scholarly journals High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000047-000052 ◽  
Author(s):  
Robert S. Okojie ◽  
Roger D. Meredith ◽  
Clarence T. Chang ◽  
Ender Savrun
Keyword(s):  
Silicon Carbide ◽  
Signal To Noise Ratio ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Operating Conditions ◽  
Thermoacoustic Instabilities ◽  
Laboratory Characterization ◽  
Dynamic Pressure Measurements ◽  
Low Sensitivity ◽  
Flow Stream

Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 °C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 °C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.

A Novel Technique for Steam Turbine Exhaust Pressure Limitation Using Dynamic Pressure Sensors

2005 ◽  
Vol 219 (9) ◽  
pp. 925-932 ◽  
Author(s):  
M. S. Riaz ◽  
K. J. Barb ◽  
A Engeda
Keyword(s):  
Steam Turbine ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Operating Conditions ◽  
Strain Gauges ◽  
System Response ◽  
Main Concern ◽  
Finite Elements Analysis ◽  
Pressure Transducers ◽  
Last Stage

In this paper, a novel approach is presented to increase the operational flexibility of steam turbines. Exhaust pressure at the exit of the last-stage blades is one of the most important parameters that limit the operation of a steam turbine, especially on days with hot ambient conditions. The main concern in these off-design high-exhaust pressure operating conditions is that it can result in flow separation, which can lead to aeromechanics instabilities and thus to blade failure because of high-cycle fatigue. In the method proposed in this paper, dynamic pressure transducers are placed around the perimeter of the last-stage blade to measure the pressure variations caused by vibrating last-stage blades. This approach, which is applicable to condensing turbines only, will provide increased exhaust pressure limits through realtime monitoring of the pressure signal and thereby enable the power plant to produce more power during times of peak demand. Finite elements analysis was performed to predict the natural frequencies of the row of blades to distinguish between the synchronous and nonsynchronous modes of vibration. Strain gauges were placed on the blades to obtain the experimental frequency information of the system. Response from the dynamic pressure transducers was compared with responses from the strain gauges. An excellent agreement between the two sets of results proved the validity of the proposed method.

Correlation Analysis of Multiple Sensors for Industrial Gas Turbine Compressor Blade Health Monitoring

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Brian Kestner ◽  
Tim Lieuwen ◽  
Chris Hill ◽  
Leonard Angello ◽  
Josh Barron ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Acoustic Pressure ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Rotating Stall ◽  
Compressor Blade ◽  
Blade Vibration ◽  
Multiple Sensors ◽  
Dynamic Pressure Measurements ◽  
Industrial Gas Turbine

This paper summarizes an analysis of data obtained from an instrumented compressor of an operational, heavy duty industrial gas turbine; the goal of the aforementioned analysis is to understand some of the fundamental drivers, which may lead to compressor blade vibration. Methodologies are needed to (1) understand the fundamental drivers of compressor blade vibration, (2) quantify the severity of “events,” which accelerate the likelihood of failure and reduce the remaining life of the blade, and (3) proactively detect when these issues are occurring so that the operator can take corrective action. The motivation for this analysis lies in understanding the correlations between different sensors, which may be used to measure the fundamental drivers and blade vibrations. In this study, a variety of dynamic data was acquired from an operating engine, including acoustic pressure, bearing vibration, tip timing, and traditional gas path measurements. The acoustic pressure sensors were installed on the first four compressor stages, while the tip timing was installed on the first stage only. These data show the presence of rotating stall instabilities in the front stages of the compressor, occurring during every startup and shutdown, and manifesting itself as increased amplitude oscillations in the dynamic pressure measurements, which are manifested in blade and bearing vibrations. The data that lead to these observations were acquired during several startup and shutdown events, and clearly show that the amplitude of these instabilities and the rpm at which they occur can vary substantially.

Transient Pressure Pulsations of a Model Pump-Turbine During Power Failure

2017 ◽  
Author(s):  
Jinhong Hu ◽  
Wei Zeng ◽  
Jiandong Yang ◽  
Renbo Tang
Keyword(s):  
Rotational Speed ◽  
Guide Vane ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Open Loop ◽  
Operating Conditions ◽  
Pressure Pulsations ◽  
Transient Pressure ◽  
Pump Turbine ◽  
Power Failure

Pump-turbine can operate in either pump mode or turbine mode. The quick response to load changes as well as the ability to store energy makes it essential to the stability of power grid. When a pump-turbine works in different condition, flow-induced instabilities occur, including Rotor Stator Interaction (RSI) between the runner and vanes, vortex formations and back flow regions. To understand these complicated flow dynamics, experimental and numerical investigations have been conducted by many researchers. Among these researches, many experiments on model test rigs are mainly focused on steady state, and knowledge for instabilities during transients is still lacking. In this paper, power failure experiments with constant guide van opening are conducted on an open-loop test rig. During the process, the operating point of the pump-turbine in the 4 quadrant characteristics moves from pump region through the brake region, turbine region to turbine brake region. Finally the pump-turbine settled down at runaway rotational speed. In our experiments, flow rate, rotational speed, torque, pressure in the spiral casing and the draft tube inlet are measured. Especially, dynamic pressure sensors mounted in the guide vane channels are used to measure transient pressure pulsations. Measured data are analyzed in both time domain and frequency domain. Results indicate that during power failure pressure pulsations in the vane channels vary significantly with the operating conditions. In the pump region, pressure pulsations are mainly composed of RSI. In the brake region, intensive stochastic noises occur, and the amplitude of RSI rises. In the turbine region, the magnitude of pressure pulsations drops sharply as the noise intensity goes down. In the turbine brake region, significant noises appear, and the amplitude of RSI increases dramatically.

Correlation Analysis of Multiple Sensors for Industrial Gas Turbine Compressor Blade Health Monitoring

2014 ◽  
Author(s):  
Brian Kestner ◽  
Chris Hill ◽  
Leonard Angello ◽  
Josh Barron ◽  
Tim Lieuwen
Keyword(s):  
Gas Turbine ◽  
Acoustic Pressure ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Rotating Stall ◽  
Compressor Blade ◽  
Blade Vibration ◽  
Multiple Sensors ◽  
Dynamic Pressure Measurements ◽  
Industrial Gas Turbine

This paper summarizes an analysis of data obtained from an instrumented compressor of an operational, heavy duty industrial gas turbine; the goal of the aforementioned analysis is to understand some of the fundamental drivers which may lead to compressor blade vibration. Methodologies are needed to 1.) understand the fundamental drivers of compressor blade vibration, 2.) quantify the severity of “events” which accelerate the likelihood of failure and reduce the remaining life of the blade, and 3.) proactively detect when these issues are occurring so that the operator can take corrective action. The motivation for this analysis lies in understanding the correlations between different sensors which may be used to measure the fundamental drivers and blade vibrations. In this study, a variety of dynamic data was acquired from an operating engine, including acoustic pressure, bearing vibration, tip timing, and traditional gas path measurements. The acoustic pressure sensors were installed on the first four compressor stages, while the tip timing was installed on the first stage only. These data show the presence of rotating stall instabilities in the front stages of the compressor, occurring during every startup and shutdown, and manifesting itself as increased amplitude oscillations in the dynamic pressure measurements which are manifested in blade and bearing vibrations. The data that lead to these observations were acquired during several startup and shutdown events, and clearly show that the amplitude of these instabilities and the rpm at which they occur can vary substantially.

Dynamic Pressure Data Acquisition Via Strain Gage Measurements

2005 ◽  
Author(s):  
Gyorgy Szasz ◽  
Karen K. Fujikawa ◽  
Raju Ananth
Keyword(s):  
Strain Gage ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Dynamic Pressure ◽  
Operating Conditions ◽  
Pressure Transducers ◽  
Piping Systems ◽  
Dynamic Pressure Measurements ◽  
Main Steam

Dynamic pressure measurements are often helpful in characterizing operating conditions within industrial piping. The most straight forward method to obtain this type of data is to mount pressure transducers on the piping [6]. The orifice necessary for these instruments, frequently presents an undesirable opening in the pressure boundary of the affected system. One type of pressure transducer employs a strain gage mounted internally on a membrane that is exposed to the pressure to be measured [4, 5]. The deformation of the membrane is proportional to the pressure to be measured and is reported as a pressure value. A union of these two concepts yields the idea of mounting the gages directly on the piping and thereby eliminating the need for compromising piping integrity. One of the challenges is performing this measurement in the presence of significant axial train that is not related to the internal pressure. In the recent past Structural Integrity Associates Inc. has successfully applied this innovative technique to several main steam piping systems in various nuclear power plants in the US. This paper will describe some of the considerations regarding compensation for interfering axial strains as well as provide sample results from existing installations.

scholarly journals Reproducibility of C. I. P.-compatible dynamic pressure measurements

2020 ◽  
Vol 87 (10) ◽  
pp. 630-636
Author(s):  
Oliver Slanina ◽  
Susanne Quabis ◽  
Robert Wynands
Keyword(s):  
Dynamic Pressure ◽  
Storage Conditions ◽  
Dynamic Measurement ◽  
Gas Pressure ◽  
Pressure Measurements ◽  
Small Arms ◽  
Minimum Pressure ◽  
Maximum Value ◽  
Preliminary Study ◽  
Dynamic Pressure Measurements

AbstractTo ensure the safety of users like hunters and sports shooters, the dynamic pressure inside an ammunition cartridge must not exceed a maximum value. We have investigated the reproducibility of the dynamic measurement of the gas pressure inside civilian ammunition cartridges during firing, when following the rules formulated by the Permanent International Commission for the Proof of Small Arms (C. I. P.). We find an in-house spread of 0.8 % between maximum and minimum pressure for runs with the same barrel and of 1.8 % among a set of three barrels. This sets a baseline for the expected agreement in measurement comparisons between different laboratories. Furthermore, a difference of more than 3 % is found in a preliminary study of the influence of ammunition storage conditions.

scholarly journals Experimental Study on Dynamic Combustion Characteristics in Swirl-Stabilized Combustors

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1609
Author(s):  
Donghyun Hwang ◽  
Kyubok Ahn
Keyword(s):  
Experimental Study ◽  
Heat Release ◽  
Dynamic Pressure ◽  
Combustion Instability ◽  
Flame Structure ◽  
Pressure Sensors ◽  
Necessary Condition ◽  
Rayleigh Criterion ◽  
Pressure Oscillations ◽  
Geometric Conditions

An experimental study was performed to investigate the combustion instability characteristics of swirl-stabilized combustors. A premixed gas composed of ethylene and air was burned under various flow and geometric conditions. Experiments were conducted by changing the inlet mean velocity, equivalence ratio, swirler vane angle, and combustor length. Two dynamic pressure sensors, a hot-wire anemometer, and a photomultiplier tube were installed to detect the pressure oscillations, velocity perturbations, and heat release fluctuations in the inlet and combustion chambers, respectively. An ICCD camera was used to capture the time-averaged flame structure. The objective was to understand the relationship between combustion instability and the Rayleigh criterion/the flame structure. When combustion instability occurred, the pressure oscillations were in-phase with the heat release oscillations. Even if the Rayleigh criterion between the pressure and heat release oscillations was satisfied, stable combustion with low pressure fluctuations was possible. This was explained by analyzing the dynamic flow and combustion data. The root-mean-square value of the heat release fluctuations was observed to predict the combustion instability region better than that of the inlet velocity fluctuations. The bifurcation of the flame structure was a necessary condition for combustion instability in this combustor. The results shed new insight into combustion instability in swirl-stabilized combustors.

scholarly journals CMUT-Based Sensor for Acoustic Emission Application: Experimental and Theoretical Contributions to Sensitivity Optimization

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2042
Author(s):  
Redha Boubenia ◽  
Patrice Le Moal ◽  
Gilles Bourbon ◽  
Emmanuel Ramasso ◽  
Eric Joseph
Keyword(s):  
Signal Processing ◽  
Signal To Noise Ratio ◽  
Ultrasonic Transducer ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Signal To Noise ◽  
Coupling Conditions ◽  
Sensor Structure ◽  
Noise Ratio ◽  
Electrical Connections

The paper deals with a capacitive micromachined ultrasonic transducer (CMUT)-based sensor dedicated to the detection of acoustic emissions from damaged structures. This work aims to explore different ways to improve the signal-to-noise ratio and the sensitivity of such sensors focusing on the design and packaging of the sensor, electrical connections, signal processing, coupling conditions, design of the elementary cells and operating conditions. In the first part, the CMUT-R100 sensor prototype is presented and electromechanically characterized. It is mainly composed of a CMUT-chip manufactured using the MUMPS process, including 40 circular 100 µm radius cells and covering a frequency band from 310 kHz to 420 kHz, and work on the packaging, electrical connections and signal processing allowed the signal-to-noise ratio to be increased from 17 dB to 37 dB. In the second part, the sensitivity of the sensor is studied by considering two contributions: the acoustic-mechanical one is dependent on the coupling conditions of the layered sensor structure and the mechanical-electrical one is dependent on the conversion of the mechanical vibration to electrical charges. The acoustic-mechanical sensitivity is experimentally and numerically addressed highlighting the care to be taken in implementation of the silicon chip in the brass housing. Insertion losses of about 50% are experimentally observed on an acoustic test between unpackaged and packaged silicon chip configurations. The mechanical-electrical sensitivity is analytically described leading to a closed-form amplitude of the detected signal under dynamic excitation. Thus, the influence of geometrical parameters, material properties and operating conditions on sensitivity enhancement is clearly established: such as smaller electrostatic air gap, and larger thickness, Young’s modulus and DC bias voltage.

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