نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه مهندسی مکانیک- دانشگاه تهران
2 گروه مهندسی مکانیک-دانشگاه تهران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Jet impingement is widely used in industry because of the highly favorable heat transfer rate it provides. Engineering applications include the annealing of metal sheets, drying of textile products, deicing of aircraft wings, and cooling of gas turbine blades and electronic components. There are several techniques used in evaluating the local convective heat transfer coefficient. Mass transfer methods have been widely used since many years ago. The heat-mass transfer analogy, in conjunction with the naphthalene sublimation technique, was used to investigate local and verage heat transfer coefficients. Thermo chromic liquid crystals have been applied extensively to heat transfer easurements. Using temperature maps obtained from liquid crystals applied to a constant heat flux surface, Newtons Law of Cooling is used to establish distributions of the convective heat transfer coefficient. However, these methods either require expensive or delicate equipment or have limitations to high temperatures or high levels of turbulence in the \u{fb02}ow. An alternative method that is also particularly suited for the investigation of jet impingement heat transfer, is the inverse heat conduction(IHC) technique. The temperature on the impingement surface is measured. It is advantageous because it can be carried out with simple, low-cost instrumentation and subsequent numerical procedures. In this technique, temperatures measured at some proper interior locations on the mpingement surface are used to estimate a thermal boundary condition. The word estimation is used here, as temperature measurements always contain noise. Tikhonovs regularization technique and Becks function estimation method are among the most well-known approaches in inverse heat transfer. The purpose of this study is to use the solution of a transient, sequential IHC scheme to estimate the distribution of the steady-state and unsteady onvective heat transfer coefficient in a pulsating jet in laminar flow and turbulence flow at different frequencies, and present the optimum simulation. The method is required to be considered two-dimensional because of the lateral conduction that occurs between the warmer and cooler areas of the surface of the target plate. The inverse scheme used is tested using simulated measured temperatures containing Gaussian noise.
کلیدواژهها [English]
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