A numerical simulation of jet impingement cooling in a rotating frame of reference

Author(s):  
S. LINTON ◽  
J. SHANG
Author(s):  
Elmar Gröschel ◽  
Carsten Lipfert ◽  
Wolfgang Erb ◽  
Daniel Rusch

The material temperature field of a centrifugal compressor wheel is one important factor for the life time analysis of a compressor stage. Due to increasing thermal loads of advanced compressor stages, the thermal stresses and/or material temperature levels can exceed the allowed limits for a prescribed exchange interval and cooling techniques are needed to reduce the wheel temperature. One efficient cooling technique is the air impingement cooling. Unlike in gas turbines the impingement cooling is located in the back face region of the compressor wheel. From a computational point of view this means that the impingment jet is located in the stationary frame of reference and the cooled wall is located in the rotating frame of reference. In such a case the heat transfer problem becomes unsteady. The paper introduces a novel CHT-mixing plane interface for the frame change between stationary fluid domain and rotating solid domain to overcome the intrinsic unsteadiness caused by the jet impingement. Fluid mixing plane interfaces between rotor and stator are very common in industries to exploit periodic symmetries and to avoid time consuming unsteady compuations. However, the commercial solvers do not provide a mixing plane interface between fluid and solid domains. First, the new mixing plane approach is validated for a representative test case against a time resolved computation. In the second step, the new method is applied to a compressor stage. Two operating conditions, each with three different cooling mass flows have been computed. The comparison of the wheel temperature field corresponds very well to the computational results for all operating conditions. The temperature field analysis reveals valuable information on the heat transfer in highly loaded compressor stages which can be exploited in the design process of the compressor cooling.


2011 ◽  
Vol 3 (2) ◽  
pp. 136-137
Author(s):  
Dr. M.T. Bhoite Dr. M.T. Bhoite ◽  
◽  
Kartik Jujare ◽  
Sayali Wable

Author(s):  
Ashutosh Kumar Yadav ◽  
Parantak Sharma ◽  
Avadhesh Kumar Sharma ◽  
Mayank Modak ◽  
Vishal Nirgude ◽  
...  

Impinging jet cooling technique has been widely used extensively in various industrial processes, namely, cooling and drying of films and papers, processing of metals and glasses, cooling of gas turbine blades and most recently cooling of various components of electronic devices. Due to high heat removal rate the jet impingement cooling of the hot surfaces is being used in nuclear industries. During the loss of coolant accidents (LOCA) in nuclear power plant, an emergency core cooling system (ECCS) cool the cluster of clad tubes using consisting of fuel rods. Controlled cooling, as an important procedure of thermal-mechanical control processing technology, is helpful to improve the microstructure and mechanical properties of steel. In industries for heat transfer efficiency and homogeneous cooling performance which usually requires a jet impingement with improved heat transfer capacity and controllability. It provides better cooling in comparison to air. Rapid quenching by water jet, sometimes, may lead to formation of cracks and poor ductility to the quenched surface. Spray and mist jet impingement offers an alternative method to uncontrolled rapid cooling, particularly in steel and electronics industries. Mist jet impingement cooling of downward facing hot surface has not been extensively studied in the literature. The present experimental study analyzes the heat transfer characteristics a 0.15mm thick hot horizontal stainless steel (SS-304) foil using Internal mixing full cone (spray angle 20 deg) mist nozzle from the bottom side. Experiments have been performed for the varied range of water pressure (0.7–4.0 bar) and air pressure (0.4–5.8 bar). The effect of water and air inlet pressures, on the surface heat flux has been examined in this study. The maximum surface heat flux is achieved at stagnation point and is not affected by the change in nozzle to plate distance, Air and Water flow rates.


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