تعیین توزیع شعاعی دما و سرعت در شعله به وسیله ترموکوپل

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه پیشرانش، دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف، تهران، ایران

2 خیابان ازادی- دانشگاه صنعتی شریف- دانشکده هوافضا

3 واحد احتراق، شرکت مهندسی و ساخت توربین مپنا(توگا)

چکیده

امروزه، استفاده از ترموکوپل با جنس مقاوم و نقطه ذوب بالا به­ عنوان ابزاری کارآمد و ارزان برای اندازه­ گیری دمای گازهای داغ در احتراق استفاده می­شود. اندازه­گیری دما توسط ترموکوپل دارای خطای ذاتی ناشی از اتلاف تابشی و هدایتی است و لازم است این خطا اصلاح شود. در این پژوهش، ابتدا، با استفاده از روش عددی ترموکوپل مدل­سازی  می­ شود و صحت کد اولیه، با مقایسه نتایج پژوهش­ های پیشین، اعتبارسنجی می‌شود‌. سپس، اثر، قطر ترموکوپل و سرعت متوسط جریان بر مقدار خطای ترموکوپل بررسی می ­شود. نتایج نشان می­دهد، با افزایش قطر ترموکوپل از 5/0 به 1 میلی­متر، خطا 50 درصد افزایش یافته و با افزایش سرعت متوسط جریان از 1 به 5 متر بر ثانیه، خطا 41 درصد کاهش می یابد. در مقایسه با داده­ های یک کار تجربی، نتایج مدل­سازی ترموکوپل نشان می­ دهد که بیشینه مقدار خطا برای ترموکوپل 300 و 500 میکرونی در شرایط مورد بررسی به­ ترتیب برابر 30/8 و 39/6 درصد است. در ادامه پژوهش، الگوریتمی به­ منظور محاسبه توزیع شعاعی همزمان دما و سرعت جریان پیشنهاد شده و نتایج بیانگر دقت قابل قبول این الگوریتم برای شرایط جریان با دمای بالاست. نتایج مربوطه نشان می­دهد که خطای الگوریتم 2 درصد است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Determination of radial distribution of flame temperature and flame velocity by the thermocouple

نویسندگان [English]

  • Mohammad Javad Akbari 1
  • azadeh kebriaee 2
  • Alireza Ranjbaran 3
1 Aerospace Engineering Department, Shraif University of Technology
2 خیابان ازادی- دانشگاه صنعتی شریف- دانشکده هوافضا
3 Combustion Division, Tuga
چکیده [English]

Today, the use of resistant and high melting point thermocouples is considered as an efficient and inexpensive tool for measuring the temperature of hot gases produced by combustion. Temperature measurement by thermocouples has inherited errors due to the radiation loss and conduction loss. Therefore, it is necessary to correct this error. In this research, the thermocouple is firstly modeled using a numerical method. The validity of the original code is accredited by comparing the results with a similar previous study. Then, the effects of thermocouple diameter and average flow velocity are investigated on the thermocouple error. The error increases about 50% with increasing the thermocouple diameter from 0.5 to 1 mm. Besides, the error decreases about 41% with increasing the average velocity from 1 to 5 m/s. Based on a previous experimental study, the thermocouple modeling results indicate that the maximum errors for thermocouples with diameter of 300 and 500 microns are 30.8% and 39.6% in these conditions, respectively. In the following, a novel comprehensive solution is suggested to calculate the simultaneous distribution of temperature and velocity. Its results confirm that this algorithm has acceptable accuracy for high temperature flow conditions.

کلیدواژه‌ها [English]

  • Thermocouple
  • Flame temperature distribution
  • Correcting measurement error
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