Investigation Of Heat Transfer Enhancement In A Complex Ribbed Channel With Pulsating Steam Flow And Flow Analysis

With the continuous development of society,the requirements for the working efficiency of equipment in various fields have also been improved,resulting in a higher operating temperature of many equipment,even exceeding the heat-resistant temperature of the corresponding metal materials.The most notable example is that the blade of gas turbine works at a temperature much higher than that of the melting point of metal material,so the existence of cooling is very necessary.The turbulence characteristics of the fins guide the formation of vortexes to enhance the heat transfer and increase the area of the contact surface with the cooling medium;The better performance of the steam flow than the air and the auxiliary effects on the working conditions also have an optimized heat transfer effect;The introduction of pulsation to increase the degree of turbulence in the flow and weaken the effect of the boundary layer to enhance the heat transfer and so on have important guiding significance for the study of the internal cooling of the blades of the gas turbine.This paper is based on the working conditions of the blades of the gas turbine.For the blades in the environment of high temperature fluids,the lack of cooling capacity limits the improvement of the overall working ability of the gas turbine.A simplified model of the cooling channels inside the blades is established,which is obtained for simulated about cooling and heat exchange.The ability to intensify the heat transfer and the related reasons were compared and analyzed with the main method by the pulsating steam.For this purpose,the effects of different cooling media on the heat transfer enhancement of ribbed rectangular channels were compared;The effects of Reynolds numbers on heat transfer and flow conditions were studied;The effects of different channel rib angles on the heat transfer and flow conditions were compared and studied;The effects of different frequencies and amplitudes on the heat transfer and flow conditions under pulsation were compared and studied.The corresponding measuring points were set up to analyze the flow of the cooling fluid under various working conditions in the study channel and the comparative study of the heat transfer effect at each position.The results show that under the same conditions,the cooling capacity of steam is higher than that of air,and with the increase of Reynolds number,the degree of strengthening also increases.In steady state conditions,the enhanced heat transfer of steam over air can be at least 110% in all operating conditions.The heat transfer under steady state conditions is best with 60° ribs as a whole,followed by 45° and 30°.The heat transfer of the smooth surface is less than that of the ribbed surface.It is also proved that the fins has enhanced the heat transfer of the whole channel,which makes the degree of the internal fluid disorder increase,and the internal cooling capacity is enhanced when the heat transfer contact is enhanced.And at the ribbed surface,the heat exchange is gradually reduced from the central axis to the wall surface.Reynolds number,amplitude and frequency are important parameters affecting heat transfer under the condition of transient sinusoidal pulsating steam flow.Within the range of the parameters studied,the frequency of pulsating steam is increased,and the heat transfer coefficient in the channel is also increased.Similarly,the pulsation amplitude is increased,and the pulsation frequency is also increased.When the Reynolds number is small,there is a relatively weak heat transfer of relatively steady state.When the frequency is greater than 0.32 Hz,the fluctuation of the heat transfer data increases and the influence on the pipeline is serious,so the optimal value is 1.6 Hz.However,when the Reynolds number is 60000 and the frequency is 1.6 Hz,the amplitude is always proportional to heat transfer.When the value of the amplitude is 0.1 MPa,and the strengthening effect of heat transfer is close to 26%.On the basis of the above simulations,this paper designs experiments,purchases various experimental components,and builds the experimental stations,so as to carry out the experiment and verify the results of the numerical calculation.