Experimental Study of Surge Precursors in a High-Speed Multistage Compressor

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Nicolas Courtiade ◽  
Xavier Ottavy
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Rotation Speed ◽  
Characteristic Line ◽  
Pressure Measurements ◽  
High Frequency Response ◽  
Stable Operating ◽  
Variable Duration ◽  
Multistage Compressor ◽  
Operating Points

Pressure measurements using high frequency response sensors have been carried out on the third rotor of the 3.5-stage high speed compressor CREATE (rotation speed: 11,543 RPM, Rotor 1 tip speed: 313 m/s) over the complete characteristic line and during the surge transient. Precursors to the instabilities occurring near surge are observable at stable operating points. Just before surge, these precursors characterized as rotating disturbances grow in amplitude and provoke the onset a stall cell after a variable duration, which finally triggers surge. This paper presents a detailed analysis of the phenomena of rotating instabilities and surge transient and shows that it is possible to develop an antisurge active control system based on the early detection of the precursors.

Experimental Study of Surge Precursors in a High-Speed Multistage Compressor

2012 ◽  
Author(s):  
Nicolas Courtiade ◽  
Xavier Ottavy
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Rotation Speed ◽  
Critical Size ◽  
Rotating Stall ◽  
Characteristic Line ◽  
High Frequency Response ◽  
Stable Operating ◽  
Multistage Compressor ◽  
Operating Points

Pressure measurements using high frequency response sensors have been carried out on the 3rd rotor of the 3 1/2-stage high speed compressor CREATE (rotation speed: 11543 RPM, Rotor 1 tip speed: 313 m/s), over the complete characteristic line and during the surge transient. It seems that precursors to the instabilities occurring near surge are observable at stable operating points. Just before the surge, these precursors characterized as rotating disturbances transition smoothly to part span rotating stall cells, and bring the machine to surge as they grow and reach a critical size: this paper presents a detailed analysis of the phenomena of rotating stall and surge transient and shows that it is possible to develop an anti-surge active control system based on the early detection of the precursors.

Unsteady Viscous Flow in a High-Speed Core Compressor

1992 ◽  
Vol 114 (2) ◽  
pp. 287-294 ◽  
Author(s):  
M. A. Cherrett ◽  
J. D. Bryce
Keyword(s):  
High Speed ◽  
Secondary Flows ◽  
Pressure Measurements ◽  
High Frequency Response ◽  
Unsteady Viscous Flow ◽  
Novel Method ◽  
Multistage Compressor ◽  
Response Pressure ◽  
Random Fluctuations ◽  
Unsteady Pressure Measurements

A probe incorporating a miniature high-frequency response pressure transducer has been traversed behind the first three stages of a high-speed multistage compressor operating at throttle settings corresponding to near choke, peak efficiency, and near surge. A novel method of compensating for transducer temperature sensitivity was employed. Consequently, time-averaged pressures derived from the transducer were found to be in good agreement with pneumatic pressure measurements. Analysis of the unsteady pressure measurements revealed both the periodic and random fluctuations in the flow field. This provided information on rotor-rotor interaction effects and the nature of viscous blade wake and secondary flows in each stage.

scholarly journals Unsteady Viscous Flow in a High Speed Core Compressor

1991 ◽  
Author(s):  
M. A. Cherrett ◽  
J. D. Bryce
Keyword(s):  
High Speed ◽  
Secondary Flows ◽  
Pressure Measurements ◽  
High Frequency Response ◽  
Unsteady Viscous Flow ◽  
Novel Method ◽  
Multistage Compressor ◽  
Response Pressure ◽  
Random Fluctuations ◽  
Unsteady Pressure Measurements

A probe incorporating a miniature high-frequency response pressure transducer has been traversed behind the first three stages of a high-speed multistage compressor operating at throttle settings corresponding to near choke, peak efficiency and near surge. A novel method of compensating for transducer temperature sensitivity was employed. Consequently, time-averaged pressures derived from the transducer were found to be in good agreement with pneumatic pressure measurements. Analysis of the unsteady pressure measurements revealed both the periodic and random fluctuations in the flowfield. This provided information on rotor-rotor interaction effects and the nature of viscous blade wake and secondary flows in each stage.

An evaluation technique for high-frequency dynamic behavior of a sandwich microcantilever beam

2017 ◽  
Vol 21 (3) ◽  
pp. 1133-1149
Author(s):  
Yun Young Kim
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Beam Theory ◽  
Tone Burst ◽  
Ultrasonic Frequency ◽  
Vibration Modes ◽  
High Frequency Response ◽  
Frequency Regime ◽  
Contact Transducer ◽  
Microcantilever Beam

A method was developed to measure the first- and second-order vibration modes in a sandwich microcantilever beam oscillating in the megahertz frequency regime in the present study. Taking advantage of the ultrasonic frequency, a test platform was developed to induce free vibration of the microcantilever using a high-power radio frequency pulser that transmits tone burst signals to a contact transducer, and the resonant frequencies of the microcantilever were measured using a laser-optic interferometer. Results show that the microcantilever’s vibration above 8 MHz can be successfully detected, and its vibration modes were identified through a theoretical study based on the Euler–Bernoulli beam theory and a numerical analysis using the finite element method. The present study proposes a facile and effective way to actuate a high-speed sandwich microcantilever and detect its high-frequency response so that the technique can be employed to study the characteristics of micro- and nanomechanical sandwich structures and their properties.

scholarly journals Observations on Rotating Instabilities and Spike Type Stall Inception in a High-Speed Multistage Compressor

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Johannes Schreiber ◽  
Benoit Paoletti ◽  
Xavier Ottavy
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Stall Inception ◽  
Time Period ◽  
Type Flow ◽  
Different Types ◽  
Multistage Compressors ◽  
Multistage Compressor ◽  
Field Modulation ◽  
Rotating Instability

This work investigates high-frequency measurements for the contribution to the understanding of different stall inception types in high-speed multistage compressors. A 3.5-stage high-speed axial multistage compressor is investigated with a 2 MW test rig in the Laboratoire de Mécanique des Fluides et d’Acoustique (LMFA) at Ecole Centrale de Lyon, France. Two different types of instabilities arise in this compressor as a function of shaft speed. At part speed, a controversy called “rotating instability” type flow field modulation is identified with the measurements. New results are the demonstration of the periodic behavior of this instability and the analogy to classical frequency modulation, periodic to one revolution of the instability. Furthermore, the amplitude of the instability is modulated by the time period of a rotor revolution. At nominal speed, the abrupt spike type stall inception is detected, taking usually less than five rotor revolutions.

Overtip Pressure Measurements in a Cold-Flow Turbine Rig

1990 ◽  
Author(s):  
R. C. Kingcombe ◽  
I. M. Smith ◽  
R. V. Steeden
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Significant Loss ◽  
Rotor Blades ◽  
Pressure Measurements ◽  
Pressure Transducers ◽  
Cold Flow ◽  
High Frequency Response ◽  
Axial Turbines

In shroudless axial turbines the flow over the tips of the rotor blades is complex and accounts for significant loss of efficiency. In order to investigate the structure of this overtip flow, a row of high frequency response miniature pressure transducers was mounted in the casing of a cold flow turbine rig in the region swept by the rotor tips.

Analysis and modelling of unsteady shock train motions

2018 ◽  
Vol 846 ◽  
pp. 240-262 ◽  
Author(s):  
Bing Xiong ◽  
Xiao-qiang Fan ◽  
Zhen-guo Wang ◽  
Yuan Tao
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Back Pressure ◽  
Pressure Measurements ◽  
Rectangular Duct ◽  
Shock Train ◽  
Flow Parameters ◽  
Constant Area ◽  
Schlieren Techniques ◽  
Moving Speed

The characteristics and mechanism for unsteady shock train motions were experimentally studied in a constant-area rectangular duct. High-speed Schlieren techniques and high-frequency pressure measurements were utilized in this research. The results show that the shock train undergoes periodical motions in response to downstream periodical excitations. The mechanism for unsteady shock train motions is that the shock train keeps changing its moving speed to change the relative Mach number ahead of shock train to match the varying back-pressure condition. It can be found that the unsteady shock train motion can be predicted well with a theoretical model, which is based on this mechanism. A correlation between the amplitude of shock train motions and some flow parameters was illustrated using an analytical equation, which was confirmed by the experimental results.

Experimental and Numerical Investigation of the Performance Instability in a Mixed-Flow Impeller

2002 ◽  
Author(s):  
Jens Friedrichs ◽  
Gu¨nter Kosyna
Keyword(s):  
Energy Transfer ◽  
Momentum Transfer ◽  
Pressure Measurements ◽  
Velocity Measurements ◽  
Transfer Energy ◽  
Rotating System ◽  
Mixed Flow ◽  
Stable Operating ◽  
Specific Speed ◽  
Operating Points

This paper describes the recent investigations and results on performance and NPSH-instabilities of a mixed-flow impeller. Several techniques (experimental and numerical) were combined to explain the specific phenomena in the behaviour of impeller momentum-transfer (energy-transfer) under non-cavitating and cavitating conditions. Subject of the investigations was a shrouded impeller of medium specific speed (nq = 61) which shows a performance instability (hysteresis) described by two stable operating points and a NPSH3%-peak at the same particular flow rate. Blade pressure measurements in the rotating system as well as velocity measurements downstream of the impeller in combination with CFD-results were used to explain the differences in momentum-transfer leading to the unstable performance behaviour.

scholarly journals The impulsive motion of a liquid resulting from a particle collision

1998 ◽  
Vol 375 ◽  
pp. 345-361 ◽  
Author(s):  
R. ZENIT ◽  
M. L. HUNT
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Pressure Pulse ◽  
Fluid Pressure ◽  
Particle Diameter ◽  
Digital Camera ◽  
Particle Collision ◽  
High Frequency Response ◽  
Response Pressure ◽  
Impulse Pressure

When two particles collide in a liquid, the impulsive acceleration due to the rebound produces a pressure pulse that is transmitted through the fluid. Detailed measurements were made of the pressure pulse and the motion of the particles by generating controlled collisions with an immersed dual pendulum. The experiments were performed for a range of impact velocities, angles of incidence, and distances between the wall and the pairs of particles. The radiated fluid pressure was measured using a high-frequency-response pressure transducer, and the motion of the particles was recorded using a high-speed digital camera. The magnitude of the impulse pressure was found to scale with the particle velocity, the particle diameter and the density of the fluid. Additionally, a model is proposed to predict the impulse field in the fluid based on the impulse pressure theory. The model agrees well with the experimental measurements.

Influence of Rotor Tip Flow Field Mis-Prediction on Rotating Disturbance Near Surge in a High Speed Multistage Compressor

2016 ◽  
Author(s):  
Johannes Schreiber ◽  
Xavier Ottavy ◽  
Ghislaine Ngo Boum ◽  
Nicolas Gourdain
Keyword(s):  
Flow Field ◽  
High Frequency ◽  
High Speed ◽  
Periodic Oscillation ◽  
Aircraft Engine ◽  
Numerical Results ◽  
Operating Point ◽  
Stall Inception ◽  
Frequency Measurements ◽  
Multistage Compressor

In this work, unsteady numerical results and high-frequency measurements are investigated from nominal to loaded operating points with the objective to contribute to the understanding of pre-stall rotating disturbances. A 3.5 stages high speed axial multistage compressor is investigated on a 2 MW test rig in the laboratory of fluid mechanics (LMFA) at Ecole Centrale de Lyon, France. The compressor has been built by Snecma, and is representative of modern high-pressure rear blocks of a modern aircraft engine. The unsteady numerical results predict a rotating disturbance in the tip flow field of the rotor 2 at the loaded operating point. It causes a frequency which is not a multiple of the periodicity of the compressor, and is rotating at about 72% of the shaft speed. The mesh independency of this disturbance is ensured. The analysis of the circumferential and axial propagation of the disturbance reveals a rotating instability like phenomenon. Most characteristic is the very important periodic oscillation of the tip leakage vortex trajectory, leading to a modulation of the leakage flow in the neighboring tip gap. The influence of the neighboring blade rows is investigated by filtering their unsteady contribution by means of mixing planes up and/or downstream of the rotor 2. In either case, the rotating disturbance is found to be still present. There are no traces of this rotating disturbance in the high-frequency measurements investigated at a near surge operating point. A spike like stall inception and almost instantaneous surge inception is identified. The mis-prediction of the tip region flow field in the rotors 2 and 3 is believed to cause the mis-prediction of the pre-stall disturbance.

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