Development of a Single Sensor Fast Response Probe for the Measurement of Unsteady Flow behind an Axial Flow Rotor
TL;DR: In this article, a fast-response total pressure probe and the necessary calibration procedure for the measurement of unsteady flow field at the exit of the rotating blades is presented. But, this method is more competitive over established methods that use multiple sensors.
Abstract: To evaluate the accurate performance and characteristics of turbomachinery, it is important to measure the unsteady flow phenomena downstream of the rotating blades. This paper presents the development of a fast-response total pressure probe and the necessary calibration procedure for the measurement of unsteady flow field at the exit of blades. The fast-response total pressure probe is fabricated by installing a sensor in the cylindrical head of the probe. In terms of simplicity of the measurement system and data reduction method, this method is more competitive over established methods that use multiple sensors. A novel scheme of using fast response probe and virtual instrumentation technology has been successfully implemented in the current programme in place of conventional measurement methods like five-hole probe, three-hole probe and hot wire anemometer. The experiment is conducted in an axial flow compressor using virtual instrumentation technology with components like signal conditioning system, A...
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TL;DR: In this paper, a commercial oxygen sensor element and its excitation/detection unit were integrated into a newly developed probe to carry out local tracer gas concentration measurements exploiting the fluorescence behaviour.
Abstract:
Modern gas turbines present important temperature distortions in the core-engine flowpath, mainly in the form of hot and cold streaks imputed to combustor burners and components cooling systems. As they highly influence turbines performance and lifetime, the precise knowledge of the thermal field evolution through the combustor and the high-pressure turbine is fundamental. The majority of past studies investigated streaks migrations directly examining the thermal field, while a limited amount of experimental work employed approaches based on the detection of tracer gases. The latter approach provides a more detailed evaluation of the evolution and mixing of the different flows. However, the slow time response due to the employment of sampling probes and gas analysers make the investigation of a whole measurement plane extremely time consuming. To tackle this issue, in this study a commercial oxygen sensor element and its excitation/detection unit were integrated into a newly developed probe to carry out local tracer gas concentration measurements exploiting the fluorescence behaviour. The probe was provided with a Kiel-like shield, a pressure port and a thermocouple, in order to correct the readings in case of 3D flows with pressure, temperature and velocity gradients. The paper summarizes the probe development and calibration activities, with the characterization of its accuracy for different flow conditions. Finally, two probe applications are described: firstly the probe was used to detect tracer gas concentrations on a jet flow; afterwards it was traversed on the interface plane between a non-reactive, lean combustor simulator and the NGV cascade. The probe has proven to provide accurate and reliable measurements both from a quantitative and qualitative point of view even in highly 3D flow fields typical of gas turbines conditions.
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TL;DR: Fast-response aerodynamic probes are a promising alternative to other time-resolving measurement techniques such as hot-wire anemometry or laser anemometers as mentioned in this paper, which is a key to further improvements in turbomachinery.
Abstract: A better understanding of unsteady flow phenomena encountered in rotor-stator interactions is a key to further improvements in turbomachinery. Besides CFD methods yielding 3D flow field predictions, time-resolving measurement techniques are necessary to determine the instantaneous flow quantities of interest. Fast-response aerodynamic probes are a promising alternative to other time-resolving measurement techniques such as hot-wire anemometry or laser anemometry. This contribution gives an overview of the fast-response probe measurement technique, with the emphasis on the total system and its components, the development methods, the operation of such systems and the data processing requirements. A thorough optimization of all system components (such as sensor selection and packaging, probe tip construction, probe aerodynamics and data analysis) is the key of successful development. After description of the technique, examples of applications are given to illustrate its potential. Some remarks will refer to recent experiences gained by the development and application of the ETH FRAPreg system.
98 citations
"Development of a Single Sensor Fast..." refers background in this paper
...Kupferschmied et al. (2000b) and Roduner et al. (2000) suggested that a single-sensor probe could be operated in pseudo three sensor mode....
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...In selecting the sensor chip of the probe, all the basic criteria viz sensor geometry, size, pressure sensitivity, signal sensitivity and the maximum limit of pressure measured are considered (Kupferschmied et al., 2000b)....
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...As the fast response probe can be used for all types of readings, eg time dependent, time independent or both, its shape plays a very important role in reading (Kupferschmied et al., 2000b)....
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...A review of the fast response probe development was given by Sieverding et al. (2000), Ainsworth et al. (2000) and Kupferschmied et al. (2000a)....
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...Kupferschmied et al. (2000b) described two different modes of operation of a single-hole probe for the determination of the 2-dimensional velocity field together with the pressure field....
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TL;DR: In this paper, the progress in fast response measurement techniques for high speed turbomachines and application with emphasis on fast response pressure and temperature probes and blade surface sensors including pressure, heat transfer and shear stress determination.
Abstract: The growing interest for unsteady flows in turbomachines over the last two decades has led to an intensive development of fast response measurement techniques, capable of resolving with high frequency phenomena related to inlet distortion, rotating stall and blade row interference effects with blade passing frequencies ranging from 3 to 30 kHz. This development was favoured by major advances in sensor technology and data acquisition systems. The paper reviews the progress in fast response measurement techniques for high speed turbomachinery and application with emphasis on fast response pressure and temperature probes and blade surface sensors including pressure, heat transfer and shear stress determination.
87 citations
Additional excerpts
...A review of the fast response probe development was given by Sieverding et al. (2000), Ainsworth et al. (2000) and Kupferschmied et al. (2000a)....
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TL;DR: The silicon piezoresistive sensor has been extensively used in the context of gas turbine applications and some of the special issues which arise and must be addressed for accurate measurements are discussed in this article.
Abstract: Pressure measurement and turbomachinery have been intimately linked since flow field diagnosis was employed in verifying the operation of the first gas turbines. In the early years, time-mean pressures were required and extensive use of pneumatic connections between the measurement points and pressure transducers was made. Over the last two decades or so there has been a requirement to measure time-varying pressures in turbomachinery applications to bandwidths of order 100 kHz and the silicon piezoresistive pressure sensor has been the device which has been at the heart of many of the measurements. Although we mention other new developments in technology that are under way, this paper concentrates on the silicon piezoresistive sensor. The operation of the device in the context of gas turbine applications is outlined and some of the special issues which arise and must be addressed for accurate measurements are discussed. Following this, two example fields of the application of piezoresistive sensors are discussed in some detail, namely, rotating blade static pressure measurements and fast response aerodynamic probes. In both these cases instrumentation design considerations are discussed, technological implementation details given and sample data displayed and briefly discussed. Contemporary work elsewhere is included in the discussion. Finally, conclusions are drawn and the future context for the piezoresistive device is outlined.
81 citations
Additional excerpts
...A review of the fast response probe development was given by Sieverding et al. (2000), Ainsworth et al. (2000) and Kupferschmied et al. (2000a)....
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TL;DR: In this article, a system for fast-response probe measurements in turbomachine flows has been developed and tested with various in-house built probes accommodating up to four piezoresistive pressure transducers.
Abstract: A system for fast-response probe measurements in turbomachine flows has been developed and tested. The system has been designed for 40 kHz bandwidth and used with various in-house built probes accommodating up to four piezoresistive pressure transducers. The present generation of probes works accurately up to several bar pressure and 120°C temperature. The probes were found to be quite robust. The use of a miniature pressure transducer placed in the head of a probe showed that a precise packaging technique and a careful compensation of errors can considerably improve the accuracy of the pressure measurement. Methods for aerodynamic probe calibration and off-line data evaluation are briefly presented. These aimed, e.g., in the case of a four-hole probe, at measuring the velocity fluctuations as characterized by yaw, pitch, total pressure, and static pressure and at deriving mean values and spectral or turbulence parameters. Applications of the measuring system to turbomachinery flow in a radial compressor and to a turbulent pipe flow demonstrate the performance of the measuring system.
36 citations
TL;DR: In this article, a miniature fast response entropy probe and its application in the turbomachinery facilities at ETH Zurich is described. But the application of the probe is limited to the measurement of the unsteady entropy field and associated losses.
Abstract: This paper describes a recently developed miniature fast response entropy probe and its application in the turbomachinery facilities at ETH Zurich. The development of the probe is motivated by the need to more clearly document the loss generation mechanisms in the harsh environment of turbomachines. The probe is comprised of a piezoresistive sensor and a pair of thin-film gauges that measure the unsteady pressure and temperature, respectively. The unsteady relative entropy can thus be determined. The design, manufacture and calibration of the probe are first presented in detail. Its application to detail the unsteady entropy field, and associated losses, in a centrifugal compressor, axial turbine and film cooling flows are then described.
32 citations
"Development of a Single Sensor Fast..." refers background in this paper
...Mansour et al. (2008) developed miniature fast response entropy probe and its application in the turbomachinery facilities at ETH Zurich....
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