scholarly journals Determination of Serviceability Limits of a Turboshaft Engine by the Criterion of Blade Natural Frequency and Stall Margin

Aerospace ◽  
2019 ◽  
Vol 6 (12) ◽  
pp. 132 ◽  
Author(s):  
Yaroslav Dvirnyk ◽  
Dmytro Pavlenko ◽  
Radoslaw Przysowa
Keyword(s):  
Axial Compressor ◽  
Operational Experience ◽  
Two Phase ◽  
Compressor Blades ◽  
Stall Margin ◽  
Wear Process ◽  
Engine Order ◽  
Gradual Loss ◽  
And Performance ◽  
Turboshaft Engine

This paper analyzes the health and performance of the 12-stage axial compressor of the TV3-117VM/VMA turboshaft operated in a desert environment. The results of the dimensional control of 4800 worn blades are analyzed to model the wear process. Operational experience and two-phase flow simulations are used to assess the effectiveness of an inlet particle separator. Numerical modal analysis is performed to generate the Campbell diagram of the worn blades and identify resonant blade vibrations which can lead to high cycle fatigue (HCF): mode 7 engine order 30 in the first stage and mode 8 engine order 60 in the fourth. It is also shown that the gradual loss of the stall margin over time determines the serviceability limits of compressor blades. In particular, the chord wear of sixth-stage blades as high as 6.19 mm results in a reduction of the stall margin by 15–17% and a permanent stall at 770–790 flight hours. In addition, recommendations setting out go/no-go criteria are made to maintenance and repair organizations.

scholarly journals Determination of Serviceability Limits of a Turboshaft Engine by the Criterion of Blade Natural Frequency and Stall Margin

2019 ◽  
Author(s):  
Yaroslav Dvirnyk ◽  
Dmytro Pavlenko ◽  
Radoslaw Przysowa
Keyword(s):  
Axial Compressor ◽  
Operational Experience ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Stall Margin ◽  
Wear Process ◽  
Gradual Loss ◽  
And Performance ◽  
Turboshaft Engine ◽  
Particle Separator

This paper analyses the health and performance of 12-stage axial compressor of the TV3-117VM/VMA turboshaft operated in a desert environment. The results of the dimensional control of 4,800 worn blades are analysed to model the wear process. Operational experience and numerical simulations are used to assess the effectiveness of an Inlet Particle Separator. Numerical modal analysis is performed to generate the Campbell diagram of worn blades and identify resonant blade vibration which can lead to high cycle fatigue (HCF). It is shown that the gradual loss of the stall margin over time determines the serviceability limits of compressor blades. Recommendations setting out go / no-go criteria are made to maintenance and repair organisations.

scholarly journals Determination of serviceability limits of a turboshaft engine by the criterion of blade natural frequency and stall margin

2019 ◽  
Vol 304 ◽  
pp. 03004
Author(s):  
Yaroslav Dvirnyk ◽  
Dmytro Pavlenko ◽  
Radoslaw Przysowa
Keyword(s):  
Axial Compressor ◽  
Operational Experience ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Stall Margin ◽  
Wear Process ◽  
Gradual Loss ◽  
And Performance ◽  
Turboshaft Engine ◽  
Particle Separator

This paper analyses the health and performance of 12–stage axial compressor of the TV3–117VM/VMA turboshaft operated in a desert environment. The results of the dimensional control of 4,800 worn blades are analysed to model the wear process. Operational experience is used to assess the effectiveness of an Inlet Particle Separator. Numerical modal analysis is performed to generate the Campbell diagram of worn blades and identify resonant blade vibration which can lead to high cycle fatigue (HCF). It is shown that the gradual loss of the stall margin over time determines the serviceability limits of compressor blades. Recommendations setting out go / no–go criteria are made to maintenance and repair organisations.

scholarly journals Non-Contact Measurement of Blade Vibration in an Axial Compressor

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 68 ◽  
Author(s):  
Radoslaw Przysowa ◽  
Peter Russhard
Keyword(s):  
Axial Compressor ◽  
Rotating Stall ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Work Related ◽  
Higher Order Modes ◽  
Pearson Coefficient ◽  
Engine Order ◽  
Simultaneous Resonances ◽  
Timing System

Complex blade responses such as a rotating stall or simultaneous resonances are common in modern engines and their observation can be a challenge even for state-of-the-art tip-timing systems and trained operators. This paper analyses forced vibrations of axial compressor blades, measured during the bench tests of the SO-3 turbojet. In relation to earlier studies conducted in Poland with a small number of sensors, a multichannel tip-timing system let us observe simultaneous responses or higher-order modes. To find possible symptoms of a failure, blade responses in a healthy and unhealthy engine configuration with an inlet blocker were studied. The used analysis methods covered all-blade spectrum and the circumferential fitting of blade deflections to the harmonic oscillator model. The Pearson coefficient of correlation between the measured and predicted tip deflection is calculated to evaluate fitting results. It helps to avoid common operator mistakes and misinterpreting the results. The proposed modal solver can track the vibration frequency and adjust the engine order on the fly. That way, synchronous and asynchronous vibrations are observed and analysed together with an extended variant of least squares. This approach saves a lot of work related to configuring the conventional tip-timing solver.

A CFD Study of Circumferential Groove Casing Treatments in a Transonic Axial Compressor

2010 ◽  
Author(s):  
Haixin Chen ◽  
Xudong Huang ◽  
Ke Shi ◽  
Song Fu ◽  
Matthew A. Bennington ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Data Sampling ◽  
Stall Margin ◽  
Casing Treatment ◽  
Circumferential Groove ◽  
Compressor Rotor ◽  
Radial Profiles ◽  
Flow Mechanisms ◽  
Transonic Axial Compressor ◽  
And Performance

Numerical investigations were conducted to predict the performance of a transonic axial compressor rotor with circumferential groove casing treatment. The Notre Dame Transonic Axial Compressor (ND-TAC) was simulated by Tsinghua University with an in-house CFD code (NSAWET) for this work. Experimental data from the ND-TAC were used to define the geometry, boundary conditions and data sampling method for the numerical simulation. These efforts, combined with several unique simulation approaches, such as non-matched grid boundary technology to treat the periodic boundaries and interfaces between groove grids and the passage grid, resulted in good agreement between the numerical and experimental results for overall compressor performance and radial profiles of exit total pressure. Efforts were made to study blade level flow mechanisms to determine how the casing treatment impacts the compressor’s stall margin and performance. The flow structures in the passage, the tip gap and the grooves as well as their mutual interactions were plotted and analyzed. The flow and momentum transport across the tip gap in the smooth wall and the casing treatment configurations were quantitatively compared.

Effects of Blade Damage on the Performance of a Transonic Axial Compressor Rotor

2012 ◽  
Author(s):  
Yanling Li ◽  
Abdulnaser Sayma
Keyword(s):  
Axial Compressor ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Design Stage ◽  
Compressor Blades ◽  
Stall Margin ◽  
Compressor Rotor ◽  
Surge Margin ◽  
Compressor Performance ◽  
Transonic Axial Compressor

Gas turbine axial compressor blades may encounter damage during service for various reasons. Debris from casing or foreign objects may impact blades causing damage near the rotor’s tip. This may result in deterioration of performance and reduction in the surge margin. Ability to assess the effect of damaged blades on the compressor performance and stability is important at both the design stage and in service. The damage to compressor blades breaks the cyclic symmetry of the compressor assembly. Thus computations have to be performed using the whole annulus. Moreover, if rotating stall or surge occurs, the downstream boundary conditions are not known and simulations become difficult. This paper presents an unsteady CFD analysis of compressor performance with tip curl damage. Tip curl damage typically occurs when rotor blades hit a loose casing liner. The computations were performed up to the stall boundary, predicting rotating stall patterns. The aim is to assess the effect of blade damage on stall margin and provide better understanding of the flow behaviour during rotating stall. Computations for the undamaged rotor are also performed for comparison. A transonic axial compressor rotor is used for the time-accurate numerical unsteady flow simulations, with a variable choked nozzle downstream simulating an experimental throttle. One damaged blade was introduced in the rotor assembly and computations were performed at 60% of the design rotational speed. It was found that there is no significant effect on the compressor stall margin due to one damaged blade despite the differences in rotating stall patterns between the undamaged and damaged assemblies.

Flow and Performance Calculations of Axial Compressor near Stall Margin

2010 ◽  
Author(s):  
Yoojun Hwang ◽  
Shin-Hyoung Kang ◽  
M. A. Wahid ◽  
S. Samion ◽  
N. A. C. Sidik ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Stall Margin ◽  
And Performance

scholarly journals Evaluation of water washing efficiency and erosion risk in an axial compressor for different water injection conditions

2021 ◽  
Vol 312 ◽  
pp. 11008
Author(s):  
Giuliano Agati ◽  
Francesca Di Gruttola ◽  
Serena Gabriele ◽  
Domenico Simone ◽  
Paolo Venturini ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Normal Load ◽  
Droplet Diameter ◽  
Axial Compressor ◽  
Two Phase ◽  
Compressor Blades ◽  
Erosion Risk ◽  
Water Washing ◽  
Washing Efficiency ◽  
The Impact

Gas turbines performance losses are mainly due to the deposition of dirt on the compressor blades that needs to be periodically removed. This is the reason motivating the presence of water washing systems (WWS) in most of the compressor gas turbines. Water washing is generally achieved by installing a number of nozzles on the compressor casing and spraying water that clean the dirty surfaces of the compressor. The side effect of such a technique is the rising risk of erosion due to the impact of water droplets on the compressor blades which is even more pronounced when dealing with online water washing systems that is done while the unit is at normal load. The design of these systems must balance benefits and disadvantages associated to the process itself. The benefits can be measured in terms of water washing efficiency that is a quantity not uniquely defined. In previous works, the authors introduced some indices useful to evaluate the spatial cleaning coverage (the wet to the total surface) and the quantity of water mass actually impacting the dirty surfaces (the impacted to injected mass). On the other hand, water washing erosion is a complex phenomenon depending on several parameters, such as the mechanical properties of the blade material, the impact velocity and angle and the droplet diameter. For this reason, the WWS are strongly influenced by the adopted nozzles and by the injection conditions. The present paper aims at assessing water washing for six different injection conditions in the first stage of a real axial compressor. Two-phase CFD simulations are carried out with Ansys Fluent where a User Defined Function implemented by the authors is used to properly model water droplet erosion mechanism and to obtain all the quantities needed to evaluate the washing quality. Results confirm the strong influence of the injection conditions on the main features of the washing system. The study is part of an ongoing partnership between Baker Hughes and Sapienza University of Rome aiming at maximizing the washing of the compressor blades while maintaining the erosion under specific thresholds.

scholarly journals Non-Contact Measurement of Blade Vibration in an Axial Compressor

2019 ◽  
Author(s):  
Radoslaw Przysowa ◽  
Peter Russhard
Keyword(s):  
State Of The Art ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Compressor Blades ◽  
Blade Vibration ◽  
Work Related ◽  
Higher Order Modes ◽  
Engine Order ◽  
Simultaneous Resonances ◽  
Timing System

Complex blade responses such as a rotating stall or simultaneous resonances are common in modern engines and their observation can be a challenge even for state-of-the-art tip-timing systems and trained operators. This paper analyses forced vibrations of axial compressor blades, measured during the bench tests of the SO-3 turbojet. In relation to earlier studies conducted in ITWL with a small number of sensors, a multichannel tip-timing system let us observe simultaneous responses or higher-order modes. To find possible symptoms of a failure, blade responses in a healthy and unhealthy engine configuration with an inlet blocker were studied. The used analysis methods covered all-blade spectrum and the circumferential fitting of blade deflections to the harmonic oscillator model. The proposed modal solver can track the vibration frequency and adjust the engine order on the fly. That way, synchronous and asynchronous vibrations are observed and analysed together with an extended variant of least squares. The proposed approach helps to avoid common mistakes and saves a lot of work related to configuring the conventional solver.

Effects of Flow Control on Forced Response and Performance of a Transonic Compressor

2002 ◽  
Author(s):  
S. Todd Bailie ◽  
Wing F. Ng ◽  
Alfred L. Wicks ◽  
William W. Copenhaver
Keyword(s):  
Flow Control ◽  
Rotor Blade ◽  
Forced Response ◽  
Strain Gages ◽  
Complex Flow ◽  
Compressor Blades ◽  
Transonic Compressor ◽  
Engine Order ◽  
Blade Vibrations ◽  
And Performance

The main contributor to the high-cycle fatigue of compressor blades is the response to aerodynamic forcing functions generated by an upstream row of stators or inlet guide vanes. Resonant response to engine order excitation at certain rotor speeds is especially damaging. Studies have shown that flow control by trailing edge blowing (TEB) can reduce stator wake strength and the amplitude of the downstream rotor blade vibrations generated by the unsteady stator-rotor interaction. In the present study, the effectiveness of TEB to reduce forced blade vibrations was evaluated in a modern transonic compressor rig. A row of wake generator (WG) vanes with TEB capability was installed upstream of the rotor, which was instrumented with strain gages. Data was collected with and without TEB at various rotor speeds involving resonance crossings. Using 0.8% of the compressor core flow for TEB along the full WG-span, rotor blade strain was reduced by 66% at the first torsional resonance crossing. Substantial reductions were also achieved with only partial span TEB. The results demonstrate the effectiveness of the TEB technique for reducing rotor vibrations in the complex flow environment of a closely-spaced transonic stage row. Moderate increases in stage performance were also measured.

Experimental Investigation of Effects of Leading-Edge Tubercles on Compressor Cascade Performance

2014 ◽  
Author(s):  
M. C. Keerthi ◽  
Abhijit Kushari ◽  
Ashoke De ◽  
Arun Kumar
Keyword(s):  
Incidence Angle ◽  
Axial Compressor ◽  
Axial Flow ◽  
Leading Edge ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Stall Margin ◽  
Axial Compressors ◽  
Pressure Loss Coefficient ◽  
Lift And Drag

In the present study, the effectiveness of passive structures called tubercles on an axial compressor blade row is studied experimentally. Tubercles are the modifications to the leading edge of an airfoil in the form of blunt wave-like serrations. Although several studies on the effect of tubercles on isolated blades are available in literature, detailed study of their effect on a cascade of blades, such as in the case of an axial flow turbo-machine is lacking. Such an application in an axial compressor will result in a significant increase in the stall margin. Presently, experiments have been performed on a linear compressor cascade with a blade height of 0.15 m and mean chord of 0.06 m, on a NACA 65209 airfoil profile. The plain and modified blades are fabricated using rapid prototyping to ensure conformity to the required geometry. The cascade is designed in such a way that the incidence (angle of attack) and the stagger can be changed easily. The measurements are taken at the exit plane using a five-hole Pitot probe to obtain three-components of velocity and static pressure data over fine measurement grids. The effect is determined in terms of lift and drag coefficients, lift-to-drag ratio and total pressure loss coefficient. Experiments have been carried out for different pitch and amplitude (serration depth) of tubercles to understand their effect. The stall incidence angle for the best performing blade is found to increase up to 8.6° from that of the unmodified blade of 6.0°. Application of such structures in axial compressor blades may well be adequate to prevent stalling in axial compressors over a wide operating range.

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