Real Engine Operation Research Articles

Assessment of the effectiveness of mounting the aircraft piston combustion engine on a test stand

The subject of the considerations described in the paper is the problem of efficiency of mounting an aircraft engine on a dyno test bench. The paper presents the empirical research results of vibroacoustic signal application to the evaluation of correctness of positioning of the Rotax 912 piston aircraft engine. The variability of selected parameters and vibroacoustic characteristics for real engine operating conditions was assessed, and functional relations and their discrete representations were developed, reflecting the efficiency of mounting the object on the frame. Thanks to this process, quantitative measures of the diagnostic assessment of the object were obtained, which can be used in periodic or continuous operational control of the object, taking into account the impact of tribological processes taking place in the test object.

Revisitando e comparando o Ciclo de Carnot e o Ciclo Otto

The reversibility of the Carnot Cycle makes it the most efficient thermodynamic cycle to convert energy as heat into work operating between two thermal reservoirs at different temperatures. The Otto cycle represents an idealization of the processes in the spark-ignition 4-stroke internal combustion engine operation. Some aspects of these two crucial thermodynamic cycles will be presented here in a comparative manner. This highlights why the Carnot Cycle does not offer advantages over the Otto Cycle in the operation of real thermal engines when we consider the efficiency and work done per cycle dependent on the compression ratio of the cycles.

Increasing energy efficiency as a result of the influence on the operation of a Sano automobile engine with the adding of hydrogen as an additive to primary fuel

This article discusses a method for reducing emissions of toxic and harmful substances into the environment through the use of a composite fuel mixture in vehicles with an internal combustion engine. When using composite fuel, that is, using hydrogen as an energy carrier, during operation, by increasing the energy efficiency of the car engine and improving its environmental performance, the following indicators are achieved: high speed and completeness of combustion of the fuel mixture; the ability to bring the mixture in real internal combustion engine operation closer to ideal by providing heat in a constant volume; and an analysis of the dependence of engine efficiency on the addition of hydrogen to the main fuel is presented.

The Investigation of the Mixture Formation and Combustion Characteristic of the Spray-wall Impingement

In recent years, investigations into the formation of mixture or combustion characteristics of diesel spray-wall impingement have been summarized. On one hand, the air entrainment strength and fuel concentration distribution in the near-wall area during the spray-wall collision process have been studied. On the other hand, the combustion characteristics of the impinged spray, including ignition and combustion characteristics, have also been discussed. Additionally, the effect of impingement between spray and wall on real diesel engines’ operating condition has been analyzed and summarized. Results showed that increasing the pressure of the injection and shortening the collision distance could enhance the air entrainment strength of spray-wall impingement. Moreover, increasing the injection pressure, shortening the impingement distance, decreasing the environmental pressure, increasing the wall temperature, and reducing the nozzle diameter all improved the mixture formation. Conversely, reducing the environmental temperature, decreasing the nozzle diameter, and increasing the impingement distance all reduced the concentration of soot, and even achieved no soot formation. Under real diesel engine operation conditions, some of the soot formed in the spray-wall collision and deposited on the wall. The structure of these deposits was mainly a simple cluster structure composed of several basic particles, and the porous structure of the deposits was conducive to the oxidation of soot and reduced the deposition rate.

The Working Cycle of the Motoring Internal Combustion Engine by a New Method with Cylinder Pressures as in Real Engine Operation

Abstract The current standard methods of determining the mechanical losses of the ICE by motoring do not correspond to the low pressures in the cylinders of real engine operation. The new tried and tested method of determining passive resistances by motoring ICE with high working pressures in the cylinders is based on blowing doses of compressed air into the cylinders around BDC with special self-acting valves. When motoring with the new method, the same course of pressures in the cylinders and the same load on the crank mechanism, including the piston group, is achieved during combustion. The measurement proved the problem-free functionality of the self-acting valves, and the conducted experiments provided data on the dependence of mechanical and heat losses in the ICE on the working pressures in the cylinder.

Numerical modeling of diesel and polyoxymethylene dimethyl ether spray in a high pressure chamber using the fischer primary breakup model

In the strive for the climate-neutral and ultra-low emission vehicle powertrains of the future, synthetic fuels produced from renewable sources will play a major role. Polyoxymethylene dimethyl ethers (POMDME or “OME”) produced from renewable hydrogen are a very promising candidate for zero-impact emissions in future CI engines. To optimize the utilisation of these fuels in terms of efficiency, performance and emissions, it is not only necessary to adapt the combustion parameters, but especially to optimize the injection and mixture formation process. In the present work, the spray break-up behavior and mixture formation of OME fuel is investigated numerically in 3D CFD and validated against experimental data from optical measurements in a high pressure/high temperature chamber using Schlieren and Mie scattering. For comparison, the same operating points using conventional diesel fuel were measured in the optical chamber, and the CFD modeling was optimized based on these data. To model the spray-breakup phenomena reliably, the primary break-up model according to Fischer is used, taking into account the nozzle internal flow in a detailed calculation of the disperse droplet phase. As OME has not yet been investigated very intensively with respect to its chemico-physical properties, chemical analyses of the substance properties were carried out to capture the most important parameters correctly in the simulation. With this approach, the results of the optical spray measurement could be reproduced well by the numerical model for the cases studied here, laying the basis for further numerical studies of OME sprays, including real engine operation.

Forced Response System Identification of Full Aero-Engine Rotordynamic Systems for Prognostics and Diagnostics

Abstract A first-of-its-kind forced-response system identification approach is introduced to measure rotordynamic damping of shaft modes in a full gas turbine aero-engine. The approach involves forced-response modal analysis in which the rotordynamic system is excited with an external shaker, and engine modal characteristics are extracted from rotor shaft response signals. A reduced-order modeling framework capturing full-engine dynamics and coupling between rotor shafts and support static structure was developed and implemented in a Pratt & Whitney Canada PW615 Turbofan engine. The framework was used to guide the design of forced-response system identification experiments. The design study shows that two orthogonal shakers are required to excite both forward- and backward-whirling shaft modes and that excessive forcing amplitudes that produce whirl over 0.4 of journal eccentricity ratio can yield up to 12% lower response magnitudes due to nonlinear bearing characteristics. A statistical analysis of virtual experiments under real engine operating conditions demonstrates feasibility and robustness of the approach, measuring rotordynamic damping for key shaft modes with an uncertainty of up to 15%. General applicability of the approach with similar error levels is suggested for multispool multiframe aero-engine architectures. Guidelines for experimental setup, data acquisition, and processing are established for full-engine forced-response system identification experiments. The new capability shows promise in supporting aero-engine diagnostics and prognostics to improve the life cycle operation of commercial and military engines.

Experimental Investigation into the Effects of Fuel Dilution on the Change in Chemical Properties of Lubricating Oil Used in Fuel Injection Pump of Pielstick PA4 V185 Marine Diesel Engine

The engine oil contamination caused by various chemical elements and fuel is an important problem. As a consequence, the engine oil loses its tribological properties, engine lubrication worsens and may lead to potential problems such as excessive wear, corrosion, etc. For that reason, the study of oil degradation and contamination due to the replacement strategies is of special interest to the engine operators and engine manufacturers. In this paper, the chemical elements and fuel dilution of engine oil are analyzed under real engine operating conditions. This research is focused on the fundamental question: how is the chemical performance of lubricant components impacted by diesel dilution? Various tribological tests were performed on regularly collected samples from the fuel injection pump of a Pielstick PA4 V185 marine diesel engine. These tests assessed the influence of fuel on the lubricating oil chemistry performance and useful residual life. Tests included variations in lubricant density, viscosity, flash point temperature and chemical components for 10 samples taken in the following hours of engine operation. Results suggest that diesel dilution only slightly affects chemical additive performance. Most of the examined chemical elements remained at a negligible level (below 1 ppm) in the case of elements whose content was greater, and the changes were either negligible (Al, Fe, MG, Si) in the grits from 1 to 5 ppm or higher (Ca, P, Zn, C), ranging from tens to several hundred ppm. On the other hand, the kinematic viscosity changed significantly from 89.8 to 12.0 cSt at 40 °C or from 9.8 to 2.9 cSt at 100 °C. The change in flash point, although significant from 236 (for fresh oil) to a value below 100, does not exceed the limit values. To sum up, the study concluded that the reduction in oil change intervals for this engine is worth considering under the given operating conditions.

New Ways to Measure Mechanical Losses by Motoring an ICE with Increased Cylinder Pressure

The article shows the results of measuring the mechanical losses of a piston engine in two new ways and explains the necessary engine modification for these measurements. At the same time, it compares the results of measuring mechanical losses in the internal combustion engine (ICE) in the current (hitherto exploited) way and in new ways. The first method is not replacing the cylinder charge and regulating the cylinder pressure by feeding compressed air through self-acting valves into the cylinders of the motoring engine. The second method is a closed working cycle by means of an exhaust–intake connection, in which the load pressure in the cylinder is adjusted and maintained by a controlled-intake air supply. With the current method of measuring mechanical losses of a reciprocating internal combustion engine (ICE) by motoring, there are less than half the pressures in the cylinder compared to the pressures during real engine operation (i.e., in the combustion mode). Lower pressures in the cylinder reduce the force load on the piston group and the crank mechanism, and the detected mechanical losses in the engine are thus significantly reduced compared to the reality. In the laboratories of the propulsion units of the Faculty of Mechanical Engineering of the Technical University in Liberec, research is underway on a new method of measuring mechanical losses of a reciprocating internal combustion engine by motoring with charge pressure profiles in engine cylinders comparable to cylinder pressures during standard engine operation. The paper shows the results of measuring the mechanical losses of a piston engine in two new ways and explains the necessary adjustment of the engine for these measurements. At the same time, it compares the results of measuring mechanical losses in a reciprocating engine in the current (hitherto used) way and new ways. The first method is not changing the cylinder charge and regulating the pressure in the cylinder by inserting compressed air through automatic valves into the cylinders of the motoring engine. The second method is a closed working circuit involving connecting the exhaust to the intake, in which the charge pressure in the cylinder is set and maintained by a controlled supply of compressed air to the intake manifold. The first method proved to be a more suitable way to investigate mechanical losses in ICE and determine the dependence of these losses on the pressure conditions in the engine cylinder.

Numerical investigation of the breakup mode and trajectory of liquid jet in a gaseous crossflow at elevated conditions

ABSTRACTThe commercial Computational Fluid Dynamics (CFD) software STAR-CCM+ was used to simulate the flow and breakup characteristics of a Liquid Jet Injected into the gaseous Crossflow (LJIC) under real engine operating conditions. The reasonable calculation domain geometry and flow boundary conditions were obtained based on a civil aviation engine performance model similar to the Leap-1B engine which was developed using the GasTurb software and the preliminary design results of its low-emission combustor. The Volume of Fluid (VOF) model was applied to simulate the breakup feature of the near field of LJIC. The numerical method was validated and calibrated through comparison with the public test data at atmospheric conditions. The results showed that the numerical method can capture most of the jet breakup structure and predict the jet trajectory with an error not exceeding ±5%. The verified numerical method was applied to simulate the breakup of LJIC at the real engine operating condition. The breakup mode of LJIC was shown to be surface shear breakup at elevated condition. The trajectory of the liquid jet showed good agreement with Ragucci’s empirical correlation.

Promoted three-way catalytic activity of the Co3O4/TiO2 catalyst by doping of CeO2 under real engine operating conditions

With the aim to meet ever-increasing strict regulations for three major exhaust gas pollutants, three-way catalytic technology has been effectively applied in automobile industries for purifying automobile exhaust gases. Here we report the efficiency of composite oxide Co3O4/TiO2 with the addition of CeO2 as a promotor. Modification of Co3O4/TiO2 (15 wt%. Co/TiO2) based composite catalyst synthesized by incipient wetness impregnation (IWI) method was followed by doping of ceria (CeO2). The series of catalysts assigned as 15% IWI, 03-CE-IWI, 06-CE-IWI, and 09-CE-IWI having cerium content from 0 to 9 wt%, respectively were prepared. The same relative Co3O4/TiO2 ratio i.e., 15 wt% was sustained in the CeO2-doped catalysts for clarifying the impact of CeO2 and its doping quantity for CO and HC oxidation along with NOx reduction. The catalysts were characterized by Scanning Electron microscopy (SEM), X-ray Diffraction (XRD), and Brunauer–Emmett–Teller (BET). The catalysts three-way catalytic converter efficiency was assessed, mounted on a motorcycle engine with an engine capacity of 70 cm3 spark ignition. It was evaluated under steady-state operational conditions. The results revealed the strong impact of doping of CeO2 on Co3O4/TiO2 composite under real engine operating conditions and the maximum doping, i.e., 09-CE-IWI can considerably enhance the surface area (41.5 m2/g). The improved performance can be credited to a higher dispersion of Co3O4/TiO2 due to CeO2 doping, possessing a higher surface area as compared to ceria undoped catalysts, and there exists a catalytic synergistic effect of Co3O4 and CeO2. The 09-CE-IWI revealed the best catalytic activity for all three constituents i.e., CO and unburned HC at 6000 rpm and NOx specifically at 2000 rpm. Maximum three-way catalytic conversion efficiencies achieved in the case of CO, HC, and NOx are 92%, 83%, and 90%, respectively.

Film Cooling Patterns over an Aircraft Engine Turbine Endwall with Slot Leakage and Discrete Hole Injection

Detailed characteristics of film cooling from discrete injection and purge flow, and associated coolant injection patterns are presented over a turbine endwall for wide engine-representative coolant flow rate ranges. Measurements, in combination with numerical simulations, are performed in a linear cascade that is geometrically and aerodynamically scaled up from the hub section of the turbine vane. Reynolds numbers at the vane cascade inlet are varied from 1.40 × 105 to 4.20 × 105, representing the variations of real engine operating conditions (from take-off to cruise conditions). In order to examine the isolated and combined cooling effects, discrete coolant injection and purge flow for the endwall cooling can be injected separately or simultaneously. Numerical simulations are conducted to gain further insight into interactions between endwall-nearby secondary flows and coolant injection. Additionally, a net heat flux reduction parameter is used to evaluate overall film cooling performance of the cooling scheme, that takes heat transfer enhancement by coolant injection into consideration. Results show that endwall-nearby flow structures dictate thermal protection patterns. Increasing coolant flow rates decreases effectiveness values of discrete film cooling but improves cooling effectiveness of purge flow. In spite of no direct interactions between discrete injection and purge flow, adding purge flow could help enhance discrete film cooling effectiveness. Higher passage inlet Reynolds number leads to reduced mixing of coolant injection and mainstream flows, resulting in improved effectiveness values. Changing trends of overall cooling performance for purge flow and discrete film cooling by increasing coolant flow rates are opposite but those are the same by increasing Reynold numbers.

Exhaust energy recovery via catalytic ammonia decomposition to hydrogen for low carbon clean vehicles

The work presented here, demonstrates the on-board exhaust assisted catalytic ammonia (NH3) conversion to H2-N2 using either only exhaust heat (decomposition) or by direct reaction with part of the exhaust gas (reforming). The resultant H2-N2 gas mixture from the exhaust heat driven thermochemical energy recovery processes contains up to 15% more energy than the reactant NH3 (i.e. for 1 kW of NH3 used in the reaction up to 1.15 kW of H2 is produced). Experimental studies using a rhodium-platinum (Rh-Pt) catalyst and equilibrium calculations in Chemkin using Konnov’s 0.6 and Nozari’s reduced mechanisms have revealed that complete NH3 conversion occurs at typical gasoline direct injection (GDI) engine exhaust gas temperatures (450 °C–550 °C).By partially replacing gasoline in GDI engine with the resultant (H2-N2 products, up to 30% reduction in CO2 and fuels consumption can be achieved. Additional benefits can be gained under real engine operation when the benefits of reduced pumping losses, due to intake dilution with H2-N2 gas, are also considered. Furthermore, the work demonstrates additional benefits in CO2 life cycle for the NH3 use as an energy carrier in transportation and broader combustion power generation systems.

Influence of morphology and microstructure on the tribological behavior of arc deposited CrN coatings for the automotive industry

PVD coatings are widely used in the automotive industry for tribological purposes. In heavy-duty diesel engines, piston rings represent a challenging component concerning its tribological performance. Top piston rings were designed as an additional part with a supporting role in the sealing or prevention of gas leakages from the combustion chamber. Several sudies have been published proposing metal nitride coatings for the piston ring's functional surface. CrN coatings are among those most frequently proposed, but regularly using magnetron sputtering as the predefined deposition method. In a large-scale production framework, different deposition methods with improved deposition rates must be adopted. Cathodic arc deposition is currently widely implemented in several industries, such as in the automotive one. Although this technique is consolidated in the industrial environment, the deposition process and parameters are continuously under optimization.In the present study,two different CrN coatings deposited on the piston ring's functional surface are studied. Using other deposition conditions, two distinct morphologies are achieved in the coating layer: a denser structure (CrN-A) and a columnar structure (CrN-B). Those coatings were tested using a locally developed test rig, adapted to test the piston rings under conditions close to the real engine operation. The microstructure and mechanical properties of the CrN-A and CrN-B coatings were evaluated using X-ray diffraction and micro-indentation. The surface morphology and wear mechanism were characterized using SEM and EDS techniques before and after to perform the wear and friction tests.

Effects of low-pressure EGR on gaseous emissions and particle size distribution from a dual-mode dual-fuel (DMDF) concept in a medium-duty engine

The application of a low-temperature combustion concept, such as RCCI combustion under real engine operating conditions is extremely complex. However, the implementation of the dual-mode dual-fuel (DMDF) strategy allows operating in low-medium load with the RCCI combustion and in high load with dual-fuel diffusive combustion. This allows taking advantage of the benefits of RCCI combustion as the simultaneous reduction of PM and NOx emissions. However, there are still serious challenges that required to solve, such as the high-pressure rise rate and the excessive CO and HC emissions. In this sense, this work shows how the implementation and an adequate adjustment of the cooled LP-EGR rate significantly minimize these problems and also shows how the LP-EGR has a greater impact on the DMDF than on the CDC concept.This work has been performed in a modern medium-duty diesel engine fueled with standard gasoline and diesel fuels, with which a cooled LP-EGR loop has been coupled. A TSI Scanning Particle Sizer (SMPS 3936L75) was used to measure the particles size distribution and the Horiba MEXA-ONE-D1-EGR gas analyzer system to determine gaseous emissions. A parametric variation of the LP-EGR rate was experimentally performed to analyze the effect over each combustion process that encompasses the DMDF concept (fully premixed RCCI, highly premixed RCCI and dual-fuel diffusion) and its consequent impact on gaseous and particle emissions. In addition, results were compared against the CDC concept to state the benefits of the DMDF concept. Among the different results obtained, it can be highlighted that during the RCCI strategy the increase in LP-EGR rate provided a reduction in NOx emissions. Nonetheless, unlike that fully premixed RCCI in highly premixed RCCI combustion, the PM emissions increased with this increment in the LP-EGR rate, shifting the size distribution of particle toward larger sizes, but decreasing the HC and CO emissions. Finally, with the exception of the high HC and CO emissions in fully premixed RCCI, in all the combustion strategies of the DMDF concept, a reduction of the analyzed pollutants was observed when compared with the CDC mode.

Numerical Prediction of Mixture Formation Process of an Ethanol Spray in a Rapid Compression and Expansion Machine

This study deals with the development of controlled-ignition technology for high performance compression ignition alcohol engines. Among the alcohol fuels, we focused on Ethanol as a promising candidate of alternative fuels replacing from petroleum. In our previous study, visualization tests of spray mixture formation process up to auto-ignition for Ethanol-Diethyl either blend fuels had been conducted by using a constant volume electrical heating combustion chamber. Quantitative evaluation of auto-ignition quality was summarized in a form of 3D map that indicates the effects of surrounding gas pressure, temperature and Oxygen concentration on ignition delay. However, maximum surrounding gas pressure in the experiments was 2.8MPa much less than that of real engine due to the structure of the combustion chamber. As the next step, we originally designed and manufactured a RCEM (Rapid Compression and Expansion Machine with variable compression ratio) in order to investigate the mixture formation process up to auto-ignition of an Ethanol spray under surrounding gas conditions similar to real engine operating conditions with the consideration of the interaction between fluid motion of surrounding gas and fuel injection. Prior to carrying out the experiments, we numerically predicted the auto-ignition quality of an Ethanol spray in the rapid compression and expansion machine. One of the commercial CFD codes; CONVERGE was used in the computational calculation with the considerations of turbulence, atomization, evaporation and detailed chemical reaction. Effect of fluid motion and surrounding gas pressure and temperature inside the combustion chamber of the RCEM on an Ethanol spray mixture formation is mainly discussed in this paper.

Efficiency enhancement of spark-ignition engines using a Continuous Variable Valve Timing system for load control

In this work, a Continuous Variable Valve Timing (CVVT) system for load control in spark-ignition engines is proposed, analyzed, and compared with a conventional Throttle-controlled Engine. An analytical model for ideal processes is initially developed to study the performance of both cycles during part-load operation. Then, irreversibilites comprising charging dilution effects and heat losses during compression and expansion strokes are considered to approach a more realistic engine operation. At full-load, both cycles reach a maximum efficiency corresponding to that of an Otto cycle. However, a reduction in the efficiency occurs at part-load operation, with the CVVT Engine having a higher efficiency with respect to the Throttled Engine due to its unthrottled load control mechanism, which avoids power consumption caused by friction during air intake. It is found that charge dilution exerts a strong impact in the net power output and efficiency of both cycles. Additional reductions in power output and efficiency are caused by heat losses. At part-load operation, lower temperatures and pressures are reached in the CVVT Engine, which imply lower mechanical stresses that favor engine lifetime. It also represents a potential for additional efficiency enhancement via increasing combustion temperature. Finally, a fuel economy estimation analysis is carried out to provide quantitative assessment about the economic advantage of the proposed CVVT Engine. From this analysis, a fuel economy increment of up to 4.1% is obtained for a CVVT Engine with respect to a Throttled Engine at a 20%–30% load, which is typical of a real vehicle engine operation.

Experimental study on the diesel and biodiesel spray characteristics emerging from equilateral triangular orifice under real diesel engine operation conditions

The triangular spray has a potential to accelerate air-fuel mixing rate and undergo axis-switching during the injection process, which both are beneficial for improving the atomization quality. This paper presents an experimental investigation on the macro-spray characteristics and the mechanism of axis-switching with diesel and biodiesel emerging from equilateral triangular orifice of diesel nozzle, by using shadowgraph technique, under various injection pressures (50 MPa, 70 MPa, 90 MPa) and backpressures (1 MPa, 2 MPa, 3 MPa). Two CCD cameras were set to capture the macro spray images at the minor and major view planes simultaneously. Macro spray characteristics values were processed from the spray images in different view planes by MATLAB. The results indicated that the spray width of biodiesel was larger than that of diesel at all conditions from all view planes. In addition, both diesel and biodiesel emerging from equilateral triangular orifice underwent axis-switching during the spray progress even under the typical diesel engine operation conditions. Moreover, the difference of equilateral triangular spray widths between minor plane and major plane decreases as the backpressure increases for both fuels, it is expected that the increasing of backpressure enhances the aerodynamic effects, resulting in inhibiting the spray axis-switching. Furthermore, the difference of diesel spray widths between the major plane and minor plane was much higher than that of biodiesel. Because the higher surface tension and viscosity of biodiesel can cause smaller surface-instabilities and also resist the spray deformation, which are conductive to suppress the biodiesel spray axis-switching, and thus ultimately lead to narrowing the difference of biodiesel spray widths between minor plane and major plane. Finally, the spray tip penetration of biodiesel was consistent longer than that of diesel, while the spray cone angle of biodiesel was smaller than that of diesel, and also there was an interaction between major and minor view planes for diesel spray cone angle values at the backpressure of 1 MPa, but it didn’t happen for biodiesel during the whole injection process. The present results indicated that the diesel spray was much easier to undergo axis-switching. The higher probability of axis-switching, larger spray cone angle and spray width of diesel demonstrated better air-fuel mixing quality than biodiesel.

Low Cycle Fatigue Life Estimation and Tracking for Industrial Gas Turbine Blades Using Fatigue Factor Approach

Low cycle fatigue life consumption analysis was carried out in this work. Fatigue cycles accumulation method suitable even if engine is not often shut down was applied together with the modified universal sloped method for estimating fatigue cycles to failure. Damage summation rule was applied to estimate the fatigue damage accumulated over a given period of engine operation. The concept of fatigue factor which indicates how well engine is operated was introduced to make engine life tracking feasible. The developed fatigue life tracking method was incorporated in PYTHIA, Cranfield University in-house software and applied to 8 months of engine operation. The results obtained are similar to those of real engine operation. At a set power level, fatigue life decreases with increase in ambient temperature with the magnitude of decrease greater at higher power levels. The fatigue life tracking methodology developed could serve as a useful tool to engine operators.

Creep-Fatigue Interaction Life Consumption of Industrial Gas Turbine Blades

This paper presents the creep-fatigue interaction life consumption of industrial gas turbine blades using the LM2500+ engine operated at Pulrose Power station, Isle of Mann as a case study. The linear damage summation approach where creep damage and fatigue damage are combined was used for the creep-fatigue interaction life consumption of the target blades. The creep damage was modelled with the Larson-Miller parameter method while fatigue damage was assessed with the modified universal slopes method and the damage due to creep-fatigue interaction was obtained from the respective life fractions. Because of the difficulty in predicting the life of engine components accurately, relative life consumption analysis was carried out in the work using the concept of creep-fatigue interaction factor which is the ratio of the creep-fatigue interaction life obtained from any condition of engine operation to a reference creep-fatigue interaction life. The developed creep-fatigue interaction life consumption analysis procedure was applied to 8 most of real engine operation. It was observed that the contribution of creep to creep-fatigue interaction life consumption is greater than that of fatigue at all ambient temperatures. The fatigue contribution is greater at lower ambient temperatures as against higher ambient temperatures. For the case study, the overall equivalent creep-fatigue factor obtained was 1.5 which indicates safe engine operation compared to the reference condition. The developed life analysis algorithm could be applied to other engines and could serve as useful tool in engine life monitoring by engine operators.