Aero-engine Manufacturers Research Articles

Nonlinear effects of bolted flange connections in aeroengine casing assemblies

Aeroengine manufacturers face fundamental limitations when correlating experimental dynamic analysis with finite element method models. The source of inconsistency between model predictions and experimental test data can be attributed to nonlinear behaviour at the bolted flange interface. The two main sources of nonlinearities in aeroengine casing assemblies are damping dissipation and the nonlinear effects of boundary conditions. In this research, a novel and robust analytical formulation is proposed for implementation in FE analysis that accurately captures and represents the nonlinear dynamic characteristics of bolted flange connections. The proposed nonlinear analytical lump model has demonstrated significant accuracy and precision in capturing the nonlinear dynamic characteristics of bolted flange connections with spigots under various loading conditions. The proposed model clearly represents and characterizes the nonlinear phenomena of peak amplitude damping and frequency shift. It is also computationally efficient, making the model feasible for implementation when performing nonlinear analyses of large structural assemblies such as full aeroengine models. Moreover, the proposed analytical lump model is universal, permitting its implementation in various structures with different material properties and geometries. The validity and accuracy of the proposed model has been verified using nonlinear experimental test data for an aeroengine casing assembly.

Modeling and dynamic characteristic analysis of dual rotor-casing coupling system with rubbing fault

With the rapid development of aero-engine manufacturing technology, the dual-rotor system has been employed in part of turbofan engine in order to improve the working performance of aircraft more efficiently. In this study, taking the counter-rotation dual-rotor as the research object, the dynamic model of dual rotor-casing coupling system is established by the aid of MATLAB. The dynamic frequency curves are in good agreement with the results in references and calculated by FEM method, that shows the validity and feasibility of the model. The local rub-impact dynamic model of dual rotor-casing coupling system is established, and rubbing analysis is carried out using Newmark- β method. The effects of rotating speed and speed ratio on local rub-impact response are deeply discussed. The results show that with the increase of rotating speed, combined frequencies and frequency multiplication components are more significant. In addition, speed ratio has a great influence on the periodic motion of the system. With the increase of the absolute value of the speed ratio, the whirl radius of the outer rotor and the normal rubbing force increase dramatically.

A Probabilistic Approach for Three-Dimensional Variation Analysis in Aero-engine Rotors Assembly

Rotor assembly is a core tache in the whole process of aero-engine manufacturing. Preventing out-of-tolerance of concentricity is one of the primary tasks. Conventional assembly approaches are based on a manual test with the dial indicator, depending on experience appraises, which lack systematic and quantitative precision design theory. As a result, two issues need to be solved: the modeling problem of complicated geometric variations in three-dimensions, as well as the abnormal distribution of ubiquitous actual deviations. This work attempts to propose a novel probabilistic approach for three-dimensional variation analysis in rotor assembly. Based on rotor’s revolving characteristics and multistage stacking process, Jacobian–Torsor model is adopted to establish the variation propagation, and Pearson distribution family is used to derive the probability density function, which can quickly determine the variation distribution pattern and efficiently perform statistical variation analysis. A real case of mechanical assemblies consisting of revolving axisymmetric components is concerned. The results show that the suggested method has a similar accuracy, but much higher efficiency than conventional methods. Calculations agree with the experimentations, and the probability distribution type of the part’s variation has an appreciable impact on the final assembly precision.

Application and Development of Electronic Computers in Aero Engine Design and Manufacture

This paper has introduced the development of CAD and CAM at home and abroad, especially the application in aero engine; The development goal, implementation steps and assumption of computer system configuration of CAD / CAM technology for aero engine in China are put forward combined with the current situation of CAD / CAM technology in China.

Systematic design and implementation of a semantic assistance system for aero-engine design and manufacturing

Systematic design and implementation of a semantic assistance system for aero-engine design and manufacturing

Systematic design and implementation of a semantic assistance system for aero-engine design and manufacturing

Systematic design and implementation of a semantic assistance system for aero-engine design and manufacturing

Design and Implementation of Cloud Platform Knowledge Service Mode for High-end Equipment Manufacturing

With the advancement of intelligent high-end equipment manufacturing, knowledge in the field of high-end equipment manufacturing provides decision support and knowledge innovation services for all aspects of the product life cycle, and plays an increasingly important role in design and production. However, the multi-source, heterogeneous and fragmented nature of domain knowledge brings difficulties to the organization and management of knowledge. To solve this problem, this paper proposes a cloud platform knowledge service mode for high-end equipment manufacturing throughout the product life cycle, including three-dimensional knowledge classification standard, ontology-based knowledge representation and integration, knowledge sharing through knowledge navigation, knowledge retrieval and knowledge reasoning. The application of aerospace manufacturing related fields shows that this mode can provide effective knowledge support for the product life cycle, strengthen the production collaboration between upstream and downstream enterprises in high-end equipment manufacturing, and provide a comprehensive guarantee for the aeroengine manufacturing industry chain.

Impact of Exit Duct Dynamic Response on Compressor Stability

Abstract Abrupt distortions can appear as a result of transient crosswind or during rapid aircraft maneuvers. Such distortions are known to reduce the aerodynamic stability of engines and therefore present a major concern to all aero-engine manufacturers. To assess the aerodynamic stability of fan blades due to distortions, rig tests are usually carried out to establish the loss in stall margin. In such test campaigns, an exit duct (which is followed by a nozzle) is placed downstream of the fan blade, and the operating condition of the fan is controlled by this nozzle. It is shown in this paper that in such rig tests, the length of duct downstream of a fan has a significant impact on fan stall margin. The key contributor for such interaction is the dynamic response of the exit duct, and the aerodynamic stability of the fan is affected by the acoustic reflection from the exit nozzle. To study the underlying physics, transient response in the exit duct downstream of a transonic fan stage was studied numerically using a simplified model. Simulation results, along with calculations based on analytical theories, confirmed the generation, propagation, and reflection of waves induced by the inlet distortion. A quantitative relationship concerning the lengths of the compression system is introduced which determines whether a duct setup would have beneficial or detrimental influences on compressor aerodynamic stability. The findings of this research have great implications for the stability assessment of fans as the stability margin can be affected by the waves generated in bypass ducts.

CPS-Based Self-Adaptive Collaborative Control for Smart Production-Logistics Systems.

Discrete manufacturing systems are characterized by dynamics and uncertainty of operations and behavior due to exceptions in production-logistics synchronization. To deal with this problem, a self-adaptive collaborative control (SCC) mode is proposed for smart production-logistics systems to enhance the capability of intelligence, flexibility, and resilience. By leveraging cyber-physical systems (CPSs) and industrial Internet of Things (IIoT), real-time status data are collected and processed to perform decision making and optimization. Hybrid automata is used to model the dynamic behavior of physical manufacturing resources, such as machines and vehicles in shop floors. Three levels of collaborative control granularity, including nodal SCC, local SCC, and global SCC, are introduced to address different degrees of exceptions. Collaborative optimization problems are solved using analytical target cascading (ATC). A proof of concept simulation based on a Chinese aero-engine manufacturer validates the applicability and efficiency of the proposed method, showing reductions in waiting time, makespan, and energy consumption with reasonable computational time. This article potentially enables manufacturers to implement CPS and IIoT in manufacturing environments and build up smart, flexible, and resilient production-logistics systems.

A comprehensive review on blade tip timing-based health monitoring: status and future

As a promising way of on-line and non-intrusive blade vibration monitoring, the blade tip-timing (BTT) technique is currently being explored by almost all gas turbine or aero-engine manufacturers as replacing strain gauges. The principle of BTT seems to be simple, but how to make it effective in reality is indeed an interdisciplinary problem. In particular, aeroengines always operate under extremely complex environment, so that the BTT technique still faces many potential challenges. The main purpose of this paper is to review key developments, summarize possible issues and discuss the trends. After the brief introduction of BTT, three main challenges in BTT-based health monitoring are refined. Then developments of BTT probes, signal preprocessing and vibration monitoring are reviewed comprehensively. Finally, detailed prospects are discussed on future directions including but not limited to uncertainty calibration, deep compressed sensing, deep learning, fusion of BTT and blade tip clearance (BTC). In particular, an appeal is made that actual and raw BTT data can be shared in the academic and industrial communities in the future. This paper should provide a quick guide for future newcomers into this field.

Overall Framework Design of Integrated Manufacturing Center of Underground Laser Rapid Prototyping for Aeroengine Components Based on Cloud Computing and Internet of Things

This paper displaces an antiaircraft defence multi component integrated aeroengine manufacturing system which is designed for fast supply and timely repair of aeroengine in wartime. The robust control architecture is based on the global control of cloud computing and super expansion of the neural terminals of the Internet of things by fog computing. In order to improve the purpose of the whole system, we set up a system which can produce a variety of aeroengine components by the fog computing node with high autonomy. This relatively independent production system can receive intermittent commands from the cloud processor. For most of the time, each relatively independent laser rapid manufacturing unit runs the manufacturing task in the weak command environment. It only needs to send a decision from the cloud processor on the model and quantity of the aeroengine to be produced, and mark the changed parts with special requirements. Command encapsulation and encryption are carried out at the interface of the middle layer, and then sent down to the physical layer and the fog computing layer to realize macro command decryption and the production sequence of this batch of aeroengine production tasks configured to different number of laser manufacturing units.

A scientometric analysis and critical review of gas turbine aero-engines control: From Whittle engine to more-electric propulsion

The gas turbine aero-engine control systems over the past eight decades have been thoroughly investigated. This review purposes are to present a comprehensive reference for aero-engine control design and development based on a systematic scientometric analysis and to categorize different methods, algorithms, and approaches taken into account to improve the performance and operability of aircraft engines from the first days to present to enable this challenging technology to be adopted by aero-engine manufacturers. Initially, the benefits of the control systems are restated in terms of improved engine efficiency, reduced carbon dioxide emissions, and improved fuel economy. This is followed by a historical coverage of the proposed concepts dating back to 1936. A comprehensive scientometric analysis is then presented to introduce the main milestones in aero-engines control. Possible control strategies and concepts are classified into four distinct phases, including Single input- single output control algorithms, MIN-MAX or Cascade control algorithms, advanced control algorithms, More-electric and electronic control algorithms and critically reviewed. The advantages and disadvantages of milestones are discussed to cover all practical aspects of the review to enable the researchers to identify the current challenges in aircraft engine control systems.

5-axis milling of complex parts with barrel-shape cutter: cutting force model and experimental validation

The manufacturing of turbomachinery components for the aerospace sector is an important topic in machining research. Aeroengine manufacturing companies forecast increasing levels of design complexity and demand in the following years. Key elements are the Integral Bladed Rotor (IBR) parts, such as impellers and blade-disks. Despite advances in five-axis machining, manufacturing a reliable and efficient IBR component is still a challenge. In this work, the mechanics of the milling process with barrel-shape cutter is studied. These recently developed tools offer a potential advantage for a productive, chatter-free, high-performance machining of IBR parts. In this work, the cutting forces model is developed for this type of tools, then the model is verified in inclined milling operations.

A comprehensive study of three dimensional deviation analysis methods for aero-engine rotors assembly

Rotor assembly is a core tache in the whole process of aero-engine manufacturing. The assembly deviation analysis is an effective tool to control deviation propagation. For aero-engine rotors assembly, the traditional deviation control methods focus on the modeling of plane dimension chain and extremum analysis, which is difficult to comprehensively consider the rich geometrical errors and their relationship to each other; meanwhile, the precision prediction is too conservative to reduce the parts’ rework frequency and adjusting difficulty; In addition, traditional methods overemphasize the promotion of parts’ machining precision, and ignore the means of overall stack optimization. In recent years, three dimensional deviation analysis and control methods have a lot of developments. These methods synthetically consider the matters of size deviation, form and location deviation, fixing structure and the positioning relationship. The poor concentricity problem of gyro black assembly can be exactly described, which is beneficial to control assembly deviation. This paper deals with aero-engine rotors assembly problem from two perspectives: deviation expression and deviation propagation, gives the difficulties of this topic, and provides a detailed review on the most recent approaches about partial deviation expression and three dimensional chain propagation. Finally, a perspective overview of the future research about aero-engine rotors assembly is presented, such as rotors deformation, surface morphology representation and matching, and the relationship between assembly precision geometry and performance physical quantity.

On the vibration transfer path analysis of aero-engines using bond graph theory

Due to increases in fossil fuel prices worldwide, aero-engine manufacturers in the aerospace industry are introducing innovative designs that emphasize mass reduction, improving efficiency and lowering operating costs. However, this phenomenon has increased the exposure of aero-engines to vibration transfer, due to internal excitation loadings produced by issues such as rotor system unbalance. Due to these circumstances and the general advancement of aero-engine design technology, the demand for reductions in interior fuselage noise and vibration has increased. In this research, bond graph transfer path analysis (TPA) is extended to apply to aero-engines, with the goal of analyzing vibration propagation through the aero-engine's structural pathways. Bond graph TPA is a reliable and valuable method that can be utilized to efficiently diagnose and minimize noise and vibration problems during the design phase, prior to prototyping. One of the main advantages of bond graph TPA is its analytical algorithm, which attempts to circumvent the empirical limitations imposed by previously available TPA models such as operational path analysis and operational path analysis with exogenous inputs. The result is superior time efficiency when analyzing vibration propagation in structures such as aero-engines, especially as compared to earlier TPA methods which demand vast and extensive amount of experimental measurements which could be an inefficient approach at times In this study, the bond graph transfer path analysis methodology is explored and implemented on a reduced lumped model of an aero-engine in order to demonstrate this novel transmissibility analysis approach. Using this unique process, the concepts of global and direct transmissibility and path contribution in aero-engines were investigated based on the TPA methodology, and vibration reduction strategies proposed that will help to minimize vibration transfer to aircraft fuselages that originates from rotor's unbalanced forces.

Development of an automated non-axisymmetric endwall contour design system for the rotor of a 1-stage research turbine – part 1: System design

Secondary flows are a well-known source of loss in turbomachinery flows, contributing up to 30% of the total aerodynamic blade row loss. With the increase in pressure on aero-engine manufacturers to produce lighter, more powerful and increasingly more efficient engines, the mitigation of the losses associated with secondary flow has become significantly more important than in the past. This is because the production of secondary flow is closely related to the amount of loading and hence the work output of a blade row, which then allows part counts and overall engine weight to be reduced. Similarly, higher efficiency engines demand larger engine pressure ratios which in turn lead to reduced blade passage heights in which secondary flows then dominate. This article discusses the design and application of an automated turbine non-axisymmetric endwall contour optimization procedure for the rotor of a low speed, 1-stage research turbine, which was used as part of a research program to determine the most effective objective functions for reducing turbine secondary flows. In order to produce as effective as possible designs, the optimization procedure was coupled to a computational fluid dynamics routine with as high a degree of fidelity as possible and an efficient global optimization scheme based on the so-called efficient global optimization algorithm. In order to compliment the requirements of the efficient global optimization approach, as well as offset some of the computational requirements of the computational fluid dynamics, the DACE metamodel was used as an underlying surrogate model.

Q&A: Gareth Hedicker, Rolls-Royce

The Aero-Engine Manufacturer's Director of Development and Experimental Engineering–Civil Aerospace, Details the Physical Design Challenges of Testbed 80 and its Links to the Virtual World

Engine of innovation: the Royal Aircraft Establishment, state design and the coming of the gas turbine aero-engine in Britain

ABSTRACTBy the end of the Second World War, thanks to government encouragement and support, Britain’s aero-engine manufacturers had a series of world-beating axial jet engines. By tracing institutional changes, this paper will show how the Royal Aircraft Establishment’s remit expanded during the second world war to include state design of components of aero-engines for the first time. Overlooking the contributions of civil servants to innovation has made us blind to the many ways in which the British state supported and shaped new technologies.

On the design and feasibility of tantalum-base superalloys

In order to reduce the environmental impact of air travel, it is desirable that the efficiencies of gas turbine engines are increased. One way to achieve this goal is to increase the operating temperatures of the engine cores. Unfortunately for aero-engine manufacturers, the temperature capability limits of the Ni-base superalloys used currently have been reached. Hence, new alloys need to be developed that are capable of operating at significantly higher temperatures. In this article, the potential of tantalum-base superalloys is discussed and explored. A suite of alloys based on the Ta-Al-Co system was investigated. It was found that an array of fine carbide precipitates was formed in the Ta-rich matrix in a subset of the alloys, which is promising in terms of developing a strong and damage-tolerant microstructure, but that the elemental partitioning of Al out of the matrix accompanying precipitation is likely to degrade environmental resistance. Nevertheless, it is believed that the design principles described have the potential to facilitate the development of the next generation of high-temperature alloys based on systems of this type.

Core domain ontology for joining processes to consolidate welding standards

• Core domain ontology for joining processes (CDOJP), that can semantically categorise joining processes to reconcile the semantic inconsistency issues, is developed. • The proposed ontology is consolidated to the welding standards so that semantic inconsistencies can be effectively resolved. • This research is validated for semantic inconsistency resolving in an industrial environment via collaboration with one of the largest aero engine manufacturing companies. Extensive advancement in the field of the joining science has led to the development of a wide range of joining processes and techniques. Welding is one of the most widely used joining processes. Various standards have been developed to regularise welding processes and ensure manufacturing consistency. However, there are many inconsistencies and incoherencies in terms of process categorisation within and across the welding standards. It is imperative to undertake investigations on the limitations and issues of the current welding standards in semantic inconsistency, and then to reveal the inadequacy of text based definitions of welding concepts. To address the issues, in this paper, core domain ontology for joining processes (CDOJP), that can semantically categorise joining processes to reconcile semantic inconsistency, is developed. An ontological approach using Web Ontology Language (OWL) is used to define the ontology. The generic nature of the proposed ontology allows it to be applicable to various joining processes. The proposed ontology is further consolidated to the welding standards so that semantic inconsistencies in the standards can be effectively resolved. This research is validated in an industrial environment via collaboration with one of the largest aero engine manufacturing companies. The recommendations from this research are useful for the international standards committees to improve the joining and welding standards.