Hadała, Beata
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inżynieria materiałowa
inżynieria mechaniczna
inżynieria mechaniczna
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Item type:Doctoral Dissertation, Access status: Open Access , Wymiana ciepła w procesach kucia swobodnego odkuwek(2004-04-20) (Data obrony: 2007) Hadała, Beata
Wydział Inżynierii Metali i Informatyki PrzemysłowejOpen die forging belongs to processes of the plastic working, in which heat transfer, characterized by the heat transfer coefficient between material being deformed and the anvil and the air, is a function of many variables. At doctor's thesis an attempt was made to determine the size of the heat transfer coefficient depending on size of the contact surface area between the forging and the anvil, degree of deformation, presence of primary scale, increase of the secondary scale during the forging operation, thermal resistance of anvil surface and temperature of material. The heat generation as a result of the work of the plastic strain was also taken into consideration. Thanks to applying numerical modeling, verified experimentally through thermovision measurements determining the forging surface temperature and temperature distribution in the cross section, value of heat transfer coefficient was determined. It ranges from 310 to 450 W / (m2 •K). A considerable influence was stated to its size depending on the thickness of the scale on the surface and the anvil. Also a slight influence of the contact surface between the forging and the anvil to the surface temperature of the forging was determined and no impact on the temperature field in the cross section of material. An also slight increase of the material temperature was observed in the consequence of plastic strain.Item type:Article, Access status: Open Access , Identification of the average and local boundary condition of heat transfer during cooling with a water spray under surface boiling(Wydawnictwa AGH, 2020) Jasiewicz, Elżbieta; Hadała, Beata; Malinowski, ZbigniewThe study determined the local and average heat transfer coefficient and the heat flux on the surface of a cylinder cooled with a water nozzle. The inverse method was used to identify the heat transfer coefficient. An objective function was defined to determine the distance between the measured and calculated temperatures. Two models describing the heat transfer coefficient on the cooled surface were considered. The first model described changes in the heat transfer coefficient as a function of the sample radius and cooling time, and the second one assumed the dependence of the heat transfer coefficient solely on time. Numerical simulations showed significant differences in the determined heat transfer coefficients depending on the adopted model of the boundary condition. The performed tests included experimental temperature measurements at selected points of the sensor, numerical simulations of temperature changes, and the inverse solution.Item type:Book, Access status: Open Access , Walidacja modeli i identyfikacja warunku brzegowego wymiany ciepła przy chłodzeniu natryskowym stali(Wydawnictwa AGH, 2016) Hadała, Beata