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Coefficient of kinetic friction and static friction
Typology: Schemes and Mind Maps
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Name CMS ID Section Muhammad Huzaifa 404564 ME-14-A
Wind tunnels are machines where an object is held stationary inside a tube, and air is blown around it to study the interaction between the object and the moving air. They are used to test the aerodynamic effects of aircraft, rockets, cars, and buildings. One of the important technologies to improve the Reynolds number is to reduce the temperature of the air flow inside the wind tunnel. The air flow working temperature can reach 77K at least. At this time, it is necessary to carry out thermal protection for the internal equipment of the wind tunnel. In view of the complex layout and various characteristics of the equipment in the wind tunnel, this paper takes the thermal protection and temperature control strategy of the equipment in the wind tunnel as the research object, and designs the temperature control strategy of the typical equipment from the perspectives of heating element selection, temperature control logic, temperature control algorithm and heating mode.
Journal of Physics: Conference Series, Volume 1678, 2020 3rd^ International Conference on Mechatronics and Computer Technology Engineering 18-20 September 2020, Changsha, China
Liu ZeYuan. Luo Qiang Ge ZheYang. Wang Jing. Gao QingHua
Temperature is one of the main variables need to be regulated in cryogenic wind tunnel to realize the true flight Reynolds number. Temperature control is an important index to evaluate the performance of wind tunnel. To make sensitive measurements, temperature control is very important for both the air flow and the instrumentation. This is why tunnels of this nature have very powerful temperature control systems. When the low-temperature wind tunnel is running, the air flow temperature in it can reach 77K at least, which is far lower than the normal working temperature of some kinds of mechanical, electrical and electronic equipment. Therefore, it is necessary to carry out thermal protection for its internal equipment to ensure that it is in the normal working temperature range.
The temperature control system was designed based on the PLC system, which includes the PLC control system, the distributed I/O system, power supply, and the temperature measurement and heating elements at the specific protected equipment unit. The design principle of the equipment temperature control system in the wind tunnel is shown in Figure:
PLC has strong function, high performance and low cost, can achieve very complex control function PLC has been recognized as one of the majority of users the most reliable industrial control equipment. The comparative analysis of temperature control logic mainly takes the uniformity of temperature control of equipment as the research object, and tests and analyzes two corresponding logics of “unified” and “separate” of equipment heating and temperature measuring elements. The design of this part of test conditions is shown in Table 2, in which “unified” mode, 1# platinum resistance on each temperature control object is selected as the temperature feedback of closed-loop control. The condition 1~4 is the normal temperature environment, and the square plate and cylinder (heating rod) are tested under different temperature control logic conditions. During the final temperature control value of 40 ℃, 30 ℃step is set to realize the repeatability verification of temperature control effect.
[1] LI ZH W, DONG J L, LIU CH, et al. Development of thin-film thermocouple for measuring Transient high temperature on spacecraft surfaces[J].Spacecraft Environment Engineering,2017, 34(4):393-397. [2] ZHANG J B. Preparation and Properties of High Temperature Thin Film Thermocouples[D].Shang hai: Shanghai Jiao Tong University,2016. [3] WU X D. Application and Prospects of MEMS Devices for Space[J]. Micronanoelectronic technology,2012, 49(8):542.547. [4] LI ZH W, LIU Z Y,LIU CH, et al. Design and Implementation of a New Style thin Film Thermocouple Based on MEMS for Temperature Measurement on Spacecraft Surface[J]. Computer Measurement & Control, 2018, 26(6): 281-284. [5] CHEN R R, DING J, YANG S J,et al. Research fabrication and calibration of self-calibration Thin-film temperature sensor[J]. Transducer and Microsystem Technologies, 2019,38(4):114-117. [6] YANG H SH, YU M, LI SH Y, et al. STUDY ON THE THERMOPOWER AND RESISTIVITY OF A NEW SUPERCONDUCTOR MgB-2[J]. ACTA PHYSICS SINICA,2001,5(6): 1197-1199.
