In order to deeply understand the influence of rotor icing, the characteristics of rotor icing and its main corresponding factors were described from icing intensity and icing shedding from the tip part. Then the aerodynamic influences of icing on helicopter lift resistance, hovering and control characteristics were summarized, and the probable ideas of evaluating rotor ice shedding on helicopter physical damage were proposed. Main technologies in the application of rotor anti-/de-icing, such as electrothermal anti/de-icing, fluids anti-icing and pneumatic de-icing, were introduced, and their advantages and disadvantages were systematically analyzed. Concretely, electrothermal anti-/de-icing had high efficiency, but high energy consumption. Liquids anti-icing had low energy consumption, but short functional time and low anti-icing efficiency. Although the pneumatic de-icing system had low energy consumption, its installation position was limited, making it easy to cause aerodynamic losses of helicopters. On this basis, focus was put on the shortcomings of the current helicopter anti-/de-icing system, the important problems to be solved in the future development of anti-/de-icing were comprehensively prospected from the aspects of high-precision prediction of rotor icing, coupling development of various icing systems, and large-area preparation of super hydrophobic materials.

To investigate the film cooling characteristics of compound angle holes on turbine vane under high-speed conditions, a row of compound angle holes were set up on the suction surface of the turbine vane. The film cooling effectiveness and heat transfer coefficient ratio of the compound angle holes were measured. And the net gain of film cooling was measured by net heat flux reduction (NHFR). The effects of Reynolds number, blowing ratio and turbulence intensity on the film cooling effectiveness, heat transfer coefficient ratio and net heat flux reduction were analyzed. It was found that the film cooling effectiveness was affected by the Reynolds number, but when Reynolds number was larger than 6.4×10⁵, the film cooling effectiveness almost didn’t change with Reynolds number any more. When the turbulence intensity increased, the film cooling effectiveness decreased, making it more sensitive to the turbulence intensity at a low blowing ratio. The heat transfer coefficient ratio increased with the blowing ratio, but its sensitivity decreased under higher turbulence intensity. When the turbulence intensity increased, NHFR also increased. In general, at the blowing ratio is 0.8, the compound angle hole presents the best film cooling performance at a higher turbulence intensity.

In order to study the typical fire in the engine compartment, the large eddy simulation technology was used to establish a spray fire model of engine core compartment. The fire and fire propagation process in cabin was studied, and the effects of different leak positions and spray orientations on flame propagation, temperature and heat flux distribution were analyzed. The result showed that the spray leakage led to ignition and stable burning in the ventilated heat environment of cabin. There was a certain incubation period during ignition, after getting a high intensive and serious destructive fire. Spray fire indicated a typical incomplete combustion process controlled by ventilation, presenting a certain law of propagation; the center of the flame was located in the high-speed recirculation zone, and it spread rapidly to the air intake and tail exhaust. Different leak positions and spray orientations had a certain impact on fire propagation, temperature distribution and heat flux. The location of the leak had greater influence on the peak temperature and heat flux, and the spray orientation had greater influence on temperature and heat flux distribution.

To study the conjugate heat transfer characteristics of a free liquid jet impinging on a uniformly heated high-speed rotating disk, the effects of solid and fluid material parameters on the flow and heat transfer were analyzed by numerical simulation. The results showed that the local Nusselt number distribution corresponding to different solid material parameters was similar, and the maximum relative deviation of the Nusselt number at the same radius position was not more than 10%. Compared with the radial temperature distribution, the axial temperature difference was more affected by the change in the thermal conductivity of the solid material. The maximum radial temperature difference between copper and foam brick was only 3 times, while the difference between the maximum axial temperature difference approximately inverse to the thermal conductivity was 3471 times. The average radial velocity and heat transfer performance of liquid film on the disk surface decreased with the increase of fluid viscosity. The secondary peak heat transfer intensity corresponding to ammonia and water with less viscosity increased by more than 15% compared with the primary peak, and the secondary peak heat transfer intensity of lubricant oil with higher viscosity was only 50%—60% of the primary peak. When water and ammonia were used as the jet medium, the surface temperature of the disk remained almost constant, and the maximum temperature difference ratio was less than 7.86×10^-4. When the lubricant oil was used as the jet medium, the temperature near the stagnation point changed drastically. In the region with R/d exceeding 2.5, the temperature distribution only fluctuated slightly.

In order to obtain the characteristics of spray field of main stage nozzle and pilot nozzle of central staged combustor at idle condition, the particle image velocimetry (PIV) was used to measure the spray field of single-tube combustion chamber with different head schemes and different nozzle fuel ratios. And the post-processing software of spray field image was developed, the spatial distribution of the spray field was obtained by extracting oil droplets on raw pictures in the central graded combustion chamber. The research of spray field under idle condition indicated that: large-size droplets were distributed in a conical shape in the fuel-rich head area of the combustion chamber, while the Sauter mean diameter (SMD) was distributed in a V-shaped radial direction, namely, small in the middle and large on both sides. The reduction of the expansion angle of the baffle made the number of droplets concentrated in the fuel-rich head area of the combustion chamber and the average SMD was larger. When the incoming flow conditions and the fuel-air ratio were kept constant, changing the fuel ratio had little effect on the atomization effect. The particle size with the largest number of droplets in the spray field under idle conditions was 25 μm, and the particle size range with the largest volume ratio was 30−50 μm.

The Reynolds-averaged Navier-Stokes (RANS) equation is still widely used in engineering design due to its low computational cost. In order to further improve the calculation accuracy and reduce the time, a deep neural network (deep neural networks, DNN) method was applied to adaptively identify the steady-state turbulent eddy viscosity coefficient. Taking the detection flow field generated at the front edge of the shock train in the isolation section as an example, the Wilcox-2006 $k$-$ \omega $ turbulence model was used for simulation. A steady-state turbulent eddy-viscous flow field was generated as a training dataset for model learning under different back pressure conditions. Finally, tests were carried out under different back pressure conditions. The results showed that the proposed DNN method can quickly predict the value of the turbulent eddy viscosity coefficient. The coefficient of determination was greater than 99%, and the predicted flow field results were basically consistent with the real flow field, which further verified the feasibility of deep learning technology in turbulence model parameter identification.

With the background of transpiration cooling technology, the influence of porous media structure on structure temperature field was investigated at pore scale by using D3Q19 lattice Boltzmann method program. The permeability and solid temperature distributions of two commonly used porous structures: spherical particle packing structure and random structure, were simulated and analyzed respectively. The results showed that for the particle packing structure, when the particles were arranged regularly, the solid temperature distribution showed an obvious ladder shape; when the particles were arranged irregularly, the solid temperature change trend was relatively stable, and with the increase of particle diameter, the permeability increased and the solid temperature decreased. For random porous structure, with the decrease of pore size, permeability decreased and solid temperature increased. In the porosity range of 0.3—0.5, due to the different internal convection heat transfer intensity of particle packing structure and random structure, the solid temperature had different variation characteristics.

Film cooling characteristics and loss mechanism of double-jet hole and contracted double-jet hole with blowing ratio varying from 0.5 to 2.0 were numerically simulated. Results showed that the lateral film coverage developed and the film cooling effectiveness was promoted for the Contracted Double-jet hole when the blowing ratio was bigger than 1.0. When the blowing ratio reached 2.0, the Contracted Double-jet hole can prevent the film lift-off. Compared with the Double-jet hole, the cooling flow at the inlet of the Contracted Double-jet hole was accelerated evenly and the blockage caused by the low velocity zone in the hole was eliminated so that the flow field became uniform and the total pressure loss was reduced.

To study the interaction between shock wave and supersonic film, a model of supersonic plate film cooling with discrete hole was simulated. A wedge was introduced into the mainstream to create shock wave environment. Coupled heat transfer of supersonic film and high temperature wall was studied under four different shock wave intensities, in which wedge angle was 0°, 15°, 20° and 25° respectively. The simulation result showed that the appropriate intensity of shock wave can effectively eliminate the reverse vortex pairs generated with film injection into mainstream, restrain the entrainment of film, increase the average mole fraction of H₂ and also reduce the wall temperature. The analysis of metal temperature field showed that the wall cooling effectiveness first increased and then decreased with the increase of the shock wave angle. The flow field structure with wedge angle of 20° was the most effective to wall temperature protection among all cases. In addition, the cooling effect of coolant at low Mach number could be more easily improved by a smaller wedge angle, whereas the situation was opposite for bigger wedge angles. The results showed that these trends couldn’t be influenced by thermal barrier coating (TBC). The presence of shock waves weakened the scope of TBC’s influence. For revealing the heat transfer mechanism of supersonic film under coupled heat transfer conditions, this method helps to provide a reference for the design of supersonic film cooling, or to provide a basis for the optimization of existing supersonic film cooling structure.

In order to study the influence of rotating speed variation on the performance and vibratory load of rotor, a scaled hingeless rigid rotor was developed. The dynamic scaled and Mach number scaled hover test and wind tunnel test were carried out. Rotor trim, performance, blade and pitch link loads, hub loads and some other aspects were studied by changing the thrust, airspeed and rotating speed. The credibility of the test results was proved by the repeatability and periodicity of the performance and the vibratory load. Results indicated that the power required can be saved by reducing the rotor speed for both hover and forward flight, and lower thrust showed higher effectiveness. The amplitude of vibratory hub load was not obviously increased by reducing rotor speed. The frequency of rotor rotating speed vibratory blade load and pitch link load increased, because the cyclic pitches were greater in trimmed condition for slower speed, which was adverse to the fatigue life of the rotating parts. Natural frequencies of the rotating blade should be avoided for varying the rotor speed to prevent enlargement of the vibratory load caused by the resonance.

In order to reduce the risk of test model and gauge balance damages induced by shock impingement during intermittent supersonic wind tunnel startup and shutdown, an impingement attenuation device was designed. Composed of upper/lower actuating facilities and flat plates, the four-part connecting rod device was analyzed by finite element method, validating the strength and stiffness of device structures. Servo control system and accompanying software were developed, and the control parameters were determined according to structural dynamics analysis. A working procedure compatible with the wind tunnel was devised, and visualized software interface was customized. The device effectiveness was tested from structural steadiness and attenuation effect. Test results indicated that the device had a favorable effect on impingement attenuation for the normal force and pitching moment, with a decrease of amplitude up to 78% and 77% separately.

In order to reduce the convergence requirements for solving the nonlinear model of aeroengine, the problem of solving the model nonlinear equations was transformed into the least square problem. A hybrid algorithm based on Levenberg-Marquardt (L-M) algorithm was proposed. The hybrid algorithm avoided the local solution by modifying the local solution with dynamic method. Meanwhile, Broyden quasi-Newton method was used to accelerate the L-M algorithm. Targeting turbofan engine, the hybrid algorithm, L-M algorithm, Newton method and Broyden quasi-Newton method were used for steady-state and transient simulation. Results showed that: under the steady-state condition, if L-M algorithm and hybrid algorithm had larger convergence range, the convergence rate can reach more than 90% under the random initial value condition, much higher than the convergence rate of Newton method and Broyden quasi-Newton method which was less than 20%, and the calculation speed of hybrid algorithm was similar to that of Broyden quasi-Newton method. Under transient condition, L-M algorithm and hybrid algorithm can converge at strong transient condition where neither Newton method nor Broyden quasi-Newton method converged, and the transient computation time of hybrid algorithm was only 1.13 times that of Broyden quasi-Newton method. Simulation results show that the algorithm has good applicability in solving aero-engine model solving.

In order to address the problem of the unsteady aerodynamic mutual interference of propeller/wing system in cases of complex asymmetrical inflow, the hybrid structured-unstructured sliding mesh method combined with the unsteady Reynolds-averaged Navier-Stokes equation was used. This approach assessed the influences of yawed angel and inflow conditions (e.g., angle of attack and freestream velocity) on mutual aerodynamic interference of the propeller/wing and the propeller slipstream, and compared with the calculation results of the no-slipstream model. The results revealed that under the influence of three-dimensional asymmetric inflow, the wing lift coefficient and drag coefficient fell by 4.9% and 10.64%, respectively, when the yawed angle increased from 0° to 20°. However, the thrust coefficient and propulsion efficiency of the propeller improved significantly by 18.36% and 7.26%. Additionally, the fluctuation range of the lift coefficient of the asymmetrical inflow was four times that of the symmetrical inflow condition. When the angle of attack remained constant and the yawed angle changed, the propeller slipstream enhanced the stability margin of the wing pitching moment. Unfortunately, with a fluctuating angle of attack, the longitudinal instability of the wing gradually increased. Meanwhile, under the influence of the airflow behind the propeller disk, the suction peaks on the upper surface of the wing on both sides of the nacelle moved leftward and forward, while the absolute values of the peak on both the upper and lower surfaces increased considerably. With varying wing speed, the increase in wing lift performance with slipstream was around 20%, compared with the wing without the influence of slipstream. Besides, the lift performance continued to increase with wind speed.

The sound source localization algorithm using incomplete microphone arrays was studied, and the sound source localization algorithm was obtained through interpolation compensation of the cross spectral matrix of the incomplete microphone array by modified Fourier interpolation, B-spline interpolation and cubic spline interpolation. The sound source localization algorithm was verified by numerical simulation, and it was found that the maximum deviation of the Fourier interpolation simulation result was 5.21 dB, the B-spline interpolation was 1.17 dB, and the cubic spline interpolation was 0.80 dB on the beamforming sound source intensity; in the sound source position deviation, the Fourier interpolation value was 0.04 m, the B-spline interpolation value was 0.01 m, and the cubic spline interpolation value was 0.01 m. The results showed that the intensity, position accuracy and dynamic performance of the sound source localization calculated by Fourier interpolation were the worst, the cubic spline interpolation was the best, and the B-spline interpolation had the average performance. Experimental verification has also reached a similar conclusion, so it is best to use cubic spline interpolation to calculate the cross spectral matrix of an incomplete microphone array.

For the dynamic tilting model of the vertical/short takeoff and landing (V/STOL) aircrafts during the transition process, a deep insight into the optimal control strategy was gained by considering the constraints of the conversion corridor, control redundancy and the demand indexes of different take-off/landing missions. Considering the jet-induced effect of the prototype aircraft, the V/STOL aircraft was totally modeled. A calculation architecture for the general conversion corridor was established based on the attainable balance set methodology. A control strategy was designed to ensure smooth conversion from the V/STOL aircraft transition process to the high-speed forward flight phase. By converting the dynamic tilting problem during the transition process to a dynamic nonlinear optimal control problem, the appropriate indexes and constraints were established according to the characteristics of different take-off/landing missions. The method of calculating the conversion corridor by reachable equilibrium set was not limited by the type of aircraft, but also was used to simplify the construction process with good versatility and robustness. The optimization results with the goal of smooth transition grealy reduced the pilot’s manipulation change during the aircraft transition process, so that the pilot can focus more on the manipulation of the aircraft motion. The optimization result for shorter distance shortened the flight distance of landing process by about 30%. The optimization results from the control strategy enabled the pilot to better grasp the control focus and boundary, and increased the safety of the entire dynamic transition process.

There are still many problems in load identification of non-stationary signals of full-size model test in wind tunnel test. A full scale model test of non-stationary signal load identification was proposed based on a deep residual shrinkage network （DRSN） deep learning technology of intelligent load identification method. This method extracted load system output data of aerodynamic force and inertial force and noise characteristics by deep learning, through attention mechanism it obtained data access threshold for each group, then the soft threshold function was used to filter the characteristics and reduce the noise. The inertial force component in the response signal of the force measurement system was identified and eliminated effectively, so as to realize the identification of aerodynamic load. In the test and verification, the identification accuracy of the mean value method was above 85%, and that of the DRSN model was above 94%, proving that the DRSN model can effectively reduce the interference of noise and inertia force on the load identification. It presented the characteristics of high accuracy and good reliability for the load identification of non-stationary signals.

For the purpose of technological progress for ceramic matrix composites (CMCs) turbine blade design in advanced aero-engines, based on main performance parameters of typical turbofan engine, and according to the forward turbine blade design process, a conceptual design method was established from aerodynamic design to structural design finally to deformation and strength analysis, and a CMCs low pressure turbine rotor blade was designed, which was solid without cooling. In the conceptual design method, strength was taken as the major constraint, aero-engine thrust and specific fuel consumption taken as inputs, and model of turbine blade body taken as output. The simulation results indicated that aerodynamic performance, strength and vibration performance of the designed blade under design conditions satisfy the design requirements. Reserve factor of safety reached 1.8 and the external load level of the turbine disk was estimated to be reduced by 50%, proving the feasible application of CMCs on advanced aero-engines. Turbine efficiency increased approximately 0.98%—1.17%, which demonstrated the potential of CMCs to promote the performance of high-temperature components in advanced aero-engines.

Intelligent aero-engines damage detection is an important research direction in aircraft fault diagnosis. An improved multi-scale target detection method based on You Only Look Once version 4 (YOLOv4) was proposed for the problem that existing target detection model has a poor effect on the detection of small target damage of aero-engine. A new shallow feature fusion layer was constructed in path aggregation network （PANet）, which fused shallower features with deep features to improve the network detection performance for small target damage. In order to reduce redundant parameters in the network, depthwise separable convolution was introduced in neck and the standard convolution was reconstructed into the form of depthwise separable convolution. Experiments showed that the improved YOLOv4 improved the detection accuracy of small target damage by 3.43%, reduced the model size by 54.06 MB, and increased the detection speed of the model by 31.03%. The results of the study indicated that the improved YOLOv4 model had better detection performance for small target damage.

In order to study the bolt looseness characteristics, a fine finite element model of bolt connection structure with raised angle was established, and the initial preload was applied by means of applying torque method. Then, simulation analysis of bolt looseness characteristics was carried out, Finally, the accuracy of this method was verified. The results showed that: the change law of slip adhesion contact state of bolt head contact surface and thread contact surface can accurately characterize the bolt loosening characteristics; the alternate change of slip adhesion contact state of two contact surfaces is the main factor causing bolt loosening; if there is always an adhesion area, no bolt loosening occurs; the larger area of contact surface in the sliding state indicated the faster growth rate, the faster bolt loosening and higher likeliness of loosening; the larger amplitude and the greater eccentricity distance indicated the larger area and the faster speed of two contact surfaces entering the sliding state, and the easier bolt loosening; the greater difference of friction coefficient between the two contact surfaces indicated the higher likeliness of bolt loosening.

For the dual-rotor system with mid turbine frame, the mechanical impedance theory was used to quantify the structural mass/stiffness distribution characteristics, and the vibration coupling mechanism model of complex rotor system was established, then the vibration coupling point determination and interactive excitation transient response simulation methods for shared support dual-rotor system were proposed. The simulation results showed that the mechanical essence of shared support dual-rotor system vibration coupling lied in the dynamic response coupling under the vibration interaction between rotor and support structure, including vibration coupling mechanical behavior caused by foundational vibration of shared support structure as well as interaction excitation of multiple rotors. Vibration coupling level under foundational excitation was related to support mechanical impedance and rotor mode shape, and the vibration coupling level under rotor interaction excitation was affected by excited rotor mode shape. The rigid body mode shape of excited rotor was sensitive to foundation vibration, making it easier to produce rotor interaction excitation vibration coupling under excitation of another rotor.

To study the influence of geometrical parameters of pocket on the wear performance of V-shaped pocket cage of cylindrical roller bearing under high rotational speed and light load conditions, a bearing dynamic model considering the influence of lubrication at pocket was established. Based on the time-averaged wear rate of Masjedi wear model, the influence of geometric parameters of pocket on the wear performance of V-shaped pocket cage was studied. In addition, the wear and slip performances of V-shaped pocket cage with 15° inclination angle at different rotational speeds were analyzed. The results showed that the geometrical parameters of the pocket had remarkable effect on the wear performance of the cage, and the wear performance of the cage can be effectively raised by optimizing the geometrical parameters of the pocket. The time-averaged wear rate of cage increased with the inner ring rotational speed. When the inner ring rotational speed ranged from 5000 r/min to 20000 r/min, the time-averaged wear rate and slip rate of V-shaped pocket cage with 15° inclination angle were lower than those of ordinary straight pocket bearings.

An elastic ring bearing damper with sinusoidal corrugated shape was designed, and also coupled with rolling bearing to realize the function of vibration absorption and energy absorption. The mechanical model of elastic waved ring damping bearing was established, and damping bearing was analyzed by finite element method. Influences of geometric parameters of elastic waved ring on the stress distribution, radial compression stiffness, vibration reduction, and energy absorption were studied. Results indicated that stress distribution of elastic waved ring was greatly improved compared with the stepped elastic convex ring. In a given working condition, the maximum Mises stress was decreased by 64% from 1 356 MPa to 464 MP as stress concentration phenomenon was eliminated. Thickness of elastic ring, wave period and diameter of elastic ring all had significant influences on the stress and stiffness. Elastic waved ring also greatly reduced the impact force of the bearing under vibration impact.

Based on the optimal Latin hypercube sampling, polynomial surrogate model, Fourier amplitude sensitivity test, and gradient mutation hybrid optimization algorithm, a coupling optimization method of transonic centrifugal compressors was constructed, and the goal of self-recirculation casing treatment stability improvement without loss of isentropic efficiency was achieved. After the coupling optimization, the aerodynamic performance of the compressor was comprehensively improved. The isentropic efficiency of the design point and near-stall point increased by 2.79% and 1.82%, respectively, and the peak efficiency was slightly higher than the solid compressor. According to the mechanisms of coupling optimization for stabilization and efficiency enhancement: the recirculation flow of self-recirculation casing treatment was increased, and more low-energy fluid was removed; the flow incidence angle of impeller was improved, and the risk of flow separation was reduced; the interaction of leading edge shock wave and the tip leakage vortex was suppressed, the low-energy fluid downstream the impeller was reduced, and the circumferential uniformity of the flow was enhanced; the injection angle of upstream slot of the casing treatment was increased, and the radial distortion of the impeller inlet was weakened; the increases of both the blade angle of the impeller trailing edge and the radius of the diffuser blade trailing edge made up for the isentropic efficiency loss; the reduction of the back sweep of the impeller blade leading edge made up for the choke flow.

In order to study the internal ballistic characteristics of the solid rocket motor（SRM） under dynamic lateral overload, the burning rate measurement of a three-component composite propellant under −50g−50g overload acceleration was carried out, and the overload burning rate model of the propellant was established by combining with the Greatrix multi-parameter model; based on this model, the combustion surface retreat of tubular inner hole combustion grain under lateral overload was carried out, and the internal ballistic calculation model of large aspect ratio SRM under dynamic lateral overload was established. Results showed that there was an angular threshold for the influence of overload on the burning rate, and the influence of negative angular overload was small; an instantaneous lateral overload made the combustion chamber pressure jump, under 100g overload, the pressure increased by about 8%, the overload disappeared and the pressure dropped suddenly; if the time interval of lateral overload was fixed, the pressure change amplitude of maneuvering flight after 100g overload （t=12−15 s） was 1% smaller than that of maneuvering flight first （t=3−6 s）, which was more favorable for flight.