The Ultra Compact Combustor (UCC) is an innovative combustor system alternative to traditional turbine engine combustors with the potential for engine efficiency improvements with a reduced volume. Historically, the UCC cavity had been configured such that highly centrifugally loaded combustion took place in a recessed circumferential cavity positioned around the outside diameter of the engine. One of the obstacles with this design was that the combustion products had to migrate radially across the span of a vane while being pushed downstream by a central core flow. This configuration proved difficult to produce a uniform temperature distribution at the first turbine rotor. The present study has taken a different spin on the implementation of circumferential combustion. Namely, it aims to combine the combustion and space saving benefits of the highly centrifugally loaded combustion of the UCC in a new combustor orientation that places the combustor axially upstream of the turbine versus radially outboard. An iterative design approach was used to computationally analyze this new geometry configuration with the goal of fitting within the casing of a JetCat P90RXi. This investigation revealed techniques for implementation of this concept including small-scale combustor centrifugal air loading development, maintaining combustor circumferential swirl, combustion stability, and fuel distribution are reported. Furthermore, dramatic improvements in the uniformity of the turbine inlet temperature profiles are revealed over historical UCC concepts.

Oil-lubricated bearings are widely used in high speed rotating machines such as those found in the aerospace and automotive industries. However, environmental issues and risk-averse operations are resulting in the removal of oil and the replacement of all sealed oil bearings with reliable water-lubricated bearings. Due to the different fluid properties between oil and water, the low viscosity of water increases Reynolds numbers drastically and therefore makes water-lubricated bearings prone to turbulence effects. This requires finer meshes when compared to oil-lubricated bearings as the low-viscosity fluid produces a very thin lubricant film. Analyzing water-lubricated bearings can also produce convergence and accuracy issues in traditional oil-based analysis codes. Thermal deformation largely affects oil-lubricated bearings, while having limited effects on water lubrication; mechanical deformation largely affects water lubrication, while its effects are typically lower than thermal deformation with oil. One common turbulence model used in these analysis tools is the eddy-viscosity model. Eddy-viscosity depends on the wall shear stress, therefore effective wall shear stress modeling is necessary in determining an appropriate turbulence model. Improving the accuracy and efficiency of modeling approaches for eddy-viscosity in turbulence models is of great importance. Therefore, the purpose of this study is to perform mesh refinement for water-lubricated bearings based on methodologies of eddy-viscosity modeling to improve their accuracy. According to Szeri [1], ε m /v for the Boussinesq hypothesis is given by Reichardt’s formula. Fitting the velocity profile with experiments having a y + in the range of 0–1,000 results in Ng-optimized Reichardt’s constants k = 0.4 and δ + = 10.7. He clearly states that for y + > 1000 theoretical predictions and experiments have a greater variance. Armentrout and others [2] developed an equation for δ + as a function of the pivot Reynolds number, which they validated with CFD simulations. The definition of y + can be used to approximate the first layer thickness calculated for a uniform mesh. Together with Armentrout’s equation, the number of required elements across the film thickness can be obtained. For typical turbulence models, the y + must be within a certain range to be accurate. On the condition that the y + is fixed to that of a standard oil bearing for which an oil bearing code was validated, the number of elements across the film thickness and coefficients used in the eddy-viscosity equation can be adjusted to allow for convergence with other fluids other than that which the traditional oil bearing code was designed for. In this study, the number of required elements across the film for improved prediction quality was calculated based on the proposed eddy-viscosity model mesh correction from the known literature. A comparison between water lubrication using the parameter correction and oil lubrication was also made. The results of this study could aid in improving future designs and models of water-lubricated bearings.

Experimental data describing laminar separation bubbles developing under strong adverse pressure gradients, typical of Ultra-High-Lift turbine blades, have been analyzed to define empirical correlations able to predict the main features of the separated flow transition. Tests have been performed for three different Reynolds numbers and three different free-stream turbulence intensity levels. For each condition, around 4000 Particle Image Velocimetry (PIV) snapshots have been acquired. A wavelet based intermittency detection technique, able to identify the large scale vortices shed as a consequence of the separation, has been applied to the large amount of data to efficiently compute the intermittency function for the different conditions. The transition onset and end positions, as well as the turbulent spot production rate are evaluated. Thanks to the recent advancements in the understanding on the role played by Reynolds number and free-stream turbulence intensity on the dynamics leading to transition in separated flows, guest functions are proposed in the paper to fit the data. The proposed functions are able to mimic the effects of Reynolds number and free-stream turbulence intensity level on the receptivity process of the boundary layer in the attached part, on the disturbance exponential growth rate observed in the linear stability region of the separated shear layer, as well as on the nonlinear later stage of completing transition. Once identified the structure of the correlation functions, a fitting process with own and literature data allowed us to calibrate the unknown constants. Results reported in the paper show the ability of the proposed correlations to adequately predict the transition process in the case of separated flows. The correlation for the spot production rate here proposed extends the correlations proposed in liter-ature for attached (by-pass like) transition process, and could be used in γ–Re ϑ codes, where the spot production rate appears as a source term in the intermittency function transport equation.

This paper presents in detail the improved streamline curvature approach (SLC) to the performance evaluation and internal flow field calculation of subsonic and transonic axial compressors. Based on previous research, the diverse incidence, deviation and total pressure loss models, generally existing in the form of fitting curves and semi-empirical correlations, are discussed respectively. Typically, transonic flow in axial compressor results in the variation of several flow parameters and particularly the appearance of shock waves compared with subsonic flow. In this paper, the revision and improvement of loss models are applied to reach higher accuracy, especially considering the loss component due to actual incidence angle. Several modifications have been made as well considering the influence of three-dimensional flow. For the purpose of validating this approach, two test cases, including a single-stage transonic axial compressor NASA Stage37 and a 3-stage subsonic axial compressor P&W 3S1, are calculated. The overall characteristics and spanwise aerodynamic parameters for blade rows are demonstrated at both design and off-design conditions. Furthermore, the results agree well with both experimental data and computational fluid dynamic (CFD) results. This throughflow method is verified as an applicable and convenient tool for aerodynamic analysis and performance prediction of subsonic and transonic axial compressors.

The requirements for cleaner energy have driven industrial gas turbines manufacturers to increase firing temperatures and improve cooling of nozzles. The application of high temperature alloys having adequate thermo-mechanical requirements is critical, as assessed by low cycle fatigue performance. The effect of higher firing temperatures combined with higher cooling efficiencies has lead to operating cycles where the level of plastic strain imparted define component life. The capability of material models to account for non-linear effects such as ratchetting or shakedown, cyclic hardening or softening as well as Bauschinger or relaxation effects have been highlighted in this context. Neglecting these effects can lead to over and under-conservative life assessment analysis, while accounting for them using standard multilinear material models lead to convergence issues in finite element analysis. In this paper, Chaboche viscoplastic model has been applied to a transient structural of a first stage gas turbine nozzle. Fitting of the model based on experimental mechanical test data on MAR-M-247 alloy will be described, followed by an overview of how the model may be implemented to a benchmark nozzle thermo-mechanical transient analysis. Finally the details how the Chaboche-type model has provided up to 50% decrease in computation time when compared to using a standard multi-linear material modelling approach.

Maintenance costs are a substantial contributor to airline operating costs. In this context, understanding, analyzing, and predicting engine performance deterioration is crucial. While diagnostic methods for analyzing the current module and overall engine condition are established in state-of-the-art engine condition monitoring (ECM) systems, deterioration modeling and prognosis are still fields of research. The identification of the contribution of deterioration mechanisms, such as fouling, erosion, and abrasion, to the in-service deterioration poses a key challenge in this area. This paper focuses on a top-down approach for the high pressure compressor (HPC) module. The selected approach is to quantify the contribution of individual deterioration mechanisms to the overall HPC efficiency deterioration based on in-flight measurements. This is accomplished by first using the in-flight measurements to analyze the HPC efficiency loss. Then, the resulting time series of the analyzed HPC efficiency loss are preprocessed. Finally, models of the deterioration mechanisms are fitted to the preprocessed time series. The deterioration models are chosen based on literature references to the respective deterioration mechanisms. As multiple influencing factors affect the deterioration mechanisms, a fleet analysis is conducted to select the model inputs. The fitting process involves a parametric nonlinear regression problem. The outcome is an estimation of the evolution of the deterioration mechanisms over time. This methodology is used to evaluate all available in-service engines of the same type and fleet and to define a fleet model. In the final step, benefits and limitations of the fleet model are investigated.

In this paper, we present a method to determine the quantitative stability level of a lean-premixed combustor from dynamic pressure data. Specifically, we make use of the autocorrelation function of the dynamic pressure signal acquired in a combustor where a turbulent flame acts as a thermoacoustic driver. In the proposed approach, the unfiltered pressure signal including several modes is analyzed by an algorithm based on Bayesian statistics. For this purpose, a Gibbs sampler is used to calculate parameters like damping rates and eigenfrequencies in the form of probability density functions (PDF) by a Markov-Chain Monte-Carlo (MCMC) method. The method provides a robust solution algorithm for fitting problems without requiring initial values. A further advantage lies in the nature of the statistical approach since the results can be assessed regarding its quality by means of the PDF and its standard deviation for each of the obtained parameters. First, a simulation of a stochastically forced van-der-Pol oscillator with pre-set input values is carried out to demonstrate accuracy and robustness of the method. In this context it is shown that, despite of a large amount of uncorrelated background noise, the identified damping rates are in a good agreement with the simulated parameters. Secondly, this technique is applied to measured pressure data. By doing so, the combustor is initially operated under stable conditions before the thermal power is gradually increased by adjusting the fuel mass flow rate until a limit-cycle oscillation is established. It is found that the obtained damping rates are qualitatively in line with the amplitude levels observed during operation of the combustor.

This paper presents a set of methodologies for the extraction of linear growth and damping rates associated with transversal eigenmodes at screech level frequencies in thermoacoustically non-compact gas turbine combustion systems from time domain data. Knowledge of these quantities is of high technical relevance as an required input for the design of damping devices for high frequency oscillations. In addition, validation of prediction tools and flame models as well as the thermoacoustic characterization of a given unstable/stable operation point in terms of their distance from the Hopf bifurcation point occurs via the system growth/damping rates. The methodologies solely rely on dynamic measurement data (i.e. unsteady heat release and/or pressure recordings) while avoiding the need of any external excitation (e.g. via sirens), and are thus in principle suitable for the employment on operational engine data. Specifically, the following methodologies are presented: 1) The extraction of pure acoustic damping rates (i.e. without any flame contribution) from oscillatory chemiluminescence and pressure recordings. 2) The obtainment of net growth rates of linearly stable operation points from oscillatory pressure signals. 3) The identification of net growth rates of linearly unstable operation points from noisy pressure envelope data. The fundamental basis of these procedures is the derivation of appropriate stochastic differential equations, which admit analytical solutions that depend on the global system parameters. These analytical expressions serve as objective functions against which measured data are fitted to yield the desired growth or damping rates. Bayesian methods are employed to optimize precision and confidence of the fitting results. Numerical test cases given by time domain formulations of the acoustic conservation equations including high-frequency flame models as well as acoustic damping terms are set up and solved. The resulting unsteady pressure and heat release data are then subjected to the proposed identification methodologies to present corresponding proof of principles and grant suitability for employment on real systems.

Recent experimental work from the present authors demonstrated that interactions between the mainstream and cavity/rim seal flows lead to ingestion mechanisms with a range of length scales. In addition to the (well known) effect of the vane and blade pressure fields, it was demonstrated that the shear layer instabilities between the mainstream and rim seal flows can affect ingress. Building upon these observations and the understanding in the literature, this paper presents a model which relates rotor-stator cavity seal effectiveness to purge flow rate based on turbulent transport. The main assumption is that all length scales of ingress lead to an effective eddy diffusivity. This eddy diffusivity drives ingress across the seal concentration gradient. Following Prandtl’s mixing length hypothesis for eddy viscosity, the model uses an empirical constant representing an equivalent mixing length. This assumption is shown to be sufficient across a limited range of dimensionless flow rates. An extension of the model is presented to account for the reduction in turbulent mixing in the rim seal recirculation region as it becomes washed out with increasing purge flow. The rate at which the effect of the rim seal recirculation region gets washed out is modelled with a purge-to-mainstream blowing ratio term and the volume fraction of the seal occupied by the rim seal recirculation. The differences in volume fraction and blowing ratio between the different experiments in literature are defined by the geometry and flow condition only. By fitting, it is shown that the model is sufficient to capture a wide variety of experimental data in the literature and that of the present authors. The results and the model derivation provide an encouraging first step and a framework towards a model that is sensitized to both geometry and flow conditions.

Although the research in non-intrusive techniques for the measurement of vibration have made major progress since the beginning in the 1960’s, they are still mainly used as additional tool to the common strain gauges. Therefore, there is still a great deal of interest in the improvement of such non-contact vibration measurement techniques, to replace the intrusive ones with alternative techniques. One possibility to monitor all blades at once is blade tip-timing. The probes for a blade tip-timing measurement system are mounted circumferentially in the engine casing to log the passing times of the rotor blades. These logged time data will be compared with theoretically calculated passing times. The deviation between measured and calculated passing times can be transformed to blade displacement values. In recent years, several methods to analyse the acquired vibration data have been developed and improved. They are directed to evaluate synchronous and asynchronous blade vibration events. This paper focuses on the identification of asynchronous vibrations on rotor blades using blade tip-timing. Taking the data from all probes into account gives an opportunity to determine the vibration of each single blade. Due to the usage of a research test rig, all measurement data could be acquired in simulated real case operation scenarios. Analysis data were evaluated with a developed post processing routine based on a Fourier transformation algorithm coupled with a least square fitting procedure. Since compressor surge represents one of the most critical non synchronous events during compressor operation, in this paper a special interest is paid to the analysis of compressor surges. Vibration frequencies revealed during surge investigation will be compared with simultaneously measured strain gauge data to ensure the reliability of blade tip-timing measurement and analysis. To explain the results in more detail, the possibility of a blade damaged triggered shift of the blade characteristic frequency is shown. The most promising result of the analysis is the close correlation between the identified vibration frequencies of compressor surge events and the afterwards determined frequency mistuning and crack distributions. Blade damage becomes visible through increasing deviation between characteristic frequencies of different blades as result of multiple surge events. In addition, with the comparison of mean frequency records over each single surge among each other it is possible to restrict the blade damage time. Subsequently, the possibility to develop a process routine to predict blade damage during compressor test series could arise.

Generally, turbine blade vibration can be divided into asynchronous vibration and synchronous vibration. Comparing to parameters identification of asynchronous vibration, that of the synchronous vibration is more difficult and needs more sensors. The applicability of the synchronous identification method is more stringent than that of asynchronous identification method. A new method is presented to identify the blade synchronous vibration parameters based on the blade tip-timing (BTT) method and previous achievements in this region. Here, the parameters, such as the frequency of harmonic resonance center, blade vibration amplitude and the initial phase, are obtained by the nonlinear least square fitting algorithm based on relationships between the rotation speed and the blade tip displacement. We call this way as sweep frequency fitting (SFF) method. As the blade is operated at a constant speed that is near the frequency of resonance center, the blade vibration displacement can be obtained by the sensors at different positions, so the blade synchronous vibration Engine Order (EO) can be obtained by the global autoregressive with instrumental variables (GARIV) method. Furthermore the Campbell diagram of blade synchronous vibration can be plotted by the parameters obtained by GARIV method and SFF method. In the experimental study, the parameter identification of blade synchronous vibration is completed and the Campbell diagram of blade vibration is accurately plotted under the excitation of six magnets. Meanwhile, the experimental study and analysis on the harmonic vibration of blade with different numbers of excitation are carried out. The relative deviation of the dynamic frequency of blade between the experimental result and simulation result is less than 1%.

The combined high and low cycle fatigue (CCF) test on full scale turbine blade in the laboratory is an important method to evaluate the life. In fact, the low cycle fatigue which is usually caused by the centrifugal force can be confirmed easily. While, the high cycle fatigue which is usually caused by the vibration and aerodynamic force is often hard to determine. So the previous scholar has proposed the contrast method to determine the high cycle load in the field. This method utilizes the new and used blades to determine the high cycle within certain limits. While it can’t be applied effectively in the whole life range with the low cycle-high cycle-ultra high cycle fatigue theory raised. So this paper put forward the modified contrast method to realize the optimization. Firstly, the CCF tests are carried out on the turbine blade systematically. Then, the CCF damage properties, including the crack propagation, the fracture morphology and the dynamic characteristic are analyzed. Lastly, the new modified contrast method is proposed with the new coordinate axes, new fitting criterions and amend method. Through comparisons we conclude that: the new method is slightly complicated, but the evaluate precision has significantly increased. So it could be used to deal with data for CCF tests on full scale turbine blade in the future.

The anisotropy is the most remarkable characteristic for single crystal nickel-based superalloys, which makes fatigue behavior and life prediction highly correlate with the crystallographic orientation. Based on critical plane approach and preferred crystallographic slip mechanism, an anisotropic LCF life model is proposed to account for orientation-dependent fatigue life in this paper. In addition, the effects of the mean stress and stress-weakening caused by asymmetric loading are also considered. The critical plane is determined by searching for 30 potential slip systems. Moreover, the slip plane with the maximum resolved shear stress amplitude in the crystallographic microstructure of the single crystal nickel-based superalloy is chosen as the critical plane. The LCF test data are utilized to obtain the regression equation by multiple linear fitting method. The presented LCF life model is applicable for more complex stress state and has higher prediction accuracy than the CDY model.

An experimental investigation of the influence of dampers on the stability margin of an atmospheric lab-scale annular combustor is presented. The rig allows the comparison of different damper configurations regarding the number of dampers, their spatial distribution and the amount of purge air used for temperature control. The porosity of the perforated plates at the damper exits as well as the influence of the purge air are systematically investigated. Eigenfrequencies and damping rates are computed from the acoustic pressures measured in the combustor with three different methods: The first method is based on the analysis of the decay of the pulsating pressures after sudden shut-down of sirens providing single frequency acoustic excitation. The second method employs Lorentzian fitting to the pressure spectra resulting from turbulent combustion noise and the third method consists of the analysis of the autocorrelation of the acoustic pressures. Since with all three methods very similar eigenfrequencies and damping rates are obtained for the reference configuration without dampers the more complicated first method with forcing does not exhibit advantages over the simpler two other methods, which analyze the acoustic response of the combustor to turbulent combustion noise. As expected, adding dampers leads to a significant increase of the damping rate, but surprisingly the magnitude of this increase depends on the evaluation method employed. Because of the deterioration of the quality of Lorentzian fitting it cannot be applied in cases with strong damper influence. Furthermore, the forcing needed for the decay method induces hot gas ingestion in the dampers leading to detuning. This means that this method modifies the system to be diagnosed and that the results obtained characterize the case with over-temperature in the dampers, which is not representative for normal combustor operation. In conclusion, best results are obtained with the simple autocorrelation method. Pressure data analysis reveals that combustor damping increases with porosity and purge air mass flow rate.

In this paper, common faults in main components of industrial three-shaft gas turbine are simulated through the nonlinear steady-state model, and the effects of these faults on the performance of all five main components and main measurement parameters are analyzed in both part and full load. Meanwhile, the sensitivity of these parameters to the location and type of fault and the fault severity in both part and full load is analyzed. In this study, in order to improve the accuracy of the non-linear steady-state model, the variable specific heat is considered with fitting formulas. In this model, the faults simulation is performed by changing the flow capacity and isentropic efficiency of each component via modification of the compressors and turbines characteristic curve. Meanwhile, a Genetic Algorithm (GA) based non-linear gas turbine steady-state performance simulation approach has been presented to best estimate the unknown component parameters. The fault simulation results in both part and full-load conditions indicate that by increasing the faults severity, the component performance parameters and the measurement parameters will deviate almost linearly from clean condition. Moreover, the sensitivity of these parameters varies with the location and type of the fault and also varies with the operating condition. Therefore, it can be used as the basis for selection of key parameters to identify the location and type of the fault. Furthermore, it also shows that considering the effects of load variations in design of a gas turbine diagnosis system is needed.

The aerodynamic performance and noise of the blade are two important aspects which people pay much attention nowadays in the design of turbine machinery such as centrifugal fan and axial flow fan. In this paper, the three-dimensional model of the long-eared owl wing is established based on the section theory and fitting formula firstly. And then, unsteady aerodynamic and acoustic characteristics of the bionic blade are numerically investigated using Large-Eddy Simulation (LES) and the Ffowcs Williams-Hawkings (FW-H) equation based on Lighthill’s acoustic theory. The results indicate that the deeply concaved lower surface near the wing root plays a significant role in improving the lift-to-drag ratio. The lift coefficient and drag coefficient of the bionic blade is analyzed by comparing two-dimensional and three-dimensional results. The cross section profiles near the wing root possess the larger lift coefficients and the lesser drag coefficients, even than the three-dimensional long-eared owl wing. The size of the separation bubble grows at increasing angle of attack. The 40% cross-section profile of the long-eared owl wing could increase the distance between the corresponding vortex centers with wall surface thus reducing the range of the vortex shedding near the wall effectively. The iso-Q surfaces show that the location of the vortex shedding and the movement of separation bubble. When the angle of attack α is 5°, the aerodynamic noise generated by the bionic blade is lower than in other angle of attack condition. The minimum value of the sound pressure level (SPL) is even 17.9dB on the y-direction. In the range of 5°–15°, the strength and size of the vortex motion increase with the increase of the angle of attack. The far-field noise suggests the directivities of dipole noise. The range of the separation bubbles act as the most influence of the noise generation. The sound pressure level (SPL) of bionic blade at α = 5° is less than other conditions and the minimum value is even 17.9dB. The thin airfoil near the wingtip could decrease the pressure fluctuation from the blade surface that can reduce the unsteady aerodynamic noise. It means the unique structure of the long-eared owl wing can suppresses the unsteady pressure fluctuation on the surface which could decrease the noise generated by the wing surface.

This work newly proposes an uncertainty quantification method named SAMBA PC (Sparse Approximation of Moment-Based Arbitrary Polynomial Chaos) that offers a single solution to many current problems in turbomachinery applications. At the moment every specific case is characterized by a variety of different input types such as histograms (from experimental data), normal PDFs (design rules) or fat tailed PDFs (for rare events). Thus, the application of UQ requires the adaptation of ad hoc methods for each individual case. A second problem is that parametric PDFs have to be determined for all inputs. This is difficult if only few samples are available. In gas turbines, however, the collection of statistical information is difficult, expensive and having scarce information is the norm. A third critical limitation is that if using Non-Intrusive Polynomial Chaos methods the number of required simulations grows exponentially with increasing numbers of input uncertainties: the so-called ‘curse of dimensionality’. In this work it is shown that the fitting of parametric PDFs to small data sets can lead to large bias and the direct use of the available data is more accurate. This is done by propagating uncertainty through several test functions and the CFD simulation of a diffuser, highlighting the impact of different PDF fittings on the output. From the results it is concluded that the direct propagation of the experimental data set is preferable to the fit of parametric distributions if data is scarce. Thus, the suggested method offers an alternative to the maximum entropy theorem to handle scarce data. SAMBA simplifies the mathematical procedure for many different input types by basing the polynomial expansion on moments. Its moment-based expansion automatically takes care of arbitrary combinations of different input data. SAMBA is also numerically efficient compared to other UQ implementations. The relationship between the number of random variables and number of simulation is linear (only 21 simulations for 10 input random variables are required). It is shown that SAMBA’s algorithm can propagate a high number of input distributions through a set of nonlinear analytic test functions. Doing this the code needs a very small number of simulations and preserves a 5% error margin. SAMBA’s flexibility to handle different forms of input distributions and a high number of input variables is shown on a low pressure turbine blade based on H2 profile. The relative importance of manufacturing errors in different location of the blade is analyzed.

Market requests for higher performance fans and legal requirements to meet minimum efficiency grades drive industrial fan designers for tunnel and metro applications to study or re-think stall control solutions. This paper, therefore, focuses on how anti-stall rings work and provides a robust and fast numerical methodology to evaluate and improve their efficiency and effectiveness. Here we present a numerical study validated against available experiments on the fitting of an anti-stall ring on an axial fan for tunnel and metro operations. The study synthetizes the effects of the anti-stall ring with an actuator disk coupled to a frozen rotor model for the fan, significantly reducing the computational load required and validating the methodology. Such approach can be implemented to easily derive fan performance with different geometries of the anti-stall ring plenum as well as its fins.

Blade curvature has an important effect on the pressure distribution over the blade surface as well as the quality of airfoil machining, but curvature smoothing method in design environments is little studied. A new geometry generator is developed for the design of curvature-smooth airfoils. The sections of an airfoil can be initially designed by a conventional method, and each of the sections is then regenerated by fitting a fifth order B-spline curve. The first order differential of the curvature with respect to arc length of the blade surface is used as a curvature smoothness measure. The distance between discrete points and the curve, and the integral of the square of the first derivative along the streamwise section curve are simultaneously minimized in the fitting process. The design of a transonic centrifugal compressor for turbocharger application is presented to study the effects of the curvature-smooth blade on centrifugal compressor performance. A numerical study was carried out and the results are discussed.

Operational availability and reliability have never been that high than on current single aisle aircraft engines, close to 100%. Engine Condition Monitoring (ECM) contributes to these good statistics and aims at making it even better. This engines generation will still be operated for at least twenty years. Meanwhile, new engine generation, with new monitoring capabilities, will enter into service within a couple of years. Regardless of engine generation, Operators’ expectations on operational availability and maintenance cost reduction will continue to grow. This statement leads to propose monitoring capability update for current engine generation. Historically powerplant monitoring was mainly dedicated to engine removal planning and full power demonstration. With time and product knowledge increase, usage of trend monitoring, on a restricted set of parameters, provided early warning detection capability to assess some systems health and identify line maintenance actions to preserve engine time on-wing. Unfortunately, legacy monitoring process does not take advantage of full avionics capabilities so that there is an opportunity to bring new monitoring functions on current engine fleet. Consequently, constraints for such Project are the adaptation of software without adding any sensor and fitting the existing operational process. New introduced functions will enable to monitor oil consumption, start capability, enhanced performances, sensors intermittency and control system. This paper describes, in a systemic approach, the implementation of the operational process, the adaptation of both embedded and ground system, the outcomes of the monitoring functions and finally the outcomes on the data and skill management on the customer support side. As a consequence, new services for new business can emerge in a new customer support paradigm.