scholarly journals Quantification of Heat Flux From a Reacting Thermite Spray

2009 ◽  
Author(s):  
Eric Nixon ◽  
Michelle Pantoya ◽  
Daniel Prentice
Keyword(s):  
Heat Flux ◽  
Response Time ◽  
Energetic Materials ◽  
Energetic Material ◽  
Heat Flux Sensor ◽  
Diagnostic Tools ◽  
Test Duration ◽  
Inverse Heat Conduction ◽  
Flux Measurements ◽  
Combustion Behaviors

Characterizing the combustion behaviors of energetic materials requires diagnostic tools that are often not readily or commercially available. For example, a jet of thermite spray provides a high temperature and pressure reaction that can also be highly corrosive and promote undesirable conditions for the survivability of any sensor. Developing a diagnostic to quantify heat flux from a thermite spray is the objective of this study. Quick response sensors such as thin film heat flux sensors can not survive the harsh conditions of the spray, but more rugged sensors lack the response time for the resolution desired. A sensor that will allow for adequate response time while surviving the entire test duration was constructed. The sensor outputs interior temperatures of the probes at known locations and utilizes an inverse heat conduction code to calculate heat flux values. The details of this device are discussed and illustrated. Temperature and heat flux measurements of various thermite spray conditions are reported. Results indicate that this newly developed energetic material heat flux sensor provides quantitative data with good repeatability.

Heat Flux Sensor With Minimal Impact on Boundary Conditions

2003 ◽  
Author(s):  
Arash Saidi ◽  
Jungho Kim
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Heat Flux Sensor ◽  
Inverse Heat Conduction ◽  
Minimal Impact ◽  
Sensor Performance ◽  
Flow Through ◽  
Flux Sensor ◽  
The Ideal

A technique for determining the heat transfer on the far surface of a wall based on measuring the heat transfer and temperature on the near wall is presented. Although heat transfer measurements have previously been used to augment temperature measurements in inverse heat conduction methods, the sensors used alter the heat flow through the surface, disturbing the very quantity that is desired to be measured. The ideal sensor would not alter the boundary condition that would exist were the sensor not present. The innovation of this technique in that it has minimal impact on the wall boundary condition. Since the sensor is placed on the surface of the wall, no alteration of the wall is needed. The theoretical basis for the experimental technique as well as experimental results showing the heat flux sensor performance is presented.

A Hybrid Method for Measuring Heat Flux

2009 ◽  
Vol 132 (3) ◽  
Author(s):  
David O. Hubble ◽  
Tom E. Diller
Keyword(s):  
Heat Flux ◽  
Hybrid Method ◽  
Sensor Response ◽  
Time Response ◽  
Heat Flux Sensor ◽  
Response Accuracy ◽  
Temporal Response ◽  
Heat Flux Sensors ◽  
Flux Measurements ◽  
Flux Sensor

The development and evaluation of a novel hybrid method for obtaining heat flux measurements is presented. By combining the spatial and temporal temperature measurements of a heat flux sensor, the time response, accuracy, and versatility of the sensor is improved. Sensors utilizing the hybrid method are able to make heat flux measurements on both high and low conductivity materials. It is shown that changing the thermal conductivity of the backing material four orders of magnitude causes only an 11% change in sensor response. The hybrid method also increases the time response of heat flux sensors. The temporal response is shown to increase by up to a factor of 28 compared with a standard spatial sensor. The hybrid method is tested both numerically and experimentally on both high and low conductivity materials and demonstrates significant improvement compared with operating the sensor as a spatial or temporal sensor alone.

Heat flux measurements at Teide Volcano, Tenerife, Canary Islands, by means of thermal imaging

2020 ◽  
Author(s):  
Ana Carolina Montañez Hernández ◽  
Enrica Marotta ◽  
Germán D. Padilla ◽  
Rosario Peluso ◽  
Pedro A. Hernández ◽  
...  
Keyword(s):  
Heat Flux ◽  
Specific Area ◽  
Thermal Anomaly ◽  
Heat Flux Sensor ◽  
Infrared Images ◽  
Thermal Camera ◽  
Monthly Basis ◽  
Thermal Images ◽  
Flux Measurements ◽  
The One

<p>Nowadays, scientific surveys to evaluate the thermal energy release from volcanoes are very tedious and involve performing numerous measure points to determine the heat flux of a specific area. This study tests a new method to calculate the heat flux from Teide inner crater using thermal images without the need for on-site heat flow campaigns. So far, panoramic infrared images of the study area and infrared images of thermal anomaly zones at a distance of 1 meter have been carried out in a monthly basis with a FLIR T660 thermal camera. Soil temperature of study area was also measured with a K-type thermocouple in order to compare the results between the temperature measured with the thermocouple and the one obtained by the thermal camera. The method developed in Marotta et al. 2019 to determine the heat flux from thermal images will be adapted to the peculiarities of the Teide stratovolcano, such as the topography of the inner crater. To check the reliability of the method, values obtained with a heat flux sensor, by means of the temperature gradient and those resulting from the application of the developed method are compared. Finally, the error associated to the use of thermography at a greater distance to calculate heat flux is analysed by comparing the results obtained when applying the method with thermographic images taken at 1 meter with the results obtained when applying it with the panoramic thermal images of the crater, taken at approximately 50 metres.</p>

Measurement of Heat Flux From Fires

Volume 4 ◽  
2004 ◽  
Author(s):  
Cecilia S. Lam ◽  
Alexander L. Brown ◽  
Elizabeth J. Weckman ◽  
Walter Gill
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Unit Area ◽  
Inverse Heat Conduction ◽  
Thermal Impact ◽  
Temperature Changes ◽  
One Dimensional ◽  
Conduction Heat Transfer ◽  
Flux Measurements

Heat flux is an important parameter for characterization of the thermal impact of a fire on its surroundings. However, heat flux cannot be measured directly because it represents the rate of heat transfer to a unit area of surface. Therefore, most heat flux measurements are based on the measurement of temperature changes at or near the surface of interest [1,2]. Some instruments, such as the Gardon gauge [3] and the thermopile [2], measure the temperature difference between a surface and a heat sink. In radiation-dominated environments, this difference in temperature is often assumed to be linearly related to the incident heat flux. Other sensors measure a surface and/or interior temperature and inverse heat conduction methods frequently must be employed to calculate the corresponding heat flux [1,4]. Typical assumptions include one-dimensional conduction heat transfer and negligible heat loss from the surface. The thermal properties of the gauge materials must be known and, since these properties are functions of temperature, the problem often becomes non-linear.

Time-Resolved Heat Transfer Measurements on the Tip Wall of a Ribbed Channel Using a Novel Heat Flux Sensor: Part I — Sensor and Benchmarks

2006 ◽  
Author(s):  
Tim Roediger ◽  
Helmut Knauss ◽  
Uwe Gaisbauer ◽  
Ewald Kraemer ◽  
Sean Jenkins ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbine Blades ◽  
Temperature Fields ◽  
Heat Flux Sensor ◽  
Internal Cooling ◽  
Time Resolved ◽  
Flux Measurements ◽  
Working Principle ◽  
Flux Sensor

A novel heat flux sensor was tested which allows for time-resolved heat flux measurements in internal ribbed channels related to the study of passages in gas turbine blades. The working principle of the Atomic Layer Thermopile (ALTP) sensor is based on a thermoelectric field created by a temperature gradient over an YBCO crystal (the transverse Seebeck effect). The sensors very fast frequency response allows for highly time-resolved heat flux measurements up to the 1 MHz range. This paper explains the design and working principle of the sensor, as well as the benchmarking of the sensor for several flow conditions. For internal cooling passages, this novel sensor allows for highly accurate, time-resolved measurements of heat transfer coefficients, leading to a greater understanding of the influence of fluctuations in temperature fields.

Time-Resolved Heat Transfer Measurements on the Tip Wall of a Ribbed Channel Using a Novel Heat Flux Sensor—Part I: Sensor and Benchmarks

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Tim Roediger ◽  
Helmut Knauss ◽  
Uwe Gaisbauer ◽  
Ewald Kraemer ◽  
Sean Jenkins ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbine Blades ◽  
Temperature Fields ◽  
Heat Flux Sensor ◽  
Internal Cooling ◽  
Time Resolved ◽  
Flux Measurements ◽  
Working Principle ◽  
Flux Sensor

A novel heat flux sensor was tested that allows for time-resolved heat flux measurements in internal ribbed channels related to the study of passages in gas turbine blades. The working principle of the atomic layer thermopile (ALTP) sensor is based on a thermoelectric field created by a temperature gradient over an yttrium-barium-copper-oxide (YBCO) crystal (the transverse Seebeck effect). The sensors very fast frequency response allows for highly time-resolved heat flux measurements up to the 1MHz range. This paper explains the design and working principle of the sensor, as well as the benchmarking of the sensor for several flow conditions. For internal cooling passages, this novel sensor allows for highly accurate, time-resolved measurements of heat transfer coefficients, leading to a greater understanding of the influence of fluctuations in temperature fields.

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