2001 Vol. 16, No. 2

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Prospects of the Aeroengine Control Development in the Early Time of the 21st Century
SUN Jian guo
2001, 16(2): 97-102.
Abstract PDF(163KB) icon12142 icon2155
Abstract:
This paper reviews the aeroengine control technology in the late 20th century and focuses on the prospects of aeroengine control development in the early time of the 21st century.The main research and development of the aeroengine control will be placed on digital,integrated,distributed,optical fiber,multivariable,fault tolerant and intelligent controls.The benefits of the above technologies will be enhancing performances (thrust or power) and reliability, reducing weight and fuel consume.Some suggestions are proposed for the research and development of the aeroengine control in our country.
Technical Approaches to Thrust-Weight Ratio 12～15 of Aeroengine
JIANG Yi jun
2001, 16(2): 103-107.
Abstract PDF(769KB) icon1879 icon489
Abstract:
Based on the statistics of aeroengine database and a great number of computational researches,the technical approarches to increasing engine thrust weight ratio are considered.Due to aerodynamic and thermodynamic progress, such as increasing T 4 and component's efficiencies and decreasing turbine cooling air with the help of adequate materials and advanced technology,engine thrust weight ratio may reach 12～13.By means of improving the design techniques of engine parts,such as decreasing stage number of compressor,based on applying blisk and high paththrough design,the engine thrust weight ratio can rise up to 14.It may be 15 only based on metal and nonmetal composites with high strength and low specific weight.
Prospects of Aeroengine Power Transmission System in the 21st Century
LIN Ji shu, CHANG Zhen bo
2001, 16(2): 108-114,118.
Abstract PDF(1137KB) icon3529 icon757
Abstract:
In the early time of the 21st century the power transmission system of aeroengine still will be based on mechanical transmission,and will face the challenges of advanced aeroengine in respect to mainshaft bearing,lubricating,gear transmission and sealing.The researches on the electro magnetic bearings and the electro driving accessories,which will be used on future aeroengines,are just unfolded.This paper also introduces the development work and targets of the key laboratory of aeroengine power transmission in brief.
An Investigation of Matching between Dump Diffuser and Flame Tube
HE Xiao min, TAN Hao yuan
2001, 16(2): 115-118.
Abstract PDF(229KB) icon1693 icon490
Abstract:
An experimental investigation has been carried out to reveal the variations of total pressure loss and static pressure recovery with the inner and outer dump angles and the distance between prediffuser exit and the head of the flame tube (i.e.dump gap) at inlet Ma =0 265.The system comprised a straight walled prediffuser,a simple flame tube,five different inner and outer dump angles and four different dump gaps.
Characteristics of Helicopter Inlet with Front Output Shaft at Yawed Flight
HAN Dong, GUO Rong wei, WAN Da wei
2001, 16(2): 119-122.
Abstract PDF(240KB) icon1801 icon430
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An experimental study of the flow in a helicopter inlet with front output shaft was completed in low speed wind tunnel.The flow characteristics of the inlet in the flight envelope,in particular at yaw angles from 0° to 135°were investigated.The static pressure distributions along the duct,distortions of the flow field at the inlet exit section and total pressure recovery coefficients had been measured and analyzed.The results show that total pressure recovery coefficient of this type inlet is increased in every yawed flight,and are less related to the yaw angle.But the regions of local flow separation and distortion factor of the flow at the exit section are relevant closely to the yaw angle.Moreover,the characteristics of the flow at the exit section is the best at yaw angle equal to 90 degree,but these characteristics will deteriorate abruptly as the yaw angle is more than 90 degree.
An Investigation of Distortion Simulator for Inlet Flow Field
YU An yuan, WANG Qin fang
2001, 16(2): 123-127.
Abstract PDF(978KB) icon1764 icon523
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A new technique of distortion simulation for inlet flow was put forward.A device designed by using this technique includes a tablet simulator and a turbulence generator.The former consists of two thin tablets which can change the uneven total pressure of the flow to simulate steady distortion.The latter is a changeable turbulence ring,which can generate the turbulence of the flow.The experimental investigation of the device reveals some variation rules of aerodynamic characteristics obtained by selecting geometric parameters and combination of the tablet simulator and the turbulence ring.It is of benefit to designing distortion device of the inlet flow field for inlet/engine compatibility.
Computation of Flow around Isolated Airfoils with Embedded H-Grid
ZHANG Mou jin, Wong C M
2001, 16(2): 128-130,127.
Abstract PDF(252KB) icon1808 icon413
Abstract:
An embedded H grid technique is employed for generating grids of isolated airfoils and cascades.Comparing with original H grid,the embedded H grid is easy to control the orthogonality of grids around the leading and trailing edges of airfoils and useful to improving the accuracy of computation.Two numerical analyses of isolated airfoils under different incidences show that the results of computation using the embedded H grid are in good agreement with experimental data.
A Monotonicity Limiter Algorithm on Unstructured Grids for Computation of Nozzle Fields
YIN He, CHANG Li na, YAN Chuan jun
2001, 16(2): 131-134.
Abstract PDF(518KB) icon2010 icon496
Abstract:
A new monotonicity limiter algorithm is presented,particularly suited for unstructured grid applications,so as to constrain the interpolated values on either side of the interface by imposing a monotonicity coefficient on the gradient of each cell.The coefficient depends not only on the local gradient value but also on the gradient values of the surrounding cells,so that the solutions obtained be devoid of the oscillation.Numerical computations of the nozzle flows have been carried out.The results show that in conjuction with the limiter,the second order Godunov scheme produces good resolution of shock.
Experimental Investigation of Flow Fields in a Turbine Cascade with Endwall Film-Cooling Upstream of Leading Edge
LIU Gao wen, LIU Song ling, XU Du chun, Lapworth B L, Forest A E
2001, 16(2): 135-141.
Abstract PDF(928KB) icon2182 icon426
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Aerodynamic measurements,thermal tracing and surface flow visualization were carried out in a large scale low speed turbine cascade with single and double row injection on the endwall upstream of the leading edge.The detailed flow fields in the cascade,spacial distribution of cooling air and flow patterns on the endwall with coolant injection at blowing ratio 1～3 were obtained.In conjunction with the previously measured flow fields without cooling injection,the obtained results reveal that the flow fields in the cascade are obviously changed by endwall film cooling,and blowing ratio is a vital factor dominating the behavior of the injected coolant and secondary flow in the passage.It was also shown that the interaction between the two rows of injection makes the coolant air press closer to the endwall than with single row injection.The coolant injected at low blowing ratio could not reach the pressure side and was rolled up by the secondary flow.Medium blowing ratio injection can suppress the secondary flow effectively and tends to turn the endwall streamlines toward the inviscid streamlines and make perfect coverage of coolant on the endwall.The injection at high blowing ratio can throw the coolant onto the pressure surface,and even reverse the secondary flow and create a passage vortex with the rotation sense contrary to that of the traditional passage vortex in case of double row injection.
Inlet Distortion Effects in a Five-Stage Compressor
HU Jun
2001, 16(2): 142-146.
Abstract PDF(312KB) icon1952 icon450
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The inlet flow distortion effects in a five stage compressor have been investigated experimentally.The inlet total pressure distortion and swirl distortion have been generated by inserting perforated screens and guide vanes respectively into the compressor inlet duct.It has been found that both inlet total pressure distortion and swirl distortion have strong effects on the performance and stability of the compressor.With the increase in the angular width of the low inlet total pressure,both the pressure ratio and efficiency of the compressor decrease, and the loss of surge pressure ratio of the compressor increases when the distorted sector angle less than 60°.The inlet swirl distortion has a stronger effect on the loss of surge pressure ratio than the influence of inlet total pressure distortion.
Preliminary PIV Measurement of Unsteady Tip Flow in a Transonic Fan Rotor
LIU Bao jie, YAN Ming, LIU Yin, WANG Tongqing
2001, 16(2): 147-152.
Abstract PDF(801KB) icon1729 icon467
Abstract:
The digital PIV (Particle Image Velocimetry) is a powerful tool for investigation of complex unsteady flow in turbomachinery,but some special image processing techniques should be added to eliminate the influence of thick arcuate access window and very large pollutant particles on it.On the high speed compressor facility,the unsteady flow fields in a high load transonic fan rotor were measured successfully at the speed of 13200 r/min and 16800 r/min,and the instantaneous measurement results clearly show that:it is the tip clearance flow that causes the highly unsteady flow field in rotor tip region;the tip leakage flow is oscillating at all directions,and the interface between the tip leakage flow and the main flow is highly irregular at any instant.The unsteady movement of the tip leakage flow is the essential factor that causes high turbulence intensity in tip region.The tip leakage flow is a kind of high intense vortex flow,which can accelerate the main flow near the vortex core.Besides this effect,highly irregular interface between the tip leakage flow and main flow will also cause some high speed regions around the tip leakage flow.In the 80% corrected speed,these high speed regions become local supersonic,which will cause extra losses.
3-D Viscid Flow Numerical Research of Improving Aeroengine Performance with Twisted and Bowed Turbine Guide Blades
ZHENG Yan, YUAN Ning, WANG Zhong qi
2001, 16(2): 153-157.
Abstract PDF(407KB) icon1535 icon485
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A spacial twisted and bowed turbine guide blade was designed to improve the aeroengine performance.In order to maintain the design point of compressor,total temperature,total pressure and mass flow before the guide blade,and total pressure of turbine outlet is raised by using spacial twisted and bowed guide blade,so that the thrust may be improved by reducing the nozzle throat area.The characteristics of original turbine and the turbine with twisted and bowed guide blades were numerically simulated and analysed.The results demonstrate that the design concept and method are reasonable and useful.
Experimental Investigation on Flow Field between Two Fans of Contra-Rotating Fan Unit
ZHU Wei, LI Qiu shi, FAN Hong tao, LU Ya jun
2001, 16(2): 158-162.
Abstract PDF(704KB) icon1578 icon475
Abstract:
An experimental investigation was completed for studying the flow field between two contra rotating fans.A five hole probe was employed to measure the velocity field and pressure field between the two fans in case of varying their rotating speeds and the axial gap between them.The results of this study show: the work distribution between their rotor blades plays an important role in aerodynamic design of contra rotating fan and can be achieved through matching of their rotating speeds.Control design of the axial gap is also important for aerodynamic design of contra rotating fans.
A Study on Torsional Vibrations in an Encased Differential Gear Train
SUN Zhi min, SHEN Yun wen, LI Su you
2001, 16(2): 163-166.
Abstract PDF(787KB) icon1695 icon506
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A torsional vibration model formulated by time varying mesh stiffness and composite gear errors was established to predict the dynamic characteristics of the encased differential gear train.The mesh phases of the planet and star gears,elastic deformation and load inertia of planet carrier were also taken into account.A numerical method was applied to solving the large parametrically excited dynamic system.From the numerical results it was concluded that the gear meshing forces of the planetary gear train mainly fluctuated in meshing frequency of the planetary gear train;but the gear meshing forces of the star gear train fluctuated not only at the meshing frequency of the planetary gear train but also at that of the star gear train.A maximal dynamic load occurred at the high frequency resonance.The dynamic load factor of the planetary gear train was larger than that of the star gear train in the work speed area.
Effect of Chamber Pressurization on Crack Combustion and Propagation in Solid Propellant
YUAN Wei lan, SHEN Wei
2001, 16(2): 167-170.
Abstract PDF(644KB) icon2057 icon460
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A theoretical model describing the process of the crack combustion and propagation in solid propellant was formulated.The effect of chamber pressurization on the combustion and propagation of crack was studied by testing and computation researches on the model.The results indicate that the chamber pressurization has strong effects on the convective burning in the crack,crack initiation and fracture patterns.The higher the chamber pressurization is,the greater the velocity of the burning gas flowing into the crack,the higher the pressure in the crack,and the sooner the crack fractures.The calculated results are in good agreement with experimental data,that validates the reasonableness of the theoretical model.
The Finite Element Method for Solving K factor of TBC Interfacial Crack
LIU Liu, YANG Xiaoguang, GEN Rui
2001, 16(2): 171-174.
Abstract PDF(269KB) icon2019 icon507
Abstract:
Thermal barrier coatings (TBCs) provide thermal insulation to high temperature superalloys.However,the interfacial crack caused by thermal loading at the bond coat/TBC is a fatal factor for TBC spallation and failure.The effects of voids or crack like flaw at the interface can be responsible for initiating debonding and accelerating the oxidation process.The effect of interfacial cracks should be studied by using the fracture mechanics approach.Due to different properties of bond and top coatings,stress intensity factor is complex.The paper presents two methods to evaluate the K factor by using numerical results of finite element method.One utilized crack flank displacement data,and another utilized the J integral.A plate with edge crack under thermal loading and tensile loading is chosen as an example to calculate the stress intensity factors.The variation of the properties as a function of temperature was used for the analysis.Both methods show consistent results,but the J integral method can not obtain the phase angle,whereas the other method uses the crack flank displacement data.The results of the experiments or other numerical methods can also be used for K evaluation.
Damping Characteristics of Thin Metal Rubber Damper for Aeroengine Piping System
CHEN Yan qiu, ZHU Zi gen
2001, 16(2): 175-178.
Abstract PDF(722KB) icon1445 icon465
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Metal rubber (MR) is a kind of nonlinear material of high damping ratio,and has been widely used in aircraft and spacecraft because of its marked damper characteristics.Several experimental investigations on basic performance of thin and small size MR damper has been carried out.We designed a one DOF system,and thoroughly researched the influence of MR dampers with difference parameters on the performance of the designed system.The results indicated that the formation density and thickness,the mounting tightness,the metal wire materials of MR have different effects on the damping capacity of MR.The higher the exciting force,the better the damping effectiveness.In working process,MR shows the soft behaviour,so the vibration,especially the intensive vibration,can be suppressed greatly,provided the construction parameters of MR are properly selected.
Application of SQP to Multi-Object Optimization of Turbofan Engine Acceleration Control
HE Li ming, FAN Ding
2001, 16(2): 179-181,178.
Abstract PDF(644KB) icon1643 icon447
Abstract:
The control of aircraft engine acceleration is the focus in the field of aeroengine control.Sequential Quadratic Programming(SQP)based on nonlinear programming is used to control turbofan engine acceleration.Meanwhile the Linear Weighted Sum of multi object optimization has been introduced to attain double variable control in turbofan engine acceleration process.In the study every constraint of the acceleration process has been thoroughly considered.The simulation results show that the application of multi object optimization to turbofan engine acceleration control is feasible.It can bring the engine potentialities into full play and improve the acceleration performance significantly.
Study on CAD Method for Aeroengine Pipeline System
CHEN Zhi ying, TANG Wen zhe
2001, 16(2): 182-184,188.
Abstract PDF(558KB) icon1801 icon502
Abstract:
This paper summarizes nine principles of CAD aeroengine pipe routing and considers three approaches of CAD pipe routing.According to the complexity of aeroengine pipeline system and the features of computer aided routing,WRS(Wide in diameter,Region,Stride) approach is provided,that is first to route tubes Wide in diameter,then in dividing Region,last tubes of Striding regions.The approach conforms to rules of routing from wide in diameter to narrow,from short in length to long,from difficult in layout to easy.It bases on the principle that optimization in local region can reach to overall optimization of pipeline system.Considering the feature of 3D view for computer aided pipe routing,the WRS method avoids exchanging between the overall view and local view in the electronic engine mockup ,especially routing in dividing region.A pipeline system layout was successfully made on an electronic mockup by using the WRS approach.It is proven that the WRS method can gain success for only once,and shorten the period of design.The presented method is useful to aeroengine pipeline system design.
Measurement and Investigation on Thrust of Two-Phase Pulse Detonation Engine Model
FAN Wei, YAN Chuan jun, DENG Jun xiang, HUANG Xi qiao, ZHANG Qun
2001, 16(2): 185-188.
Abstract PDF(555KB) icon1761 icon494
Abstract:
The instantaneous thrusts of a two phase (gasoline/air) pulse detonation engine (PDE) model under various operational conditions were obtained from indirect measurement with a piezoelectrical accelerometer,and then the corresponding average thrusts were derived.The results reveal that this model can produce appreciable instantaneous thrust in the case of the small size detonation chamber,but the average thrust is very small due to low feeding rate in the experiment system.From the detailed investigation some approaches to enhancing the average thrust of PDE were found out.
A Test System for Mini Aviation Power Unit
ZHANG Tian hong, HUANG Xiang hua
2001, 16(2): 189-192.
Abstract PDF(306KB) icon1657 icon450
Abstract:
The mini power unit with diesel and propeller is widely used in aviation model,unmanned scout and target drone.A mini power unit test system is urgently required.In consequence a test and control system was designed for a power unit test bed,which has the advantages of being convenient and practical.All kinds of running status can be tested with this test bed,real time sampled data are logged for analyzing and displaying in graphic mode.The running parameters such as propulsion force,torque,rotation speed,cylinder temperature,exhaust gas temperature,throttle position,power and fuel flow are easily obtained in the course of experiments.Safety warning and emergency protection are also provided during the testing.Emulation of the running can be done with the test data and recorded audio.The hardware design,software development and applications of the system are described in detail.

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