Geometric modeling analysis method for stacking assembly deviation of aero engine rotor

A detailed unsteady numerical simulation has been carried out to investigate the shock systems in the high pressure (HP) turbine rotor and unsteady shock-wake interaction between coupled blade rows in a 1+1/2 counter-rotating turbine (VCRT). For the VCRT HP rotor, due to the convergent-divergent nozzle design, along almost all the span, fishtail shock systems appear after the trailing edge, where the pitch averaged relative Mach number is exceeding the value of 1.4 and up to 1.5 approximately (except the both endwalls). A group of pressure waves create from the suction surface after about 60% axial chord in the VCRT HP rotor, and those waves interact with the inner-extending shock (IES). IES first impinges on the next HP rotor suction surface and its echo wave is strong enough and cannot be neglected, then the echo wave interacts with the HP rotor wake. Strongly influenced by the HP rotor wake and LP rotor, the HP rotor outer-extending shock (OES) varies periodically when moving from one LP rotor leading edge to the next. In VCRT, the relative Mach numbers in front of IES and OES are not equal, and in front of IES, the maximum relative Mach number is more than 2.0, but in front of OES, the maximum relative Mach number is less than 1.9. Moreover, behind IES and OES, the flow is supersonic. Though the shocks are intensified in VCRT, the loss resulted in by the shocks is acceptable, and the HP rotor using convergent-divergent nozzle design can obtain major benefits.

In recent years, extensive research has been undertaken to improve the service properties of 1Cr-Mo-V steels with the aim of manufacturing high-pressure (HP) and medium-pressure (MP) turbine rotors having higher creep-rupture and toughness values. However, notched impact strength, fracture appearance transition temperature (FATT), and fracture toughness depend greatly on heat treatment. Oil quenching after austenitizing, which is common practice in Europe, gives higher values than air quenching, which is specified in the United States. A change in heat treatment, however, has little effect on the toughness in the core of turbine rotors. To improve this property, it is necessary to increase the alloy content of the steel. This has led to the development of a new 23Cr-Ni-Mo-W-V 8 8 steel for HP rotors. After testing this new steel at laboratory level, a 114-ton electroslag remelted (ESR) ingot was produced, from which a 42.5-ton turbine rotor with a 1370-mm maximum body diameter and a 1555-mm flange diameter was manufactured and extensively tested. Results obtained from transverse specimens showed an 0.2% yield strength of 650 N/mm2, excellent elongation, reduction of area, and notched impact strength values, as well as a FATT of 273 K (0°C) at the surface, 293 K (20°C) at midradius, and 313 K (40°C) in the core. A modified production process will give a FATT of 293 K (20°C) in the core of the turbine rotor with excellent creep-rupture properties.

This paper proposes a method for predicting concentricity and perpendicularity based on PSO-BP neural network in order to solve the problem of low accuracy for aero engine multistage rotors assembly. The influence factors of error propagation in the assembly are analyzed based on the characteristics of rotor structure and assembly process. And neural networks for predicting concentricity and perpendicularity of multistage rotors assembly are established. The particle swarm algorithm is used to optimize the hyperparameters of the neural network and the optimal hyperparameters can be obtained. In order to verify the effectiveness of the concentricity and perpendicularity prediction method proposed in this paper, experiments are carried out for four rotors assembly with precision rotary measuring instrument. The results show that for the 30 groups of testing samples, the average deviations of concentricity and perpendicularity by PSO-BP neural network prediction method are 1.0 μm and 0.6 μm, respectively. The prediction accuracy of concentricity and perpendicularity of final assembly are improved by 4.5 μm and 2.6 μm, respectively, compared with the traditional assembly method. The proposed method in this paper can be used not only for the guidance of multistage rotors assembly of aero engine, but also for the tolerance allocation in the design process.

Purge air is injected at the hub and shroud of axial turbines in order to avoid hot gas entering the gaps between stationary and rotating blade rows. The purge flows considerably interact with the main flow and influence the secondary flow like the tip leakage vortex. Therefore, at Graz University of Technology the flow in a product-representative one-and-a-half stage test turbine under the influence of purge flows was investigated. Four individual purge mass flows differing in flow rate, pressure, and temperature were injected through hub and tip cavities before and after the unshrouded high-pressure turbine rotor. In order to get more insight into the cavity flows and the flow evolution in the rotor this configuration is studied with a steady CFD simulation with and without purge flows. It was found that the secondary flow and especially the tip leakage vortex is significantly influenced by the purge flow which varies in circumferential direction. The differences between purge and zero-purge flow conditions are discussed with the help of radial distributions and contour plots of stream-wise vorticity. Streamlines allow to follow the path of the purge flows in the rotor and show the radial displacement of the secondary flow vortices. Wall streamlines describe the changes in the boundary layer flow and their effect on the vorticity after the trailing edge.

Aiming at the difficulty of both accuracy and computational efficiency in aero engine rotor model, a method of dimensionality reduction and modification of aero engine rotor model considering contact stiffness is proposed. First, a three-dimensional finite element model of the aero-engine rotor is established, using thin-layer elements to represent the end-tooth contact interface between rotor discs. Second, based on the Craig-Bampton fixed-interface modal synthesis method, a reduced model of the rotor is obtained, retaining the main nodes at the bearing and the end-tooth contact interface positions. Finally, the contact stiffness in the reduced rotor model is modified based on the sensitivity method and rotor modal testing. The maximum frequency error of the first three orders of bending mode frequencies calculated by the modified model is reduced from 12.84% to 0.11%, and the calculated modal shapes are consistent with the experimental results. Moreover, the average time of five iterations of correction calculation is 0.8 seconds on the platform of Matlab software, which verifies the accuracy and efficiency of the method. The calculation results show that the dimensionality reduction and modification method considering contact stiffness can not only satisfy the correction accuracy, but also significantly improve the model correction efficiency of aero engine rotor.

Bolted flange joints are used to connect adjacent disks and drums in aero-engine rotors. The flange mating contact surfaces usually move relative to each other and deform when they are subjected to numerous combinations of loads during normal operation. Consequently, the local bending stiffness of the bolted flange joint is altered considerably affecting the overall rotor stiffness and therefore the rotor dynamics. This paper presents a study on the effect of the bending stiffness of bolted flange joints on the dynamic characteristics of an aero-engine rotor. A method to calculate the bending stiffness is proposed using an equivalent model based on an axial spring and bending beam stiffnesses. The relationship of the structure geometry, loading and assembly conditions of the bolted flange joints, and the bending stiffness loss are obtained. Furthermore, a dynamic model of an aero-engine high-pressure compressor rotor is developed using the transfer matrix method that incorporates the bending stiffness effect of the bolted flange joint. Based on this model, the influence of bending stiffness on the natural frequency and the steady-state response is discussed. The results show that the stiffness loss of bolted flange joint has a significant impact on the rotor dynamics. The structure geometry, loading, and assembly conditions can be used to control the dynamic response of aero-engine rotors.

Innovative optimization methods that balance power efficiency, computational complexity, and performance are needed to meet IoT device demand for low-power, high-performance VLSI circuits. Combining quantum computing with traditional optimization methods is necessary due to the exponential development of circuit complexity. This study optimizes low-power VLSI circuits using a hybrid quantum-classical framework that uses quantum circuit optimization, quantum annealing, and hybrid variational methods. The framework reduces gate count, power consumption, and latency by combining quantum-assisted logic optimization with classical heuristics. Simulations and experiments prove the framework can improve energy-efficient hardware designs. Quantum gate reduction (QGR) and quantum state encoding (QSE) optimize Boolean logic, while quantum annealing refines transistor location and reduces leakage power. Classical post-processing methods like heuristic refinement and logic gate remapping fine-tune quantum-optimized circuits for practical application. Compared to classical approaches, the hybrid architecture reduces gate count by 35%, saves 28% power, and improves latency by 25%. Performance validation using IBM Quantum Experience and D-Wave devices shows that quantum-assisted VLSI optimization techniques are possible. Further research on fault-tolerant quantum computing, hybrid co-design, and real-world CMOS integration for next-generation semiconductor fabrication are planned. This study shows how quantum-classical hybrid techniques can alter electronic design automation.

This study investigates the effect of thermal barrier coatings (TBCs) on the temperature distribution throughout a first-stage high-pressure aero-engine gas turbine rotor blade. The temperature changes on the naked and TBC-coated blade surfaces were investigated using computational models in ANSYS. The results showed a considerable drop in maximum temperature after using yttum-stabilized zirconia (YSZ) as a TBC, demonstrating its efficiency in alleviating thermal stresses. A comparative investigation of various TBC materials revealed varying degrees of heat resistance, with those with lower thermal conductivities. YSZ brought down the maximum temperature of the blade body by 18%. Lanthanum zirconate (La2Zr2O7) showed the best results, bringing down the maximum temperature by 19.5% compared to YSZ. These findings highlight the need to evaluate material qualities other than heat resistance when selecting TBCs for aerospace applications. This study underlines TBCs’ potential to improve the durability and performance of gas turbine rotor blades under high-temperature operating conditions. Furthermore, it suggests future research directions, such as investigations into TBC mechanical properties, erosion resistance, and long-term durability of TBCs, as well as the development of novel TBC formulations and manufacturing techniques to advance aerospace technology and ensure the sustainability of gas turbine operations.

A computational study was performed to investigate deposition phenomena in a high-pressure turbine stator and rotor stage. Steady mixing-plane and unsteady sliding mesh calculations were utilized. 3D, steady and unsteady RANS calculations were performed in conjunction with published experiments completed on identical turbine geometry in order to extract boundary conditions and to validate flow solutions. Particles were introduced into the flow domain and deposition was predicted using a Lagrangian particle tracking method with the critical viscosity model to predict deposition. For the steady method, in order to track particles from the mixing plane through the blade domain, particle positions were saved after passing through the vane domain and inserted into the blade domain using two different methods: averaged and preserved. Both methods yielded nearly identical results. For the unsteady simulation particles were tracked through a sliding mesh interface with particle position, velocity, and temperature preserved at exit of the vane domain and inlet of the blade domain. Deposition results for the steady mixing plane using both particle averaging techniques and unsteady sliding interface were compared for particles of different sizes. Large particles produced localized impact and deposit zones near the hub and tip of the pressure surface for all methods. Steady methods overpredicted impacts and deposits relative to unsteady methods by averaging out discrete unsteady vane wake motion which caused particle motion towards blade surfaces.

Most of the current understanding of tip leakage flows has been derived from detailed cascade experiments. However, the cascade model is inherently approximate since it is difficult to simulate the boundary conditions present in a real machine, particularly the secondary flows convecting from the upstream stator row and the relative motion of the casing and blade. This problem is further complicated when considering the high pressure turbine rotors of aero engines, where the high Mach numbers must also be matched in order to correctly model the aerodynamics and heat transfer. More realistic tests can be performed on high-speed turbines, but the experimental fidelity and resolution achievable in such set-ups is limited. In order to examine the differences between cascade models and real-engine behavior, the influence of boundary conditions on the tip leakage flow in an unshrouded high pressure turbine rotor is investigated using RANS calculations. This study examines the influence of the rotor inlet condition and relative casing motion. A baseline calculation with a simplified inlet condition and no relative endwall motion exhibits similar behavior to cascade studies. Only minor changes to the leakage flow are induced by introducing either a more realistic inlet condition or relative casing motion. However when both of these conditions are applied simultaneously the pattern of leakage flow is very different, with ingestion of flow over much of the early suction surface. The paper explores the physical processes driving this change and the impact on leakage losses and modeling requirements.

Recent progress in precision measurement and assembly optimization methods of the aero-engine multistage rotor: A comprehensive review

Study the optimization of aero-engine PID (Proportional-Integral-Derivative) controller parameters. In order to improve the tuning accuracy on aero-engine PID control parameters for the optimal solution, this paper presents a genetic algorithm-based PID parameter tuning method. Because the choice of crossover and mutation probabilities in genetic algorithm have a significant impact on the convergence speed and stability of the control system, genetic algorithm is adopted of which the crossover and mutation probability can automatically change with the fitness. Simulation results show that after variable crossover and mutation probability adaptive genetic algorithm to optimize PID control parameters, the average convergence algebra is significantly reduced and the overall control performance of the system is better. Aero engine work process is complex systems that big lag, nonlinear and multi-coupling throughout the flight envelope, Aero engine aerodynamic thermodynamic processes will occur a very big change, with the change of environmental conditions and flight status (airspeed, Mach number, etc.), so be quick, effective control is particularly important. PID control is one of the earliest developed control strategy, due to its simple structure, robustness, high reliability, easy to implement and other characteristics, widely used in process control and motion control, especially in the determination system that precise mathematical model can be established. Three parameters of proportional coefficient ( Kp ), integral time ( Ki ) and derivative time ( Kd ) tuning are direct influenced the control effect of the PID controller, the optimizing of PID controller parameters directly affect the control effect of control system. At present, there are many ways to optimize the PID parameters, such as Ziegler-Nichols method, indirect optimization method, the gradient method, climbing method, etc. The designer of these methods, mainly through the Mathematical model of controlled object, combined with practical experience, through repeated on-site equipment debugging obtained. Because these tuning method are relatively complicated, and affected by human factors, the final parameters of being got are not usually the optimal solution. The traditional tuning method based on a specific model is not applicable, for such aero engine as complex nonlinear systems. Therefore you can take advantage of intelligent control technology for optimizing PID parameters in order to achieve optimal control. Genetic Algorithm (GA) is an optimization method for parallel simulation of natural genetic mechanisms and biological evolution and the formation of a random search, survival of the fittest principle of biological evolution exist in nature, was introduced to optimize the parameters of a coded series groups.

In this paper, the Taguchi optimization method is applied to obtain the optimal and robust design towards enhancement of board-level thermomechanical reliability of a package-on-package stacking assembly under an accelerated thermal cycling test condition. An L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sub> (2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> times3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> ) orthogonal array is arranged for the optimization of eight selected control factors of the assembly, including thickness of dies, molding compounds, and substrates, sizes of package and molding compound, and solder joint standoffs. The importance of each of these control factors is compared and ranked

Vibration analysis of a dual-rotor-bearing-double casing system with pedestal looseness and multi-stage turbine blade-casing rub

The coupling fluid flow-thermal model of natural convection heat in a High-Pressure Rotor (HPR) of the aero engine was established with Computational Fluid Dynamics (CFD) method. The temperature distributions and flow fields of the HPR with different shutdown time were studied. Then, the temperature distributions of the HPR during the hot start-up with different shutdown time were calculated. Moreover, the effects of hot start-up and shutdown temperature fields on the critical speeds of the HPR were carried out. The results show that the flow rule in the cavity of HPR is different from that in a quadrate cavity and presents diversity and complexity of flow. During 40-90 min of shutdown time, the temperature difference of the HPR is more than 20°C. When the shutdown time reaches to 60 min, the first critical speed of the HPR is decreased by 22.3% from 2256 to 1768 rpm.