Engine Fan Research Articles

Impact of surface roughness on gas turbine engine fan and compressor rotor

Impact of surface roughness on gas turbine engine fan and compressor rotor

Mine auxiliary fan in the form of an intelligent mechatronic module

Introduction. High-quality ventilation of underground workings is an important condition for safe and accident-free mining. Research on aerological situation control in work areas is ongoing, but the problem of creating reliable adaptive ventilation systems for shafts and mines remains urgent despite the progress made. In course of excavation, the system of workings on the horizon develops a highly complex structure. Auxiliary ventilation is often the only way to achieve high-quality air exchange in the working area. Methods of research. To continuously provide the working area with an estimated amount of fresh air, as well as to intensify ventilation if the concentration of toxic contaminants is increased, mine auxiliary fans (MAF) are used. The best way to improve MAF environmental and economic efficiency is to automatically control the fan capacity. Results and analysis. The program embedded in the programmable logic controller (PLC) provides for comparing the transmitters readings and the aerological situation allowed by the parameters as well as making a decision on changing the fan capacity. If the change is required, the PLC sends an appropriate command to the controller to adjust the fan engine speed. The MAF scheme is simplified if the blind drift is straight because the transmitter is in the line of sight of the receiver and there is no need for a repeater. The UMP design is of a minimal complexity when the mine working is straight and the control task is limited to ensuring constant air flow supplied to the bottom-hole zone. Out of all the data devices, only the flow transmitter remains in the circuit, while the repeater and PLC are excluded. It should also be noted that during the entire period of tunneling, the fan of an unregulated MAF creates an excess power consumption, therefore consuming more electricity than the fan of an intelligent mechatronic module (IMM). Conclusions. Conversion of MAF to IMM will provide the required amount of fresh air to the bottom-hole zone increasing the safety of miners. Real-time control of IMM capacity will significantly reduce energy consumption and create favorable conditions for optimizing ventilation according to the “price-quality” criterion.

Application of MEMS Accelerometers in Dynamic Vibration Monitoring of a Vehicle.

In this paper, the viability of MEMS accelerometers is investigated to measure vibration parameters related to different locations of a vehicle with respect to the automotive dynamic functions. The data is collected to compare the accelerometer performances in different locations on the vehicle, including on the hood above the engine, on the hood above the radiator fan, over the exhaust pipe, and on the dashboard. The power spectral density (PSD), together with the time and frequency domain results, confirm the strength and frequencies of the sources of vehicle dynamics. The frequencies obtained from the vibrations of the hood above the engine and radiator fan are approximately 44.18 Hz and 38 Hz, respectively. In terms of the vibration amplitude, the measured amplitudes are between 0.5 g and 2.5 g in both cases. Furthermore, the time domain data collected on the dashboard during driving mode reflects the road condition. Overall, the knowledge obtained from the various tests conducted in this paper can be advantageous for further control and development of vehicle diagnostics, safety, and comfort.

A short review on SLM-processed Ti6Al4V composites

The advancements in computer-aided design, manufacturing, and additive manufacturing techniques attracted the researcher to apply various new methods with the unique combination of alloys and composites to design and develop complex parts. Among them the selective laser melting (SLM) process, a branch of additive manufacturing, and Ti6Al4V (Ti64) composite. Due to the better mechanical and corrosion resistance characteristics of Ti64 and its composites, they have been utilized for making various engineering parts related to jet engine fans of aero-engine, engine valves of automobiles, knee and hip joint endoprosthesis in the biomedical field, and corrosion resistance pipes in chemical industries. Also, more complex, net-shaped, and lattice-structured components can be fabricated by advancing the SLM process. The final quality of the parts manufactured from the SLM technique will depend on the fabrication process parameters followed. Many researchers have done research work on metal additive manufacturing by changing and optimizing the SLM process parameters such as laser power ( P), scanning speed ( v), hatch spacing ( d), and layer thickness ( h). Also, they have studied the effect of changes on the feedstock preparation, SLM process parameters, milling time of composite and post-heat treatment on the quality of Ti6Al4V composites. Therefore, a detailed review is needed to study the effect of the abovementioned parameters on the quality of metal additively manufactured parts through SLM. Hence, a short review is done on future challenges and opportunities of SLM-processed Ti6Al4V composites and reported in this article.

Evaluation of the Impedance Variability Effect of Acoustic Liner on Aircraft Engine Fan Noise in Calculation of Far Field Sound Modes Propagation

Evaluation of the Impedance Variability Effect of Acoustic Liner on Aircraft Engine Fan Noise in Calculation of Far Field Sound Modes Propagation

Improved RUL Predictions of Aero- Engines by Hyper-Parameter Optimization of LSTM Neural Network Models.

Abstract: In the industry domains such as transportation, power generation and heavy engineering industries utilize complex machinery, as their working principles are very complex and it is very difficult to predict their exact life and operational availability due to difficulties involved in their operations. PHM- Prognostics and health management is one such domain which supports in the management of this machinery also known as assets for continuous monitoring for their best utilization and maximum efficiency. For any machine, the current health of the system can be determined by operational and raw sensor data. This data can also be utilized for the prediction of remaining useful life (RUL) of the system provided a reliable prediction model is available. It is always be challenging to determine the remaining useful life of complex machines such as turbofan jet engines from the knowledge of the data available from operating conditions and sensor data. An HPT LSTM- advanced hyper parameter tuned LSTM- Long Short Term Memory neural network model is developed to accurately determine the remaining useful life of the turbojet fan engines. To test this predictive model, a NASA developed database CMAPSS- Commercial Modular Aero Propulsion System Simulation is used. The performance of this HPT LSTM is found to be much improved as compared to reference machine learning algorithms such as simple linear regression and Lagged Multi- Layer Perceptron Models

Realization of High Pressure Turbine Blades of a Small Turbo Fan Engine through Investment Casting Process

Turbo-fan gas turbine engines, or simply turbo-fan engines (STFEs), are used for powering both manned aircrafts and unmanned air vehicles (UAVs). The high pressure turbine section of such engines use Ni-base superalloy cast rotor blades because of their good mechanical properties at high operating temperatures. The present paper provides the technical/technological details of the various aspects associated with development and manufacturing of high pressure turbine blades (HPTBs) for utilization in an indigenously-developed small turbo-fan engine. Vacuum investment casting process has been adopted for realization of the above equiaxed components using a Ni-base superalloy

Research and Verification on the Solution of Pressure Fluctuation of the Fan Air Inlet of Civil Aircraft Pneumatic System

The cold side bleeds air of the precooler in the pneumatic system of civil aircraft is usually drawn out from the external bypass of the engine fan and enters the precooler for heat exchange through the fan air inlet, bellows, and fan air valve. When the fan air valve is closed, a closed dead cavity is formed in the fan air inlet. When the airflow passes through the mouth at high speed, the pressure of the fan air inlet into the mouth will oscillate at high frequency, resulting in pressure fluctuation, which will lead to the damage of the bellows and the loss of bleed air function. CFD is proposed in this paper. The method of dynamic simulation combined with limited test parameters successfully located the root causes of the fan air inlet pressure fluctuations, solved the fan air inlet pressure fluctuation phenomenon, and creatively put forward the fan air inlet with hat, fan air inlet with ventilation branch 2 broad categories, and 8 kinds of potential solution design train of thought. CFD simulation method is used to analyze and compare each potential solution in detail. Finally, the solution was selected according to the test results and applied to the aircraft.

Evaluation of the Impedance Variability Effect of Acoustic Liner on Aircraft Engine Fan Noise in Calculation of Far Field Sound Modes Propagation

The influence of the impedance variability of the acoustic liner of an air intake on aircraft engine fan noise in the far field has been studied. The calculations were carried out in an axisymmetric statement for single modes based on the finite element solution to the Blokhintsev equation for the acoustic potential. The acoustic liner impedance was determined from a well-developed semiempirical model that takes into account the influence of a high sound pressure level (SPL) and grazing flow. A procedure has been developed for calculating the propagation of single sound modes through the air intake of an aircraft engine with a variable liner impedance depending on the flow velocity and SPL at a local point. The calculation procedure has been validated. Calculations were made for single mode propagation into the forward hemisphere for an air intake on the wall of which the following conditions were set: rigid wall, constant impedance (the impedance does not change along the liner) and variable impedance (the impedance changes along the liner depending on the changes in the velocity of the grazing flow and SPL). According to the calculation results, it was found that constant and variable impedances yield different SPL values in the far field; as well, taking into account the impedance variability changes not only the SPL values in the far field, but also the direction of the maximum mode radiation.

Evaluation of flyover auralisations of today's and future long-range aircraft concepts

The European research project ARTEM (Aircraft noise Reduction Technologies and related Environmental iMpact) develops innovative aircraft noise reduction technologies such as advanced engine fan lining, metamaterials and low-noise high-lift systems applied to a vehicle with enhanced shielding of the engine noise, namely, a blended wing body. Using aircraft flyover auralisation in laboratory listening experiments, such future technologies can be evaluated with respect to human sound perception. To assess the reliability of such perception-based evaluations, the simulation chain should be validated with existing aircraft flyovers. This contribution presents a systematic and rigorous hierarchical validation of auralisations of current jet aircraft using field recordings. Uncertainty in the source modelling is considered by using two different prediction tools for partial sound sources. In addition to comparing computed noise indicators, a psychoacoustic validation is done in laboratory listening experiments with a 3D loudspeaker array. The validation comprises three levels: (i) direct comparison of auralisations with recordings to study the identifiability of auralisations, (ii) ranking of auralisations and recordings regarding plausibility, and (iii) subjective annoyance ratings to test whether auralisations and recordings differ with respect to noise effects. Further, first results on the comparison of a future concept with a current aircraft are presented.

Structural Analysis of Airplane Wing Using Composite and Natural Fiber Materials: A Survey

Abstract: Natural fiber-reinforced polymer-based composites are increasingly used in modern society due to their numerous benefits for uses in mechanical engineering. Polymer-based composite materials are widely employed in civil construction, automotive, aerospace, and many other industries due to their many benefits. Natural fibers can be used to create new, highperformance polymer materials because they are affordable, environmentally friendly, renewable, and partially and fully biodegradable. Examples of these fibers include EGR Glass R Glass, Carbon fiber, and S Glass, as well as kenaf, pineapple, sugarcane, hemp, oil palm, flax, and leaf. The purpose of this study is to explore the use of natural fibers and composites in the production of airplane wings, including mechanical characteristics, applications, and potential as well as problems and future demand for natural composite materials for engineering uses. A good 50% of the airspace's components are natural composites. Because natural composites have the ability to lower aircraft weight, they are currently being used to construct helicopters, military fighter aircraft, small and large civil transport aircraft, cockpits, satellites, launch vehicles, and missiles. Rudder, spoilers, LG doors, keel beam, airbrakes, elevators, turbine engine fan blades, propellers, rear bulkhead, wing ribs, main wings, interior fixtures, etc. Composites made of natural fibers are attractive and promising. The use of natural fiber-based composite materials is growing daily due to their strength and integrity. The natural fiber is a renewable, environmentally beneficial, and biodegradable raw material. Both its mechanical and thermal insulation qualities are strong in natural fiber. However, the loading placed on the natural fiber and its youthful modulus determines its strength In addition to discussing the benefits of natural fibers over other materials, this paper provides a description of the several types of natural fiber, their physical and mechanical properties, and their advantages.

Development of Engine Maintenance Technology with Mixed Reality-Taking Pratt & Whitney JT9D as an Example

The engine is the heart of the aircraft and deeply affects performance, flight safety, and airline management, which makes it a critical component requiring maintenance. With the advancement of technology, augmented reality (AR), virtual reality (VR), and mixed reality (MR) technologies have been introduced one after another. To increase maintenance skill ability, it is important to train for aviation maintenance. Therefore, the engine maintenance mixed reality (EMMR) system was developed through mixed reality technology in this study. There are three different scenarios have been developed in the EMMR system for making engine maintenance easy. In the first scenario, an exploded diagram of the disassembled engine with the main components has been made and an animation of the fuel flow has been demonstrated to introduce the basic structure of the engine. In the second scenario, interactive buttons and animations have been used to simulate the removal of the engine from the wing of an airplane so that the users can understand the process of disassembling the engine. In the third scenario, hybrid reality has been implemented to interact with the virtual objects, so that users could simulate the disassembly and replacement of the engine fan blades and get familiar with the whole process. Students have been introduced to and have been familiarized with the Microsoft HoloLens 2 and a survey has been conducted before and after using the developed technology to understand if the currently developed EMMR could help students to understand the process of each engine maintenance in the general classroom and make the learning more efficient at the same time.

Machine learning augmented multi-sensor data fusion to detect aero engine fan rotor blade flutter

Abstract Flutter-induced fatigue failure investigation of the fan blades of aero-engines necessitates extensive testing. During engine ground testing, strain gauges on rotor fan blades and casing vibration sensors were employed to investigate structural dynamic aspects. The correlation between strain sensor signals and fan casing vibration signals allowed the diagnosis of fluttering fan blades. For automated flutter detection during engine development testing, a machine learning-augmented information fusion methodology was developed. The method analyses casing vibration signals by extracting time-domain statistical features, intrinsic mode function characteristics through empirical mode decomposition, and recurrence quantification features. Feature vectors obtained from a relatively large set of engine tests were subjected to dimension reduction by applying machine learning techniques to rank them. Reduced feature vector space was labelled as “flutter” or “normal” based on the correlation of rotor strain gauge signals. In addition, the labelled feature vectors were employed to train classifier models using supervised learning-based algorithms such as Support Vector Machines, Linear Discriminant Analysis, K-means Clustering, and Artificial Neural Networks. Using only vibration signals from the casing, the trained and validated classifiers were able to detect flutter in fan baldes with a 99% probability during subsequent testing.

Nacelle intake flow separation reduction at cruise condition using active flow control

Turbofan engine intakes are designed to provide separation-free flow at the fan face over a wide range of operating conditions. But at some off-design conditions, like at high flight speeds and high angles of attack (AoA), the aero engine intake may encounter flow separation. This boundary layer separation inside the nacelle inlet of an aircraft engine can lead to a large number of undesirable outcomes like reduction in fan efficiency, engine stall and high levels of stress on the fan blades. Active flow control is a promising solution to reduce inlet boundary layer separation and the associated fan-face flow distortion at such off-design conditions. By blowing pressurized air into the intake near the separation point, the boundary layer is energized and separation can be controlled. This study investigates the applicability of lip blowing, an active flow control technique, to control intake separation and flow distortion at the fan-face. First, intake separation was triggered in a 3D CFD model based on the NASA Common Research Model (CRM) using high AoA cases at cruise condition (Mach number 0.85, Mass flow capture ratio ∼0.7) and the features of separated flow were analyzed. Thereafter, active flow control was introduce to the intake in the form of two types of lip blowing, direct and pitched blowing. The efficacy of lip blowing at achieving separation control in an ultra high bypass ratio turbofan engine intake has been established through this study. The present paper also examines the significance of blowing parameters like the type of blowing, blowing pressure ratio, and blowing slot dimension, at different angles of attack to identify the critical control parameters. Our research successfully establishes proof of concept by demonstrating the feasibility of using lip blowing for separation control in aero-intakes, via numerical modelling. Furthermore, this study also provides crucial insights regarding the important variables to be considered for future experimental studies, and also for detailed studies covering a wider range of operating and blowing conditions.

Determination of the Geometric Properties of a Jet Engine Fan Blades Based on Modal Vibration Testing

Abstract The article presents an experimental method of determining the geometric properties of jet engine rotor airfoils based on modal vibration testing. The procedure is based on adjusting the results of analytical calculations to the laboratory outcomes. Experimental tests were carried out on a set of 20 jet engine fan blades made of AL7022-t6 aluminium alloy. Each blade differed in weight and geometric dimensions within the accepted design tolerance. Numerical analysis of five airfoils that differed in thickness was performed. Modal vibration test results were summarised and compared with the results obtained by the numerical method. The comparison revealed a high similarity of the frequency and form of vibrations acquired by numerical simulation for each of the blades in relation to the executed vibration testing. Based on the verification of the theoretical model with the results obtained through experimental testing, conclusions were drawn about the object’s dynamic behaviour and its technological quality and geometric properties, whereby each of airfoil was probably thinned.

Semi-Physical Simulation of Fan Rotor Assembly Process Optimization for Unbalance Based on Reinforcement Learning

An aero engine fan rotor is composed of a multi-stage disk and multi-stage blades. Excessive unbalance of the aero engine fan rotor after assembly is the main cause of aero engine vibration. In the rotor assembly process, blade sequencing optimization and multi-stage blade set assembly phase optimization are important for reducing the overall rotor unbalance. To address this problem, this paper proposes a semi-physical simulation method based on reinforcement learning to optimize the balance in the fan rotor assembly process. Firstly, based on the mass moments of individual blades, the diagonal mass moment difference is introduced as a constraint to build a single-stage blade sorting optimization model, and reinforcement learning is used to find the optimal sorting path so that the balance of the single-stage blade after sorting is optimal. Then, on the basis of the initial unbalance of the disk and the unbalance of the single-stage blade set, a multi-stage blade assembly phase optimization model is established, and reinforcement learning is used to find the optimal assembly phase so that the overall balance of the rotor is optimal. Finally, based on the collection of data during the assembly of the rotor, the least-squares method is used to fit and calculate the real-time assembly unbalance to achieve a semi-physical simulation of the optimization of balance during the assembly process. The feasibility and effectiveness of the proposed method are verified by experiments.

Numerical Investigation of the Influence of Air Contaminants on the Interfacial Heat Transfer in Transonic Flow in a Compressor Rotor

Atmospheric air is a commonly used working fluid in turbomachinery. The air typically contains a certain amount of suspended solid particles, as well as water in the form of vapor or droplets. In the current paper, we focus on the numerical modeling of humid air transonic flow in turbomachinery. In this paper we demonstrate a rarely considered, but as presented herein important influence of air humidity, pollution and liquid water content on the performance of the first stage of the gas turbine compressor and turbofan engine fan (NASA rotors 37 and 67). We also discuss the impact of the interfacial heat transfer associated with steam condensation or water evaporation on the distribution of stagnation parameters at the rotor outlet, the rotor performance, and flow conditions, as well as losses. Results demonstrate the impact of the number of pollution particles and water droplets on the compression process in the analyzed rotors, especially on the Mach number distribution in the blade-to-blade channel. In this paper we highlight that the air pollution and liquid water content, together with such physical phenomena as steam condensation or water droplets evaporation, exert a significant influence on work parameters, losses and efficiency, and thus should be considered in high-velocity airflow simulations.

Sensitivities of Aircraft Acoustic Metrics to Engine Design Variables for Multidisciplinary Optimization

Aircraft environmental performance metrics including fuel burn, takeoff and landing noise, and gaseous emissions are increasingly driving the design and optimization of modern aircraft engines. Gradient-based methods can significantly reduce the computational resources required during their multidisciplinary optimizations. However, current state-of-the art noise modeling tools do not allow for effective computation of sensitivities of acoustic metrics with respect to engine design and control variables, and therefore cannot be easily integrated into multidisciplinary optimization tools. This paper presents the utility of the python Noise Assessment tool (known as pyNA): an aircraft noise estimation model providing sensitivities of acoustic metrics, enabling multidisciplinary optimization and optimal control of engines for low-noise aircraft. The model is used to assess the trades of environmental performance metrics in the clean-sheet engine design for the NASA supersonic technology concept airplane. For the engine examined, if the fan diameter is allowed to change while technology levels are held constant, the takeoff noise levels and emissions are found to be most sensitive to the design fan pressure ratio. For an engine with a fixed fan diameter, takeoff noise levels are found to be insensitive to design variables; whereas nitrogen oxide emissions and cruise thrust-specific fuel consumption are most sensitive to the engine fan and high-pressure compressor pressure ratios.

Predicting remaining useful life of turbofan engines using degradation signal based echo state network

Abstract The field of Prognostics and Health Management (PHM) in industries is gaining greater popularity to achieve high reliability by shifting the preventive maintenance to predictive maintenance. Estimation of Remaining Useful Life (RUL) is an effective prognostic measure that forecasts the health state of machine based on degradation modelling and condition monitoring. This article proposes a novel and robust methodology that uses Reduced Affinity Propagation (RAP) clustering technique that extracts representatives from the temporal signals measured through various heterogeneous sensors to predict the RUL using Echo State Network (ESN) with dynamic lateral inhibiting connections. The main advantage of the proposed model is that it does not overlook the features from the degradation signals and also learns the natural mapping among the representative points from the integrated sensor value. This approach is verified using CMAPPS dataset to show hopeful results in predicting the RUL of aircraft turbo fan engine. Also, this methodology can be a deployed as a tool in real time industrial applications to schedule predictive maintenance activities.

Exploration of an unconventional validation tool to investigate aero engine transonic fan flutter signature

Abstract Flutter, an aeroelastic blade vibration phenomena, experienced by the fan of an developmental aero gas turbine engine, result in blade failure. Hence, suitable flutter detection instrumentation is required during engine testing. Flutter signature capture from revolving blades is a challenging task that necessitates either a complicated strain gauge-based rotating instrumentation or a noncontact tip timing system. Authors investigated a unique way for identifying, measuring, and validating flutter signature by assessing wall static pressure pulsations produced during blade tip transit across a casing mounted high bandwidth sensor during this research. The authors devised a mathematical model to explain signal spectrum components that feature both amplitude and angle modulation properties at the same time. The theory was tested using first-stage fan rotor blades that were fluttering in the first flexural mode (1F) and forming the second nodal diameter (2ND). The approach’s estimated blade deflection was compared to measurements taken using a traditional tip timing method up to 7 mm and determined to be within 1% inaccuracy. This research provides a low-cost, easy alternative technique for measuring flutter during engine development testing.