scholarly journals Study of the heat flux fluctuations intensity during flow around a circular cylinder

2021 ◽  
Vol 2039 (1) ◽  
pp. 012022
Author(s):  
V Yu Mityakov ◽  
V V Seroshtanov ◽  
V V Suchok ◽  
N A Zhidkov ◽  
A S Vlasov

Abstract An experimental study performed in an air channel using gradient heatmetry is presented, for a configuration of three heated circular cylinders with different distance between them. Cylinders were installed one by one. The main objective is to analyze the heat flux fluctuations, employing gradient heat flux sensor. The behavior of the flow in the wake behind the first cylinder under various regimes, for the specified configuration, changes the fluctuations level at the surface of the second and third cylinders. By visualizing the flow using PIV, it was possible to see areas of stagnation, separation points and other features of flow around the model. The results showed that the fluctuations level for the second cylinder is an order of magnitude lower than for the first. We can say that the first cylinder stabilizes the flow. However, at the third cylinder, this level is comparable and even higher than on the first. Use of gradient heatmetry thus made it possible for the first time to estimate the fluctuating nature of the flow and heat transfer around cylinders.

2015 ◽  
Vol 135 (8) ◽  
pp. 343-348
Author(s):  
Shinya Nakagawa ◽  
Masao Shimizu ◽  
Tsuyoshi Hamaguchi

Author(s):  
Arash Saidi ◽  
Jungho Kim

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.


2018 ◽  
Vol 69 (03) ◽  
pp. 183-189
Author(s):  
MAZARI FUNDA BUYUK ◽  
MAZARI ADNAN ◽  
HAVELKA ANTONIN ◽  
GLOMBIKOVA VIERA

The comfort performance of car seat is important factor while producing car seats, each layer of the car seat is tested separately on classical testing machines, which lacks the real car seat performance when all layers are sandwiched. The complication of car seat design and the testing method bring a great demand of portable device which can measure the comfort performance of the real car seat. In this research a novel portable device is designed which work with special heat flux sensor and the device is connected to computer by USB port and values of heat flux temperature of the water and temperature of the surface is provided by the software. Heat flux sensors measure the heat transfer through a surface, and are expressed in kw/m2. The software controls the heating plate adjustment using PID controller. The device is tested with real car seat and shows repeatable and reproducible results.


Author(s):  
Sujay Raphael-Mabel ◽  
Scott Huxtable ◽  
Andrew Gifford ◽  
Thomas E. Diller

A new type of heat flux sensor (HTHFS) has been designed and constructed for applications at high temperature and high heat flux. It is constructed by connecting solid metal plates to form brass/steel thermocouple junctions in a series circuit. The thermal resistance layer of the HTHFS consists of the thermocouple materials themselves, thus improving temperature limits and lowering the temperature disruption of the sensor. The sensor can even withstand considerable erosion of the surface with little effect on the operation. A new type of convection calibration apparatus was designed and built specifically to supply a large convection heat flux. The heat flux was supplied simultaneously to both a test and standard gage by using two heated jets of air that impinged perpendicularly on the surface of each gage. The sensitivity for the HTHFS was measured to have an average value of 20 μV/(W/cm2). The uncertainty in this result was determined to be ±10% over the entire range tested. The sensitivity agrees with the theoretically calculated sensitivity for the materials and geometry used. Recommendations for future improvements in the construction and use of the sensors are discussed.


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