Numerical Simulation Of Cylindrical-array On Wall Temperature&combustion Characteristics For Micro-TPV Combustor

As one kind of the Power MEMS,micro-TPV are characteristic of its various advantages,such as short energy conversion process,no moving part,easy to maintain and in accordance with the characteristics of high S/V and heat loss in micro combustor.Based on the current research of heat transfer enhancement in micro combustor,a new type micro combustor of heat transfer enhanced by staggered cylindrical array is proposed.A larger heat transfer area,a better convection and stagnation zones downstream of cylinder make it more appropriate micro-TPV combustor.This article extends the designing of micro-TPV combustor and is helpful to the development of Power MEMS.By means of numerical simulation with detailed reaction mechanism,the effect of the cylindrical array on heat transfer between burned gas and combustor inner wall is analyzed.In the first part research,the heat transfer effect of cylindrical array is analyzed by comparing the wall temperature characteristics of combustors with and without cylindrical array under various inlet velocity,equivalence ratio,combustor channel height and wall thermal conductivity.The results revealed that,under inlet velocity of 4m/s,the cylindrical array raises the wall temperature about 74 K and the usable radiation 9.24 W with a growth of 34.55%.And the increment increases with the growth of inlet velocity.Meanwhile,the temperature uniformity of radiation wall is improved on account of increasing minimum temperature in the cylindrical-array combustor.The cylindrical array is not only improves the wall temperature distribution,but also anchored the flame.Increasing inlet velocity from 4m/s to 16m/s,the moving distance of flame in the cylindrical-array combustor is 4.3mm which is much shorter than 9.1mm in the conventional combustor without cylindrical array.However,the moving downstream of flame under extreme equivalence ratio makes heat loss of flame worsen due to the heat transfer between flame and cylindrical array.And the stability limits of equivalence ratio in cylindrical-array combustor is only 0.5 ~ 4.5 which is slightly narrower than 0.4 ~ 6.0 in conventional-channel combustor.In the research of cylindrical array structure,the length,diameter and arrangement of cylindrical array is analyzed.The result shows that the stability limits of equivalence ratio in cylindrical-array combustor is improved to 0.3 ~ 5.5 when the length of cylindrical array is reduced to 10 mm.And the temperature uniformity of radiation wall is also improved.However,the usable radiation is reduced by 1.59 W.With the decrease of cylinder diameter,the wall temperature is increased.The wall temperature in D=0.5mm combustor is 21.3K higher than that in D=1mm combustor.And the temperature difference between wall and gas at the outlet is only 53.7K which is 80.6K lower than that in D=1mm combustor.