求助换热器设计问题？ 我这两天再找防共鸣板的例子和该结构详图，非常抱歉我居然在我的50g资料库里没有留下以前我做过的vendor's drawings. 唉，那阵子我刚有宝宝脑袋不好用了，连这个也没有备份。 防共鸣板（de-resonating baffle）是多孔的一块板使得流体的频率和设备管束的固有频率分开，通常first mode 在换热器的45%左右位置，second mode & higher 在81%换热器位置。 please refer to: https:///securel2/designmanual/dmcontent/c7.3.pdf design manuel c7.3 design lnprovements c7.3.3 • add deresonating baffles. acoustic vibration placing deresonating baffles in all heat exchanger crosspasses can noise, increase the acoustic frequency, thus eliminating any acoustic continued vibration problem. these deresonating baffles should be parallel to both the direction of crossflow and the centerline of the tubes, so that they do not materially alter the thermal and hydraulic performance of the heat exchanger. often, tubes must be removed to install deresonating baffles; installation should be done carefully to ensure that outer edges of the deresonating baffles are at least 3 to 5 in. (76 to 127 mm) from the shell. incorrect placement of deresonating baffles can seriously affect performance of heat exchangers with two-phase flow on the shell side by causing an undesirable separation of the phases. although xist does not handle deresonating baffles, a discussion is provided in stv-4 [31 and by barrington [4, 5j. a few guidelines in the literature describe the size, thickness, or placement of deresonating baffles to prevent acoustic resonance in shell-and-tube heat exchangers. chen [61 recommends dividing the exchanger with deresonating baffles to create acoustic frequencies as different from one another as possible. in this way, higher damping is achieved due to the interaction of individual chambers; any resonance is localized and the number of baffles minimized. following this recommendation, figure c7.3-1 shows that, to affect the first five modes, the best position for a single baffle is about 0.05 d off the centerline. the resulting characteristic lengths are 55 and 45 percent of the shell diameter, which are most effective in suppressing the first mode. on the other hand, if two baffles are used, they should be placed about 0.05 d on one side of the centerline and 0.32d on the other. this arrangement produces characteristic lengths of 18, 37, and 45 percent of the shell diameter. because the acoustic frequencies are inversely proportional to the characteristic length, the resulting frequencies are increased by 5.6, 2.7, and 2.2 times the acoustic frequency without the deresonating baffles. figure c7.3-1. recommended placement of deresonating baffles. blevins [7] cautions that for a deresonating baffle to be effective, it must be capable of reflecting a sound wave. such an observation implies a baffle with more mass than the surrounding shellside fluid. the baffle thickness must be greater than b b sf b x t (c7.3-1) change the shell diameter. although often not the most attractive approach, a change in the shell diameter can alter the acoustic frequency; however, it may also cause a significant and unacceptable change in the thermal and hydraulic performance of the heat exchanger. changing the shell diameter is less effective than adding deresonating baffles. avoid a frequency match. on those rare occasions when the acoustic and tube natural frequencies nearly match, the acoustic frequency should be changed by adding deresonating baffles or the tube natural frequency should be changed by shortening the maximum unsupported span length. shortening the span is more effective, if allowable pressure drop permits. c7.3.3 acoustic vibration noise, continued first deresonating baffle second deresonating baffle mode 1 2 3 4 5 0.45 d s 0.37 d s 0.18 d s 哎呀！就htri 有一份对于该软件的资料详细的介绍了htri的振动分析的warning, analysis region: https:///securel1/so ... ls/fundamentals.pdf (对不起，这是htri的copy right. 这份fundamentals 是我极力推荐给用htri的设计人员的软件入门资料，必读。) i recommend a paper for heat exchanger accoustic vib:查看更多
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