2017 Vol. 32, No. 11

  Previous Issue | Next Issue 
Display Method:
Numerical computation and analysis of impingement/effusion cooling performance on concave wall
2017, 32(11): 2561-2567. doi: 10.13224/j.cnki.jasp.2017.11.001
Abstract PDF(924KB) icon1049 icon790
Abstract:
Fluid/solid conjugated heat transfer numerical computation was conducted to study the impingement/effusion cooling performance on concave wall of different schemes by Fluent software, and the trend of wall temperature and the integrative cooling effectiveness were obtained, while the wall temperature test of the concave wall was carried out. The results indicated that: (1) the discharge coefficient and the total pressure loss coefficient were relevant to the equivalent hole area, and the discharge coefficient and the total pressure loss coefficient of different schemes were equivalent when the equivalent hole area was uniform. (2) When the equivalent hole area was uniform, the integrative cooling effectiveness could be improved if the effusion hole area was expanded or the impingement hole area was decreased. (3) The integrative cooling effectiveness was affected by impingement and effusion holes arrangement, and the integrative cooling effectiveness of hexagonal arrangement was better than the integrative cooling effectiveness of rhombus arrangement when the hole number, hole diameter and the hole area were uniform.
Numerical simulation and experiment of triple swirler combustor
2017, 32(11): 2568-2575. doi: 10.13224/j.cnki.jasp.2017.11.002
Abstract PDF(970KB) icon1463 icon772
Abstract:
In order to study the combustion technology of the high temperature rise triple swirler combustor, numerical simulation was conducted for single dome triple swirler combustor by means of CFD technology. Structured grids were meshed on computational domain of the triple swirler combustor. Realizable k-ε turbulent model and PDF （probability density function）combustion model were applied to the numerical simulation. The flow and combustion fields of the combustor and combustor performances in every aspect were obtained. Furthermore, wall temperature of flame tube, exit temperature distribution and combustion efficiency as well as smoke number were investigated experimentally. The results indicated that the temperature rise of triple swirler combustor was 1130K with 99％ combustion efficiency and good wall temperature distribution. The smoke number was only 20. The mathematical models and numerical methods were reasonable and the simulation results accorded well with the experimental data. The numerical results provide an important reference to the design of the triple swirler combustor.
Effect of the second inlet location on heat transfer distribution in rotating wedgeshaped channel
2017, 32(11): 2576-2584. doi: 10.13224/j.cnki.jasp.2017.11.003
Abstract PDF(1127KB) icon1030 icon659
Abstract:
When the inlet Reynolds number was fixed at 15000, the maximum mass flow rate ratio (the ratio between the second inlet mass flow rate and major inlet mass flow rate) was 04, and the highest rotation number was 023, the heat transfer distribution in a wedgeshaped channel with three different locations of second inlet was investigated by test. The results showed that, under nonrotating condition, heat transfer was improved substantially in the vicinity region of second inlet. Under rotating condition, the upstream region affected by second inlet enlarged, lateral flow extraction slowed down, heat transfer difference between the local leadingwall and trailingwall reduced, which was minimized when the local heat transfer efficiency reached the maximum. To promote average heat transfer efficiency of channel, and compensate the negative effects induced by rotation, the second inlet injection should be placed in the uppermiddle part of channel, and mass flow rate ratio should be controlled below the corresponding critical value.
Anisotropic heat transfer model of finger seal based on porous media
2017, 32(11): 2585-2595. doi: 10.13224/j.cnki.jasp.2017.11.004
Abstract PDF(984KB) icon1173 icon689
Abstract:
An anisotropic heat transfer model was built by theoretically analyzing the contact and anisotropic heat transfer characteristics coupled finger seal and fluid flow within the structure on the basis of porous model. Then, an anisotropic heat transfer numerical calculation model was developed on the basis of userdefined scalar (UDS) function of commercial software Fluent, and the heat transfer and flow characteristics of finger seal were simulated. Results showed that the effective thermal conductivity tenser of finger beam and finger foot was related to the factors of porosity, radial and circumferential position, and axial contact resistance. The highest temperature of finger seal appeared slightly downstream the contact surface between finger foot and rotor. Besides, compared with isotropic heat transfer model, the temperature decreased greatly at radial and axial directions in finger foot and lower part of finger beam zones while using anisotropic heat transfer model, however, it remained unchanged in circumference both of them. Seal leakage increased with the increasing pressure differential but kept stable with the increasing rotation speed. The height temperature decreased with the increasing pressure differential but increased with the increasing rotation speed.
Comparative study on the effects of hydrogen and hydrogen peroxide additions on combustion characteristics of n-decane/air mixtures
2017, 32(11): 2596-2603. doi: 10.13224/j.cnki.jasp.2017.11.005
Abstract PDF(978KB) icon1217 icon664
Abstract:
Hydrogen (H2) and hydrogen peroxide (H2O2) are useful promoters of hydrocarbons combustion due to their high reactivity. To explore the effects of liquid hydrogen and liquid hydrogen peroxide additions on combustion characteristics of jet fuel, a comparative computational study was conducted with ndecane as a single component surrogate for the practical jet fuel. It was founded that H2O2 addition can significantly shorten the ignition delay times of fuel/air mixtures at all condition considered, while H2 addition had negligible effect on the ignition delay times at low temperature around 1100K compared with the notable effect at high temperature around 1600K. The H2O2 addition showed a more significant effect on increasing the laminar flame speeds than H2 addition. The H2O2 and H2 additions slightly reduced the emission index of CO (EICO), but increased the emission index of NO (EINO). EICO and EINO did not vary much with H2 and H2O2 addition levels at fuel lean and low pressure conditions. For rich fuel and high pressure conditions EICO decreased and EINO increased with increasing H2O2 and H2 additions; however, effects of H2O2 addition on both EICO and EINO were much significant than H2 addition.
Experiment on diffusion coefficient of carbon dioxide in RP-3 aviation fuel
2017, 32(11): 2604-2608. doi: 10.13224/j.cnki.jasp.2017.11.006
Abstract PDF(747KB) icon1071 icon700
Abstract:
A experiment apparatus based on the pressure decltion method was constructed, and the preliminary results concerning the carbon dioxideWater diffusion system at 29815K were in reasonable agreement with other report. Then it was used to measure the gas pressure versus time for carbon dioxideRP3 aviation fuel system under a temperature range from 28315K to 333.15K. The fitting curve agreed with the experimental data perfectly, the diffusion coefficient values at different temperatures were of magnititude 10-8m2/s. From the experimental result, the relationship between the mass diffusion coefficient and temperature satisfied the Arrhenius rate law. A model of prediction of diffusion coefficient of carbon dioxide in RP3 aviation fuel was built according to existing data in the experiment. To verify the accuracy of the prediction model, more experiments under the conditions of 253.15, 263.15K and 273.15K were conducted. The experiment results matched the fitting equation with accuracy and extensionality.
Numerical studies on film cooling performance of turbine vane leading edge with counter-inclined structure
2017, 32(11): 2609-2618. doi: 10.13224/j.cnki.jasp.2017.11.007
Abstract PDF(1276KB) icon1183 icon796
Abstract:
Numerical studies were performed for the film cooling performance of counterinclined filmhole rows, presenting advantage in manufacturing relative to the usually used parallelinclined filmhole row structure, on a turbine vane leading edge model. Two types of counterinclined filmhole rows were studied, including collinear counterinclined filmhole row and noncollinear counterinclined filmhole row. The distributions of film cooling effectiveness and heat transfer coefficient were obtained for the blowing ratios of 05, 10, 15 and 20. The effect of hole pitch on the film cooling effectiveness and heat transfer coefficient was also studied. Results show that the film cooling performance of counterinclined filmhole rows is not weakened compared with the traditional parallelinclined filmhole row structure. The film cooling effectiveness of the two counterinclined filmhole row structures decreases with the increase of blowing ratio, while the heat transfer coefficient increases. The change of inclination structure of filmhole row has very little effect on the heat transfer coefficient in the downstream region, while the increase of hole pitch can influence the values of heat transfer coefficient as well as the film cooling effectiveness in a relatively notable way.
Experiment on surface heat transfer characteristic of high rib in high pressure turbine casing
2017, 32(11): 2619-2628. doi: 10.13224/j.cnki.jasp.2017.11.008
Abstract PDF(1011KB) icon1065 icon622
Abstract:
Abstract：According to the multilayer high pressure turbine case applied in an active clearance control system, a typical compound cooling structure consisting of impingement with high ribs and embedded bolts was investigated. The effects of jet Reynolds number, the ratio of height of rib to jet holes diameter on local and average heat transfer coefficients were experimentally studied. It was found that the heat transfer coefficients of target surface were improved with the increase of jet Reynolds number, while the growth rate slowed down. The highest average heat transfer coefficient was observed at the region near the exhaust channel when three rows of jet holes were used. The experimental results showed that the heat transfer coefficients on high rib surfaces were influenced by both the height of rib and impinging Reynolds number. Increasing the height of rib led to higher heat transfer coefficients, and this trend becomed more distinguished in large Reynolds cases.
Oxyfuel combustion of propane based on rapidly mixed tubular flame technology
2017, 32(11): 2629-2637. doi: 10.13224/j.cnki.jasp.2017.11.009
Abstract PDF(988KB) icon1236 icon828
Abstract:
An inherently safe technique of rapidly mixed tubular flame combustion, with the fuel and oxidizer individually injected into a combustor, was adopted to investigate the oxyfuel combustion of propane. The variations of flame structure and combustion stability with oxygen mole fraction were addressed. Based on propane/air combustion, it was found that the rapidly mixed combustion could obtain almost the same flame structure as that of the premixed combustion. Thereafter CO2 was used as the diluent, and combustion tests were conducted under different oxygen mole fractions. Results illustrated that when oxygen mole fraction was no more than 05, a uniform and stable tubular flame can be established from lean to rich limit; by increasing oxygen mole fraction to 06, the laminar flame became nonuniform in structure, however, the flame was stable; by raising oxygen mole fraction to 07, the stable tubular flame was merely obtained at lean combustion, and oscillatory combustion appeared when the equivalence ratio of 1.0. By further increasing oxygen mole fraction, the oscillation region was expanded. The combustion range for propane/oxygen mixture diluted by N2 and CO2 was examined when oxygen mole fraction was no more than 04. It was found that the flammable range diluted by N2 was wider than that diluted by CO2, and the minimum oxygen mole fraction to sustain propane/oxygen combustion diluted by CO2 was 018, higher than that of 0125 diluted by N2.
Study on thermometry of leading edge of rotating turbine blade by thermochromic liquid crystal
2017, 32(11): 2638-2645. doi: 10.13224/j.cnki.jasp.2017.11.010
Abstract PDF(1025KB) icon1004 icon817
Abstract:
A temperature measure system for the leading edge of the rotating turbine blade was established based on stroboscopic imaging technique and thermochromic liquid crystal, while the temperature field characteristics of the leading edge were studied under different rotational speeds. The experiment result showed that this system was workable, and presented enough resolution and accuracy; the film cooling efficiency of the leading edge decreased with the increasing rotation number, and the disequilibrium of the film cooling efficiency on the pressure and suction surfaces increased.
Threedimensional numerical simulation for heat and mass transfer of the evaporator in a flat miniature loop heat pipe
2017, 32(11): 2646-2652. doi: 10.13224/j.cnki.jasp.2017.11.011
Abstract PDF(896KB) icon1212 icon696
Abstract:
In order to analyse the heat and mass transfer of the evaporator in a flat miniature loop heat pipe, a multidomaincoupling mathematical model was developed and threedimensional numerical simulation was implemented using FLUENT software. According to the results, the evaporator heat transfer characteristics showed obvious difference at different heat loads. Evaporator temperature was not only determined by the heat load, but much affected by the two heat transfer mechanisms on the wick surface, i.e: capillary evaporation and heat conduction. Compared with high heat load (Q=120W) and low heat load (Q=40W) condition，all parts of the evaporator under medium heat load (Q=80W) condition were at lower temperature. For all of the three different heat loads, inverse heat conductions from the wick were larger than heat leak from the side walls, therefore the highesttemperature region in compensation chamber easily presented near the wick. Backflow from the condenser flowing into the evaporator formed two large eddies in compensation chamber. Such a flow characteristic is conducive to chilling wick. When the heat load added on the system matches its condensation capacity, the flow and heat transfer characteristics of the system is optimal.
Refractive index field measurement of random medium based on background oriented schlieren
2017, 32(11): 2653-2658. doi: 10.13224/j.cnki.jasp.2017.11.012
Abstract PDF(865KB) icon1005 icon685
Abstract:
Targeting the problem of light propagation effect caused by complex flow field, a method for measuring the complex refractive index field based on the background image was proposed. The calculation method and derivation process of refractive index field distribution based on particle image offset were given, and the resolution and sensitivity of the method were analyzed theoretically. On this basis, experiments were carried out on the distribution of the refractive index field above the flame. The experimental image was processed by using the particle image velocimetry (PIV) method. Result showed that, the maximum and minimum refractive index of the air was 100029 and 100009, respectively, according to the experimental measurement, and the effective value was less than 00001. The experimental results showed that this method had high accuracy and can realize the realtime accurate measurement of the complex refractive index field.
Vibration response experimental verification and fatigue analysis of thinwalled structures to thermalacoustic loads
2017, 32(11): 2659-2671. doi: 10.13224/j.cnki.jasp.2017.11.013
Abstract PDF(1333KB) icon1149 icon628
Abstract:
Metallic thinwalled structure under thermalacoustic environment shows complex nonlinear vibration response characteristics of large deflection, affecting fatigue performances and life of structure. Thermalacoustic responses of superalloy thinwalled rectangular plates with four edges clamped were calculated by combining finite element method and reduced order modal method. Research showed that buckling structures could exhibit snapthrough motions which were decided by relative strength between thermal loads and acoustic loads, and stress cycle showed a triangular distribution. The Miner linear accumulative damage theory was employed in conjunction with improved rain flow counting method and Morrow mean stress model to calculate thermalacoustic fatigue life. From prebuckling to critical buckling, the damage level of stress cycle increased significantly from 10-5 to 10-4, and with the increase of temperature, the fatigue life showed a trend of decrease at first and then increase. The thermalacoustic experiment of thinwalled structure was carried out to make a comparison between the results of simulation and experiment. Results showed that the deviation of structural modal frequencies was less than 1Hz, and strain responses of calculation and experiment results had a good alignment, validating the effectiveness of calculation method and model to thermalacoustic responses.
Experimental comparison of vibration isolation ability of centralized and uncentralized squeeze film damper
2017, 32(11): 2672-2679. doi: 10.13224/j.cnki.jasp.2017.11.014
Abstract PDF(1084KB) icon1179 icon520
Abstract:
In order to compare experimentally the vibration isolation ability of centralized and uncentralized squeeze film damper(SFD) with/without a centralized spring, a series of experiments with different rotor unbalance masses and radial clearances were done in a multidisk flexible rotor system with the centralized and uncentralized SFD. It was shown that both the centralized SFD and the uncentralized SFD can effectively isolate the vibration of the rotor system with comparison to the rotor system supported on the rolling ball bearings or the centralizing springs. In the rotor system with the centralized SFD, when the action of centralized SFD was weaker than that of the centralized spring, the critical speeds of the rotor system can be adjusted by the stiffness of centralized spring, and located at the critical speeds of the rotor system with the centralized springs. However, when the action of SFD was stronger than that of the centralized spring, the critical speeds of the rotor system cannot be adjusted by the stiffness of centralized spring and located at the critical speeds of the rotor system with the rigid mounts. The nonlinearity in the rotor system with the uncentralized SFD was more complex than that with the centralized SFD; in additional to the main resonance, the sub and superresonances were observed.
Dynamic performance of super micro high speed air bearings
2017, 32(11): 2680-2686. doi: 10.13224/j.cnki.jasp.2017.11.015
Abstract PDF(807KB) icon1031 icon623
Abstract:
The dynamic performance of micro rotor (radius of 1985mm) was numerically and experimentally investigated.In numerical simulation, transient twoway fluidsolid coupling simulation was carried out by using ANSYS. The dynamic process of rotors position in initial stage under the effects from air bearings was simulated. The results showed that the displacement process of rotor presented a vibration motion with reducing amplitude as the elapse of time and the rotor ultimately stabilized to an equilibrium position. For higher levels of supply pressure of thrust bearing, larger range of displacement of rotor appeared and the rotor spent more time reaching stabilization. Besides, the positive relationship between air bearing gap height and bearing flow rate was revealed in results. In corresponding experiments, the experiment results were in good agreement with simulations. The numerical and experimental results show that the rotor has a greater risk of collision because the range of displacement of rotor is bigger at higher level of supply pressure of thrust bearing. Supply pressure of 70927Pa is more suitable for thrust bearing in initial stage.
Prediction of strain energy of fiber reinforced cantilever beam structure under base excitation based on semitheoretical method
2017, 32(11): 2687-2694. doi: 10.13224/j.cnki.jasp.2017.11.016
Abstract PDF(807KB) icon958 icon494
Abstract:
Semitheoretical method was proposed to predict the strain energy of fiber reinforced cantilever beam under base excitation. Firstly, strain energy analysis model of fiber reinforced composite beam structure was established. Then, the principle of semitheoretical method to predict strain energy of fiber reinforced cantilever beam was elaborated, and the corresponding prediction procedures of strain energy were also described. Finally, the vibration displacement responses of such composite beam structure under base excitation of certain level were measured and the correctness of strain energy analysis model was verified. It was proved that the semitheoretical method can be used to analyze and predict the strain energy of composite beams, and the predicted results were also compared with those of aluminum alloy beams with the same dimension parameters of such composite beams. It can be found that the strain energy of fiber reinforced cantilever beam was 24%-36% lower than that of aluminum alloy beam under the same excitation amplitude, and strain energy index indeed can be used to evaluate the damping capacity of composite structure compared with metal structure.
Model updating of an aeroengine casing based on the mixed boundary substructure
2017, 32(11): 2695-2704. doi: 10.13224/j.cnki.jasp.2017.11.017
Abstract PDF(928KB) icon1054 icon540
Abstract:
A complex structure finite element model updating method based on the mixed boundary component mode synthesis (CMS) was proposed. The major steps of the proposed finite element model updating method include: (1) substructure partition, partition of the updating area into substructure and residual structure according to the junction ways. (2) Reduction and assembly, reduce the internal degree of freedoms (DOFs) to the mixed boundary DOFs by mixed boundary CMS, and assemble the reduction matrix of substructure into the residual structure physical matrix. （3) Updating, assemble residual structure model updating by sensitivity analysis. The proposed approach was applied to the aeroengine casing refined finite element modeling and model updating. For the local junction parameter updating, the maximal error was 064% for the substructure model updating method, and the computational efficiency improved by 515 times. These results demonstrate that the method can guarantee the accuracy of the model updating, and improve the numerical computational efficiency of the largescale complex structure.
Responses of pipe system with flexible clamp under harmonic excitation
2017, 32(11): 2705-2712. doi: 10.13224/j.cnki.jasp.2017.11.018
Abstract PDF(1497KB) icon1096 icon531
Abstract:
For analysis of vibration of aeroengine pipe system with flexible clamp, the stiffness characteristics of a flexible clamp and the effect of the flexible clamp on the pipe system response were studied, respectively. Considering the fluidstructure interaction, a dynamic model with pipe and flexible clamp was proposed based on the finite element model. The Newmark numerical integration was then utilized to obtain the timedomain responses. The stiffness of the flexible clamp was derived analytically and verified by the test. The result showed that the stiffness of the flexible clamp was piecewise linear stiffness. Responses of a pipe system with flexible clamp under harmonic base excitation were simulated, and the effects of the flexible clamp stiffness on the nonlinear dynamic behavior of the system were also discussed in detail. The results show that the amplitudefrequency curves of the responses become obviously nonlinear with the increase of the flexible clamp stiffness asymmetry. Within certain excitation frequency ranges, both subharmonic and multiharmonic responses could be found in the system responses. The natural frequencies decreases with the increase of flow velocity and pressure.
Comparative experiment of hightemperature crack propagation behaviors for four kinds of typical titanium alloys
2017, 32(11): 2713-2720. doi: 10.13224/j.cnki.jasp.2017.11.019
Abstract PDF(1247KB) icon1180 icon542
Abstract:
Fatigue experiments were carried out on four kinds of titanium alloys of TC18, TC21, TC4DT and Ti6Al4V/ELI subjecting to constant amplitude loading at two temperatures of 25℃ and 250℃, so as to determine the fatigue crack propagation behaviors. Fatigue crack propagation behaviors at different temperatures were analyzed and compared with each other, and the interaction mechanisms between hightemperature and fatigue load were deduced from fractographical studies by using scanning election microscope (SEM) analysis. Results showed that there were great differences between crack propagation rate behaviors of different titanium alloys at different temperatures. Fatigue surfaces at high temperature had more secondary cracks and showed more significant light yellow than those at room temperature. Fatigue crack propagation of titanium alloy was governed by the interaction effect between hightemperature and fatigue load due to the crack closure and oxidation effects.
A stiffness prediction model for threedimensional four directional composites based on mesoscopic structure
2017, 32(11): 2721-2728. doi: 10.13224/j.cnki.jasp.2017.11.020
Abstract PDF(830KB) icon1035 icon497
Abstract:
The interior unit cell, surface unit cell and corner unit cell of threedimensional four directional composites were established in mesoscopic scale, and the models considered the changes of the yarn cross section and mutual extrusion. Applying the corresponding periodic boundary conditions, and using the stiffness volume average method, the threedimensional four directional composites stiffness prediction models were established. The longitudinal elasticity modulus of trimming and nontrimming threedimensional four directional carbon/carbon composites were predicted. The results show that the predicted values of 8, 13, 16, 21mm width threedimensional four directional carbon/carbon composites and experimental values have 183%, 58%, 42% and 5% errors,respectively. The prediction results have a higher precision when widening the specimens, and the three unit cells model has good precision in longitudinal elasticity modulus which is much better than that of interior unit cell method when the width of specimens is over 13mm.
Test of the weft mechanical properties of 2.5D woven composites
2017, 32(11): 2729-2736. doi: 10.13224/j.cnki.jasp.2017.11.021
Abstract PDF(876KB) icon1043 icon517
Abstract:
The mechanical properties and tensiontension fatigue life of 25D resin base woven composites at various temperatures, including room temperature (20℃) and hightemperature (180℃), were obtained by static tensile and tensiontension fatigue tests. Based on macroscopic tests, the damage modes and failure mechanism of the materials subjecting to static tensile and tensiontension fatigue loadings were discussed. Meanwhile, the relationship between residual strength and static strength was compared, and the influence of temperature on the static tensile and fatigue life was then analyzed. The results show that the weft modulus is not sensitive to temperature, ranging from 20℃ to 180℃, but the weft strength and fatigue life have a downward trend with the temperature increase. The weft fatigue life experiences a quite short cycle (less than 104 cycles) prior to the ultimate failure at high temperature and high stress level (higher than 80% static strength), however, the corresponding life tends to be 106 cycles when the stress level declines by only 2%. Additionally, the elevated residual strength is higher than the static strength tested at the same temperature.
Variable control flow supply angle regulation scheme of vortex valve solid rocket motor thrust modulation
2017, 32(11): 2737-2742. doi: 10.13224/j.cnki.jasp.2017.11.022
Abstract PDF(843KB) icon1115 icon515
Abstract:
Numerical calculation and experimental study on the performance of the variable control flow supply angle regulation scheme of vortex valve solid rocket motor were carried out. Numerical results showed that the variable control flow supply angle regulation scheme can be used to achieve a very good performance, the maximum thrust regulation ratio of the vortex valve solid rocket motor exceeded that of the straight mass augmentation motor by 26%, and the pressure ratio increased with the decrease of the control flow supply angle. Experimental results showed that the variable control flow supply angle regulation scheme was feasible and the superiority of “gasgas” regulation was verified. The variable control flow supply angle regulation scheme provided a technical approach for the realization of thrust regulation of solid rocket motor.
Research on blowing wing based on lift and thrust mechanism of fanwing wing
2017, 32(11): 2743-2751. doi: 10.13224/j.cnki.jasp.2017.11.023
Abstract PDF(1040KB) icon928 icon662
Abstract:
Based on the numerical calculation and analysis of the mechanism of the lift and thrust force of the fan wing aircraft, a scheme for the wing of fanwing aircraft-blowing wing was presented. The mechanism of the lift force of the wing was analyzed and the blowing wing model was established. The numerical calculation method of the wing was established and a numerical example was verified. It was proved that the blowing wing had the same vortex induced lift and thrust mode as that of the fanwing by comparing the relative static pressure distribution curve, velocity nephogram and pressure nephogram. The blow up speed of a blowing wing was defined and the relationship between lift and thrust of two wings with flow speed and angle of attack was compared. The result indicated that when the angle of attack was greater than 20 degrees, the thrust of the blowing wing was nearly 5 times less than that of the fan wing. Under normal flight conditions, the lift and thrust force of the blowing wing is similar to the fan wing, which can be replaced. It provides an idea for the optimizing design and lift enhancement of aircraft.
Improvement of powered lifting scheme on the saggingcharacteristic of blendedwingbody aircraft
2017, 32(11): 2752-2760. doi: 10.13224/j.cnki.jasp.2017.11.024
Abstract PDF(834KB) icon959 icon684
Abstract:
Blendedwingbody aircraft frequently shows the sagging phenomenon, which is a safety sensitive problem in takeoff and landing. Focusing on the problem, a powered lifting scheme by use of ductedfan in wings was presented. Aerodynamic effect of the powered lifting system on flight was analyzed. A matched design and assessment method for the powered lifting system was established, and the main constraints of the layout were integrated. Taking the thrust weight ratio of the system, pitching trim, maneuverability and stability into consideration, a blendedwingbody drone was used as example and the powered lifting system and its layout scheme were presented. For smooth transition of flight phases, an attitude stabilization control law was further introduced. Flight tests show that the powered lifting device can mitigate the sudden increase of sink rate and height sagging phenomenon due to elevator deflection in approaching stage. Meanwhile, the scheme can reduce the takeoff and landing velocity by over 20%, and the scheme is apt to be implemented on small size of blendedwingbody aircraft.
CFD simulations of jet in crossflow with modified SA turbulence model
2017, 32(11): 2761-2768. doi: 10.13224/j.cnki.jasp.2017.11.025
Abstract PDF(904KB) icon1203 icon468
Abstract:
In order to improve the accuracy of simulating jet in crossflow(JICF), SpalartAllmaras (SA) turbulence model was improved by introducing strain rate tensor into the turbulence production term because of the significant influence of shear in JICF. The JICF with velocity ratios of 05 and 15 was simulated by the modified SA turbulence model. According to the validation with experimental data, the results showed that accuracy of predicting JICF with modified SA model was promoted; mechanism of the modified parts in S-A model was also analyzed. Modified S-A model, k-ε model, Reynolds stress model(RSM) and large eddy simulation(LES) were compared in the simulations of JICF. The results showed that the modified S-A model performed best at the velocity ratio of 0.5, and had a similar accuracy to other models at the velocity ratio of 1.5; in addition, the results were analyzed reasonably.
Friction analyses of the rocket sled system
2017, 32(11): 2769-2776. doi: 10.13224/j.cnki.jasp.2017.11.026
Abstract PDF(869KB) icon897 icon446
Abstract:
Based on the nonlinear and unsteady motion and friction characteristics analyses of the rocket sled in dynamic testing, the dynamic modeling and numerical simulation of the rocket sled were carried out. Meanwhile, the dynamic and aerodynamic characteristics of the rocket sled in different motion states were analyzed. The results showed that the drag coefficient was about 0.58, and the lift coefficient was about 0.003 during the velocity range from 60m/s to 90m/s. The aerodynamic force of the rocket sled mainly manifested as drag force, and the lift was less than the rocket sled weight, about 0.5%-1.2% of the weight. On the other hand, sliding velocity was the main affecting factor of the friction coefficient. With the increase of the sliding velocity, the friction coefficient decreased. Considering the results from both simulation and tests, the function of friction coefficient in terms of velocity was established in the power form with a coefficient of 2.554, and an exponent of -0.756. The predictive values of the rocket sled calculated by the friction coefficient formula under different conditions agreed well with the experimental data.
Simulating shocktube flow with a twodimensional compact fourth order lattice model
2017, 32(11): 2777-2783. doi: 10.13224/j.cnki.jasp.2017.11.027
Abstract PDF(830KB) icon885 icon472
Abstract:
In order to improve the stability of the lattice model, a new twodimensional compact fourth order lattice model, ie, D2Q37A,was constructed based on the Hermite expansion. The stability of D2Q37A and the one proposed by Philippi (D2Q37B) were compared. Under the same collision frequency, D2Q37A can be applied to the onedimensional shock flow with the higher initial density ratio comparing with D2Q37B.That means D2Q37A was more stable than D2Q37B.An implementation of boundary conditions for high order lattice models was proposed in details. The implementation maintained the streamingcollision mechanism ensuring the particle feature of the LBM（lattice Boltmann method）. This new lattice model and implementation of boundary conditions were applied to onedimensional shock tube problem and the result of simulation was consistent with the analytical solution. The results show the proposed boundary condition scheme is practicable. The proposed boundary scheme can be employed by other type of flow and boundary.
Experiment on static characteristics of plasma synthetic jet actuator with oblique orifice
2017, 32(11): 2784-2790. doi: 10.13224/j.cnki.jasp.2017.11.028
Abstract PDF(818KB) icon931 icon482
Abstract:
A plasma synthetic jet actuator with oblique orifice was designed. The discharge characteristics and flow field characteristics were researched by electric parameter measurement system and highspeed Schlieren technology. Results showed that compared with the actuator with normal orifice, the injection flow induced by the jet actuator with oblique orifice tended to attach the wall and behave with significant asymmetry, enhancing the jet flow control capability. Moreover, the effect of buoyancy on the evolution of high temperature plasma jet flow was observed, the normal velocity induced by the buoyancy effect altered the flow direction, and this effect got stronger at the end of the evolution.
Modeling and simulation of thrust reverser hydraulic actuation system based on AMESim
2017, 32(11): 2791-2799. doi: 10.13224/j.cnki.jasp.2017.11.029
Abstract PDF(1035KB) icon1172 icon639
Abstract:
Based on the structure and principle of thrust reverser hydraulic actuator system, the mathematic model and AMESim model of worm gear drive, screw nut drive and actuation system was established through theoretical analyze. Take a kind of actuation system for simulation, the change law of displacement, synchronization, force and the effect of different screw lead angle, worm gear transmission ratio and oil supply pressure to performance was studied. Result showed the model can accurately simulate the working state of the extension and retraction of the actuation system, which provided a platform for the design parameter selection, force analysis and fault diagnosis of the thrust reverser actuation system.
Constraint method of calculating tooth bending deformation of hypoid gears in LTCA
2017, 32(11): 2800-2807. doi: 10.13224/j.cnki.jasp.2017.11.030
Abstract PDF(901KB) icon1002 icon515
Abstract:
Given that the bending deformation obtained from loaded tooth contact analysis (LTCA) of spiral bevel and hypoid gears contains deformations due to flexibility and shearing deformations, a constraint method of the tooth finite element model used in LTCA was proposed. This constraint method added a finite element model which fixed the nodes in the center of the tooth and the inner circle on the basis of the original constraint method. The process to obtain the normal flexibility matrix of tooth surface was also proposed. To verify the correctness of this constraint method, LTCA was conducted using this constraint method and the original one. Load contact experiment was conducted at the same time. Result showed that the constraint method mainly affected the loaded contact pattern. The loaded contact pattern obtained by the original constraint method reached the toe of the tooth under the maximum torque, while there was still 3-4mm away from the toe of the loaded contact pattern obtained by this constraint method. The loaded contact pattern obtained from this constraint method was in agreement better with the experiment.
Accuracy analysis of unsteady numerical simulation methods for axial flow compressor
2017, 32(11): 2808-2816. doi: 10.13224/j.cnki.jasp.2017.11.031
Abstract PDF(1013KB) icon819 icon474
Abstract:
Taking Stage 35 singlestage axial compressor as model, the predictions obtained using the nonlinear harmonic, phase lag and domain scaling method were compared respectively with the results obtained using a conventional half annulus unsteady simulation and experiment. The purpose was to analyze the numerical accuracy and computational efficiency of the three methods. Numerical results indicated that the three methods can all achieve same accuracy level as the half annulus unsteady simulation in terms of timeaveraged parameters of flow field, but the spectrum characteristics obtained by domain scaling method revealed significant differences due to the geometry scaling, especially the amplitude in fundamental harmonic. The precision of the phase lag method was higher than domain scaling method in the prediction of amplitude in fundamental harmonic, however, it was usually contrary in other harmonics. Furthermore, the unsteadiness predicted by nonlinear harmonic method can not achieve the same accuracy as the phase lag and domain scaling method.

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

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