:
A model was developed for fatigue life prediction of nickel-based single crystal superalloy based on critical plane and cyclic damage accumulation.The slip plane with the maximum inelastic strain energy density was chosen as the critical plane of nickel-based single crystal superalloy which was subjected to the most serious damage.Based on the results of viscoplastic deformation analysis on slip systems,the relation between the fatigue life and the parameters of the critical plane such as the maximum resolved shear stress,the maximum shear strain rate due to slip,shear strain range due to slip,strain ratio and the tension/compression dwell frequency,was formulated.The life prediction method was validated with the fatigue testing results of DD6 at 760℃.The experiments agree well with the calculations,and almost all of the results fall in the scatter band of 2.
Multi-plane and multi-critical transient dynamic balance method based on rising speed response information of flexible rotor system
YUE Cong, REN Xing-min, DENG Wang-qun, YANG Yong-feng
2013, 28(11): 2593-2599.
Abstract PDF(1082KB) icon1880 icon933
Abstract:
A multi-plane and multi-critical transient dynamic balance method was proposed by rising speed response information of flexible rotor.The flexible rotor multi-critical speed balance correction quantity under the optimal algorithm was put forward.The overall balance can be realized by imbalance information of three times rise-critical-speed re-sponse to suppress multi-critical amount of unbalance simultaneously. Numerical simulation with dynamic balance method applies to two-disk rotor model of two-critical unbalance and three-disk rotor model of three-critical unbalance, respectively. The results show that the method could effectively control the amplitude fluc-tuation of whole rotor system while decreasing critical speed amplitude rate up to 60%-80%.
Fault diagnosis of roller bearings based on chirplet path pursuit and order cyclostationary demodulation
XU Ya-jun, YU De-jie, LIU Jian
2013, 28(11): 2600-2608.
Abstract PDF(1239KB) icon1330 icon962
Abstract:
Aim at the problem of fault diagnosis of roller bearings with rotating speed fluctuation, a method for the fault diagnosis of roller bearings was proposed by combining the chirplet path pursuit algorithm with the order cyclostationary demodulation method. In this proposed method, the chirplet path pursuit algorithm was used to obtain the bearing fault characteristic frequency. According to the bearing fault characteristic frequency, the envelope of the time domain vibration signal with rotating speed fluctuation was resampled at constant angle increments in angular domain, and the obtained angular domain steady signal was dealt by cyclostationary demodulation. The slice demodulation spectrum was then acquired and used to diagnose the fault of roller bearings. Simulation analysis and application examples show that the proposed method can exactly extract the outer and inner fault characteristics of roller bearings with rotating speed fluctuation. Compared with the envelope order spectrum method based on Wigner-Ville distribution, the proposed method can obtain more distinct fault characteristic of roller bearings.
Improved unstructured grid optimization method based on spring analogy
WANG Guang-xing, YUE Ming
2013, 28(11): 2609-2614.
Abstract PDF(1301KB) icon1128 icon933
Abstract:
An improved spring analogy method for unstructured grid optimization was presented. The method can control the cell density of grid and improve the quality of cells. Non-uniform stiffness spring was used to adjust the cell density of grid in spring analogy method; vertex spring model with revised stiffness and segment spring model with changeable initial balance length were adopted to overcome the drawback of original spring analogy smoothing algorithm, which may lead to local non-smoothness in the grid. The method has kept advantages of original method, such as easy implementation, simple date structure, improved ability of optimization, so the ratio of minimum length to maximum length was updated from 0.24 to 0.42(closer to 1 is better) in the example hereto, helping to optimize the tangled grids also.
Numerical investigation of nozzle flow separation control by injecting secondary jet from nozzle exit
LI Bo, WANG Yi-bai, YANG Li-jun, CHENG Cheng
2013, 28(11): 2615-2620.
Abstract PDF(914KB) icon1378 icon803
Abstract:
The subscale nozzle model of a liquid rocket engine was researched.The corresponding flow field configurations were analyzed.The influence of main parameters of the secondary jet injector on control effectiveness was analyzed,including the injection angle,the area ratio and the total temperature of its working fluid.The results indicate that,when the secondary jet injector is adopted,the nozzle inlet total pressure which can make the nozzle reach full flow decreases 37.8%;as the injection angle increases from 0° to 25°,the nozzle flow separation location moves about 0.01m towards the nozzle throat,and the control effectiveness of the device decreases significantly;as the total temperature of the injector's working fluid increases from 300K to 1500K,the nozzle flow separation location moves about 0.005m towards the nozzle exit,and the control effectiveness of the device increases slightly. The area ratio has no effect on flow separation location when no flow separation occurs in the secondary jet injector,otherwise,the control effectiveness of the device will decrease.
Two-phase flow numerical calculation of H2O2/HTPB hybrid rocket engine with diaphragm in grain
WANG Peng-fei, TIAN Hui, YU Nan-jia, CAI Guo-biao
2013, 28(11): 2621-2626.
Abstract PDF(965KB) icon1392 icon915
Abstract:
The effect of diaphragm in grain on combustion performence of hybrid rocket engine was studied.The standard φ 100mm hybrid rocket engine of Beijing University of Aeronautics and Astronautics was selected as a computational model,and 98% hydrogen peroxide(H2O2)/hydroxyl terminated polybutadiene (HTPB) was combined as propellant;different hole diameters of diaphragm setting at different grain positions were computed by 2-D axial symmetry and gas-liquid two-phase flow model.The results show that smaller diameter of diaphragm hole and the diaphragm setting at positions ranging from 50% to 70% of grain length can obtain the largest averaged regression rate of fuel and the highest combustion efficiency.This conclusion will provide a theory evidence for design of the diaphragm.
Design of data acquisition system for solid-liquid dynamic sounding rocket
XIN Jie, CAI Guo-biao, SONG Jia
2013, 28(11): 2627-2633.
Abstract PDF(851KB) icon1265 icon882
Abstract:
For solid-liquid dynamic sounding rocket under test and aero experiment,the real-time data acquisition and storage problem of thrust,fuel supply rate and blow-off system should be solved.A data acquisition system was thus designed and implemented to monitor,acquire and save output data of some relevant important facilities on the solid-liquid dynamic sounding rocket.Based on STM32F103RB microcontroller,data acquisition,storage and transmission circuits were designed.Moreover,under the Real View MDK integrated development environment,the programs of test and control were compiled by language C.Finally,the software and hardware were tested jointly by Real View ULINKR simulator.The joint debugging results verify that the system functions such as power supply control,sampling frequency and working condition storage can meet the design requirements,helping to complete supervisory,acquisition and storage missions for important facilities on the solid-liquid dynamic sounding rocket.The system can be applied to different categories of solid-liquid dynamic sounding rocket only through modification of testing control program.
Adaptive global fast non-singular Terminal sliding mode control for aero-engine
MIAO Zhuo-guang, XIE Shou-sheng, ZHANG Bo, REN Li-tong, WANG Li-guo, WU Yong
2013, 28(11): 2634-2640.
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Abstract:
A method for adaptive global fast non-singular Terminal sliding mode control was put forward according to the characteristics of aero-engine's control system with the robustness and the capability of fast response as well as the singularity shortcoming of Terminal sliding mode control. The devised fast non-singular Terminal sliding surface solved these two problems of the singularity and the slow convergence speed when the sliding surface was far away the equilibrium point. Equivalent interferences were estimated by self-adaptive method without need to know the upper boundary of interferences of aero-engine. Then the stability was analyzed based on the theory of Lyapunov. Simulation results show that the devised Terminal sliding mode controller has good dynamic performance;the response of state output is fast, and the regulation time is about 2s, without steady error, overshoot and singularity.

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