This work employs finite element (FE) software to perform a thermal modeling of a proposed absolute radiometer designed for the future satellite mission of total solar irradiance measurement. Both steady-state and transient analyses have been performed to obtain the temperature distribution and history. The cavity-type absolute radiometer employs the electrical-substitution technique and active temperature control to determine the radiant power entering the receiving cavity. The nonequivalence between the shutter-open mode and shutter-closed mode due to different temperature distributions is a major factor that affects the radiometric accuracy. The steady-state analysis shows that the nonequivalence is a function of sensor positions and can be minimized by properly choosing the electrical heating method and the temperature sensor location. The transient analysis provides the temperature response for a step power input. In order to reduce the computational time, simplified lumped-heat-capacity models have been developed by applying the least-squares fitting technique to the transient result of the FE model. The two-lumped-heat-capacity model demonstrates a better accuracy than the single-lumped-heat-capacity model and will facilitate the controller design.
{"title":"Thermal Analysis of an Absolute Radiometer Designed for the Future Satellite Mission of Total Solar Irradiance Measurement","authors":"Y. J. Shen, D. Chen, Z. M. Zhang","doi":"10.1115/imece1999-1119","DOIUrl":"https://doi.org/10.1115/imece1999-1119","url":null,"abstract":"\u0000 This work employs finite element (FE) software to perform a thermal modeling of a proposed absolute radiometer designed for the future satellite mission of total solar irradiance measurement. Both steady-state and transient analyses have been performed to obtain the temperature distribution and history. The cavity-type absolute radiometer employs the electrical-substitution technique and active temperature control to determine the radiant power entering the receiving cavity. The nonequivalence between the shutter-open mode and shutter-closed mode due to different temperature distributions is a major factor that affects the radiometric accuracy. The steady-state analysis shows that the nonequivalence is a function of sensor positions and can be minimized by properly choosing the electrical heating method and the temperature sensor location. The transient analysis provides the temperature response for a step power input. In order to reduce the computational time, simplified lumped-heat-capacity models have been developed by applying the least-squares fitting technique to the transient result of the FE model. The two-lumped-heat-capacity model demonstrates a better accuracy than the single-lumped-heat-capacity model and will facilitate the controller design.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124405220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heat flux measurement is not simple; care is required in selecting a suitable sensor for a given application. Surface substrate properties and the convective and radiative environment determine the choice of sensors. Mounting of the sensor, especially in calibration versus application, influences accuracy of measurement. The purpose of the present study is to increase awareness of potential errors in heat flux sensor use. This paper compares sensor performance in general by examining results of testing three commercially available sensors and by numerical modeling of these sensors. Comparisons of sensor calibrations in the NIST convective heat flux calibration facility are made with manufacturer calibrations and give evidence of potential pitfalls when using a sensor in a different environment than the calibration environment. Modeling results help explain observed data, demonstrating specific sensor parameters that can lead to significantly different calibrations in different environments.
{"title":"Performance and Modeling of Heat Flux Sensors in Different Environments","authors":"D. Holmberg, C. Womeldorf","doi":"10.1115/imece1999-1105","DOIUrl":"https://doi.org/10.1115/imece1999-1105","url":null,"abstract":"\u0000 Heat flux measurement is not simple; care is required in selecting a suitable sensor for a given application. Surface substrate properties and the convective and radiative environment determine the choice of sensors. Mounting of the sensor, especially in calibration versus application, influences accuracy of measurement. The purpose of the present study is to increase awareness of potential errors in heat flux sensor use. This paper compares sensor performance in general by examining results of testing three commercially available sensors and by numerical modeling of these sensors. Comparisons of sensor calibrations in the NIST convective heat flux calibration facility are made with manufacturer calibrations and give evidence of potential pitfalls when using a sensor in a different environment than the calibration environment. Modeling results help explain observed data, demonstrating specific sensor parameters that can lead to significantly different calibrations in different environments.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127787856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present work is concerned with the development of a robust three dimensional reconstruction algorithm for applications involving tomography. In an earlier study it was shown that among the ART family of algorithms the multiplicative algebraic reconstruction algorithm (MART) was the most appropriate for tomographic reconstruction. In the present work, the MART algorithm has been extended so that (a) its performance is acceptable over a wider range of relaxation factors, (b) the time requirement for convergence to a solution is lower and (c) its performance is less sensitive to noise in the projection data. Two applications have been considered for evaluating the proposed algorithms namely a circular region with holes and experimental data recorded in a differentially heated fluid layer using an interferometer. The algorithms proposed are seen to be clearly an improvement over those presently available.
{"title":"Three Dimensional Reconstruction From Limited Projection Data Using a Novel MART Algorithm","authors":"D. Mishra, K. Muralidhar, P. Munshi","doi":"10.1115/imece1999-1101","DOIUrl":"https://doi.org/10.1115/imece1999-1101","url":null,"abstract":"The present work is concerned with the development of a robust three dimensional reconstruction algorithm for applications involving tomography. In an earlier study it was shown that among the ART family of algorithms the multiplicative algebraic reconstruction algorithm (MART) was the most appropriate for tomographic reconstruction. In the present work, the MART algorithm has been extended so that (a) its performance is acceptable over a wider range of relaxation factors, (b) the time requirement for convergence to a solution is lower and (c) its performance is less sensitive to noise in the projection data. Two applications have been considered for evaluating the proposed algorithms namely a circular region with holes and experimental data recorded in a differentially heated fluid layer using an interferometer. The algorithms proposed are seen to be clearly an improvement over those presently available.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128601392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Transient heat-transfer data have recently been obtained in hypersonic wind tunnels at the Arnold Engineering Development Center (AEDC) with miniaturized fast-response Schmidt-Boelter gages. These sensors have time constants in the 10- to 15-msec range, but have response characteristics that are usually less than first-order. This presents a requirement for a general data reduction method to prevent degradation of the accuracy of the experimental data. A consistent nonambiguous data reduction methodology for fast-response Schmidt-Boelter heat-transfer gages is presented which is easy to implement in an algorithmic fashion. Timewise correction of measured Schmidt-Boelter gage heat flux is no more difficult than that involved in a classical first-order system (Gardon gage), and only involves the determination of a characteristic time measure of the integrated energy deficiency inherent in the gage response. This characteristic time measure is easily determined from the gage response characterization to a step input heat flux by numerical integration of the response versus time data.
{"title":"Data Reduction Methodology for Fast-Response Schmidt-Boelter Heat-Transfer Gages","authors":"John C. Adams, C. Kidd","doi":"10.1115/imece1999-1103","DOIUrl":"https://doi.org/10.1115/imece1999-1103","url":null,"abstract":"\u0000 Transient heat-transfer data have recently been obtained in hypersonic wind tunnels at the Arnold Engineering Development Center (AEDC) with miniaturized fast-response Schmidt-Boelter gages. These sensors have time constants in the 10- to 15-msec range, but have response characteristics that are usually less than first-order. This presents a requirement for a general data reduction method to prevent degradation of the accuracy of the experimental data. A consistent nonambiguous data reduction methodology for fast-response Schmidt-Boelter heat-transfer gages is presented which is easy to implement in an algorithmic fashion. Timewise correction of measured Schmidt-Boelter gage heat flux is no more difficult than that involved in a classical first-order system (Gardon gage), and only involves the determination of a characteristic time measure of the integrated energy deficiency inherent in the gage response. This characteristic time measure is easily determined from the gage response characterization to a step input heat flux by numerical integration of the response versus time data.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131882541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Loop heat pipes currently are being used in the thermal control systems for satellites. To expand possible loop heat pipe applications, information regarding response to transient heat inputs is required. In this investigation, two loop heat pipes with dual compensation chambers were subjected to heat inputs of varying magnitude, frequency, and waveform (square and sinusoidal). The performance of each loop heat pipe under these conditions was evaluated in different gravitational orientations. The upper and lower limits of heat transport also were assessed. A principle finding was that cyclic heat loads tended to aid startup of the loop heat pipes at the low power inputs.
{"title":"Response of Loop Heat Pipes to Transient Heat Loads","authors":"J. Long, J. Ochterbeck","doi":"10.1115/imece1999-1139","DOIUrl":"https://doi.org/10.1115/imece1999-1139","url":null,"abstract":"\u0000 Loop heat pipes currently are being used in the thermal control systems for satellites. To expand possible loop heat pipe applications, information regarding response to transient heat inputs is required. In this investigation, two loop heat pipes with dual compensation chambers were subjected to heat inputs of varying magnitude, frequency, and waveform (square and sinusoidal). The performance of each loop heat pipe under these conditions was evaluated in different gravitational orientations. The upper and lower limits of heat transport also were assessed. A principle finding was that cyclic heat loads tended to aid startup of the loop heat pipes at the low power inputs.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117174970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pursuant to implementation of a new mechanical engineering curriculum at Clemson University, results of the new introductory course in thermal-fluid science are presented. This course is situated in the second semester of the sophomore year for mechanical engineering majors, and is a prerequisite for the subsequent courses in thermodynamics and fluid mechanics. In addition to introducing thermodynamic property analysis, the course develops conservation laws for mass, momentum, and energy and provides an emphasis in design. Discussion is presented of the motivation, placement in the overall curriculum, interaction with other curriculum elements, and the selection of textbooks.
{"title":"Results of Implementing an Introductory Course: Foundations of Thermal-Fluid Sciences","authors":"J. Ochterbeck, J. Gaddis","doi":"10.1115/imece1999-1137","DOIUrl":"https://doi.org/10.1115/imece1999-1137","url":null,"abstract":"\u0000 Pursuant to implementation of a new mechanical engineering curriculum at Clemson University, results of the new introductory course in thermal-fluid science are presented. This course is situated in the second semester of the sophomore year for mechanical engineering majors, and is a prerequisite for the subsequent courses in thermodynamics and fluid mechanics. In addition to introducing thermodynamic property analysis, the course develops conservation laws for mass, momentum, and energy and provides an emphasis in design. Discussion is presented of the motivation, placement in the overall curriculum, interaction with other curriculum elements, and the selection of textbooks.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122063281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The use of passive safety system in AC600, the Chinese advanced 600 MWe PWR proposed by NPIC, together with other improvements, such as simplification and advanced I&C etc., makes the plant more safe, economic and reliable. The core damage frequency (CDF) decreases from less than 10−4 of conventional PWR to less than 10−5 to 10−6 and the plant available factor increases to ∼90%. The passive safety system of AC600 consists of three complete independent systems. They are passive containment cooling system (passive CC system), passive core residual heat removal system (passive CRHR system) and passive safety injection system (CMT). To verify and demonstrate the AC600’s innovative passive safety features and to obtain an experimental database for system design modification and optimizing, and for computer code development and assessment, the experimental studies on these systems were finished in NPIC during the eighth national Five Year period under the national support. In this paper, the experimental research activities on passive containment cooling system, passive CRHR system and CMT injection system, including test rigs and main results are summarized. These experiments proved the design of all these passive systems are feasible and reliable and can meet basically the required safety functions. Some undesired thermal hydraulic phenomena, for example, “water hammer”, which may have bad impacts on its safety functions and to which high attention should be given, was found and identified in these studies. All data obtained have already been used in the design improvement and next R&D program planning.
{"title":"Survey of Research Activities for Passive Safety System of AC600","authors":"Bingde Chen, Zhumao Yang, Fuyun Ji","doi":"10.1115/imece1999-1127","DOIUrl":"https://doi.org/10.1115/imece1999-1127","url":null,"abstract":"\u0000 The use of passive safety system in AC600, the Chinese advanced 600 MWe PWR proposed by NPIC, together with other improvements, such as simplification and advanced I&C etc., makes the plant more safe, economic and reliable. The core damage frequency (CDF) decreases from less than 10−4 of conventional PWR to less than 10−5 to 10−6 and the plant available factor increases to ∼90%.\u0000 The passive safety system of AC600 consists of three complete independent systems. They are passive containment cooling system (passive CC system), passive core residual heat removal system (passive CRHR system) and passive safety injection system (CMT). To verify and demonstrate the AC600’s innovative passive safety features and to obtain an experimental database for system design modification and optimizing, and for computer code development and assessment, the experimental studies on these systems were finished in NPIC during the eighth national Five Year period under the national support.\u0000 In this paper, the experimental research activities on passive containment cooling system, passive CRHR system and CMT injection system, including test rigs and main results are summarized. These experiments proved the design of all these passive systems are feasible and reliable and can meet basically the required safety functions. Some undesired thermal hydraulic phenomena, for example, “water hammer”, which may have bad impacts on its safety functions and to which high attention should be given, was found and identified in these studies. All data obtained have already been used in the design improvement and next R&D program planning.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133498005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To investigate the thermal and velocity fields in the liquid phase of turbulent subcooled boiling flow, local measurements were made in the bubbly regime. The boiling flow, of Refrigerant-113, was created in a vertical annular channel whose inner wall was heated. The technique involves the simultaneous use of a two-component laser Doppler Velocimeter (LDV) for measuring the velocity field, and a fast-response cold-wire for measuring the temperature field. The LDV measuring volume (m.v.) dimensions in the liquid were: 290 microns spanwise length × 55 microns diameter. The 3.8 micron diameter tungsten cold-wire had an active length of 300 microns and was placed 250 microns downstream of the center of the LDV m.v. The cold-wire in conjunction with an active phase-lead compensation circuit had a temperature response time constant of 0.3±0.02 ms in the liquid flow. To validate the measurement technique, the velocity and thermal fields were first measured in heated single-phase liquid flow in the same channel and compared with the corresponding computed fields. Selected results are presented. Next, measurements in boiling flow at one experimental condition are presented and their intended use in multidimensional two-fluid modeling of the flow is briefly discussed.
{"title":"Measurement of the Thermal and Velocity Fields in the Liquid Phase of Turbulent Subcooled Bubbly Boiling Flow","authors":"R. Roy, S. Kang, J. A. Zarate","doi":"10.1115/imece1999-1133","DOIUrl":"https://doi.org/10.1115/imece1999-1133","url":null,"abstract":"\u0000 To investigate the thermal and velocity fields in the liquid phase of turbulent subcooled boiling flow, local measurements were made in the bubbly regime. The boiling flow, of Refrigerant-113, was created in a vertical annular channel whose inner wall was heated. The technique involves the simultaneous use of a two-component laser Doppler Velocimeter (LDV) for measuring the velocity field, and a fast-response cold-wire for measuring the temperature field. The LDV measuring volume (m.v.) dimensions in the liquid were: 290 microns spanwise length × 55 microns diameter. The 3.8 micron diameter tungsten cold-wire had an active length of 300 microns and was placed 250 microns downstream of the center of the LDV m.v. The cold-wire in conjunction with an active phase-lead compensation circuit had a temperature response time constant of 0.3±0.02 ms in the liquid flow.\u0000 To validate the measurement technique, the velocity and thermal fields were first measured in heated single-phase liquid flow in the same channel and compared with the corresponding computed fields. Selected results are presented. Next, measurements in boiling flow at one experimental condition are presented and their intended use in multidimensional two-fluid modeling of the flow is briefly discussed.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"216 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124249570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An analytical and numerical investigation has been carried out to ascertain the possibility of using a pulsed periodic surface heat flux to measure local surface heat transfer coefficients. The proposed technique is an extension of a previously proven experimental method. It is based upon the premise that the harmonics of a surface temperature response to an imposed periodic pulse will display phase shifting behavior that is a function of the thermophysical properties of the surface, the local heat transfer coefficient and the harmonic frequency. The phase behavior is not a function of the magnitude of the energy deposited by the pulse. Since phase behavior is being investigated there is no requirement to calibrate the surface temperature-sensing device. The numerical solution confirms the analytical results, which were obtained using a non-rigorous mathematical assumption. Results indicate that in order to maximize the sensitivity of the proposed experimental technique the pulse frequency should be kept low, the surface layer thin and the substrate thermal conductivity and diffusivity as low as possible.
{"title":"Proposed Experimental Technique for Measuring Heat Transfer Coefficients Using a Pulsed Periodic Surface Heat Flux","authors":"W. Turnbull, W. Carscallen","doi":"10.1115/imece1999-1108","DOIUrl":"https://doi.org/10.1115/imece1999-1108","url":null,"abstract":"\u0000 An analytical and numerical investigation has been carried out to ascertain the possibility of using a pulsed periodic surface heat flux to measure local surface heat transfer coefficients. The proposed technique is an extension of a previously proven experimental method. It is based upon the premise that the harmonics of a surface temperature response to an imposed periodic pulse will display phase shifting behavior that is a function of the thermophysical properties of the surface, the local heat transfer coefficient and the harmonic frequency. The phase behavior is not a function of the magnitude of the energy deposited by the pulse. Since phase behavior is being investigated there is no requirement to calibrate the surface temperature-sensing device. The numerical solution confirms the analytical results, which were obtained using a non-rigorous mathematical assumption. Results indicate that in order to maximize the sensitivity of the proposed experimental technique the pulse frequency should be kept low, the surface layer thin and the substrate thermal conductivity and diffusivity as low as possible.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"198 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132651313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes the first phase of a two-part project designed to develop a new anemometry method for use in high temperature liquid metal flows. The device will incorporate a dual-cantilever, PZT-driven touch sensor housed within a sealed, temperature resistant ceramic Pitot tube. Due to differing cantilever lengths, the device’s unloaded spectral response exhibits two distinct peaks, each corresponding to the cantilevers’ resonant frequencies. The principal of operation is based on the fact that pressure-induced forces on each cantilever produce resonant frequency shifts which can then be correlated with applied pressures. The first project phase has focused on development and testing of the dual cantilever touch-sensor and its supporting electronics. Two new concepts have been introduced in designing the touch sensor — use of a dual cantilever for simultaneous force measurement, and simultaneous detection of associated pressure-induced resonant frequency shifts. Here, we describe design of the Pitot tube, design and fabrication of the dual-cantilever sensor and electronics, and system modeling of the sensor. We also outline two pressure measurement schemes; in the first, pressure is correlated with resonant frequency shifts at constant phase while in the second, pressure is related to phase shifts (between forcing and response signals) at constant frequency. Device driving and sensing electronics have been fabricated as has the dual-cantilever touch sensor; preliminary experimental measurements of single and dual forces are presented.
{"title":"Resonance Based Force Measurement: Prelude to High-Resolution Anemometry for Liquid Metal Flows","authors":"S. Phan, R. Keanini, S. Smith, R. Hocken","doi":"10.1115/imece1999-1098","DOIUrl":"https://doi.org/10.1115/imece1999-1098","url":null,"abstract":"\u0000 This paper describes the first phase of a two-part project designed to develop a new anemometry method for use in high temperature liquid metal flows. The device will incorporate a dual-cantilever, PZT-driven touch sensor housed within a sealed, temperature resistant ceramic Pitot tube. Due to differing cantilever lengths, the device’s unloaded spectral response exhibits two distinct peaks, each corresponding to the cantilevers’ resonant frequencies. The principal of operation is based on the fact that pressure-induced forces on each cantilever produce resonant frequency shifts which can then be correlated with applied pressures. The first project phase has focused on development and testing of the dual cantilever touch-sensor and its supporting electronics. Two new concepts have been introduced in designing the touch sensor — use of a dual cantilever for simultaneous force measurement, and simultaneous detection of associated pressure-induced resonant frequency shifts. Here, we describe design of the Pitot tube, design and fabrication of the dual-cantilever sensor and electronics, and system modeling of the sensor. We also outline two pressure measurement schemes; in the first, pressure is correlated with resonant frequency shifts at constant phase while in the second, pressure is related to phase shifts (between forcing and response signals) at constant frequency. Device driving and sensing electronics have been fabricated as has the dual-cantilever touch sensor; preliminary experimental measurements of single and dual forces are presented.","PeriodicalId":120929,"journal":{"name":"Heat Transfer: Volume 4","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124371370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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