【摘要】 本文提出一种采用复合冷却的加力燃烧室壁温的计算方法,附有算例,提供了加力燃烧室隔热屏设计的传热计算方法。更多还原

【Abstract】 This paper presents a method for calculating wall temperatures of a heatshield of an afterburner with convective and film cooling. The sketch of a cooling system of the afterburner is represented in fig. 6of ref. [1]. The outside wall and a concentric heat shield form an annularcooling passage. The front portion of heat shield is made of single-wall coolingsections; and the rear portion, of double-wall cooling sections. The cooling airflows through the annular passage to afford convective cooling for externalsurface of the heat shield, and it flows through the cooling slots between wallsto afford film cooling for internal surface of the heat shield. Temperatures to be evaluated are wall temperatures t_s, t₄, t_o, and thecooling-air temperature T_c, which are marked in fig. 1. The heat balance equation to evaluate t_s is as follows: t_c⁴σ(e_sw+e’_sα_g)+t_s(h_gs+h_sc)=σe’_se_gT_g⁴+h_gsT_wg+σe_awT_c⁴+h_scT_c （1） Rearranging equation （1） gives y（t_s/Z）⁴+（t_s/Z）=1 （2）where Z=(0.4819×10^-7e_gT_g⁴ + h_gsT_wg + 0.5669×10^-7e_swT_c⁴+h_scT_c)/(h_gs+h_sc) （3） y=[0.5669×10^-7Z³(e_sw+0.85α_g)]/(h_gs+h_sc （4） By introducing the formula α_g=e_g（T_g/t_s）^1.5, equations （2） and （4） can berewritten as follows: y= （1- X）/X⁴ （5） y={0.5669×10^-7Z³[e_sw+ 0.85e_gT_g^1.5/（XZ）^1.5]}/(h_gs+h_sc （6）where X = （t_S/Z）. After solving equations （5） and （6） simultaneously, the wall temperature t_smay be evaluated by the expression t_s=XZ. A similar procedure is employed in calculating the values of wall tempera-tures t_i and t_o. Two computer programs are used in this paper; one is used to calculate t_sand t_i, and the other to calculate t_o. The programs are based on finding theintersection of two curves. Since a simple method of finding the intersection oftwo curves is developed in this paper, the advantages of the programs are:simplicity, higher accuracy and less operating time. Computations of t_i, t_o, and T_c with data from reference [1] by the methodproposed in this paper are given. The calculated results agree well with thedesign data of reference [1]. The proposed calculating method of this paper appears to be superior to atedious trial-and-error procedure which is used in reference [1]. In designing heat shield of an afterburner with convective and film cooling,We must consider various designing procedures in order to obtain an optimumdesign. Much time may be saved by applying the calculating method proposedin this paper.更多还原