Compressor of centrifugal type air

One, foreword Compressor of centrifugal type air belongs to compressor of dynamical formula air. Its work basically the principle is to use impeller of high speed revolving to promote aeriform element kinetic energy, repass diffuser makes the pressure of kinetic energy translate into of aeriform element can. It has capacity big, efficiency is tall, the structure is simple, volume is minor, gas does not get the movement below oily pollution and normal operating mode smooth, compress air current to not have pulsatile wait for a characteristic. However, compressor of centrifugal type air is more sensitive to change of aeriform pressure, discharge, temperature, easy happening asthma brace up. Special when summertime air temperature is high, breathe heavily brace up phenomenon particularly frequent. 2, breathe heavily brace up mechanism Breathe heavily brace up the periodic oscillation that is the medium in fluid machinery and its conduit, it is medium gets periodic inspiratory the machine that produces with the prompt action of eduction is oscillatory. To centrifugal, breathe heavily brace up it is one of common breakdown in compressing accident to go, it is to rotate the further progress of stall. Fixed rate is lowered in bear when centrifugal type compressor when, gas be compressioned will be formed in the non-working surface of impeller shed a group, cause concussion loss to increase quickly, this makes discharge loss increases not only, efficiency drops, still can bring about air current to answer compressor from tubal net, cause airframe intense oscillation, give out ” asthma ” or ” to roar ” sound, the ” that this kind of phenomenon calls centrifugal type compressor breathes heavily brace up ” . If the graph is shown 1 times, centrifugal type compressor has such character, to a certain rotate speed, total correspondence sheds value of a quantity, compressor efficiency reachs culmination. When discharge is more than or be less than this value, efficiency will drop. Often be dot of design operating mode with the operating mode dot of this discharge commonly. The function curve left of compressor is breathed heavily brace up operating mode (the limitation of Qmin) , right is jammed the limitation of operating mode, in the area between this both, call the area of steady working condition of compressor. The size of area of steady working condition, it is the main index that measures compressor performance.

In running a course when compressor, when if make because of exterior reason discharge is reduced ceaselessly,achieving Qmin to be worth, can appear in compressor flow path serious whirl is broken away from, if tolerance decreases Xiaoshi further, the whole flow path of compressor impeller by air current vortical area place is held, at this moment the outlet pressure of compressor will drop suddenly. But, connective of compressor exit place relatively the pressure in the system tubal a network of high capacity does not drop immediately, the phenomenon that right now the gas in net of meeting occurrence canal flows backwards to compressor. Drop to export exhaust pressure under compressor when force of middling pressure tubal a network when, gas flows backwards can stop, compressor restores again to exhaust tubal a network. However, because enter the inadequacy of tolerance, after compressor is in charge of a net to renew original pressure in exit, can appear inside flow path again vortical area. Such go round and round, the discharge inside aircrew and conduit can produce periodic change, pressure of machine imports and exports is met substantially pulsatile. In compressor as a result of gas place of imports and exports takes in and send out in large quantities flow backwards, can accompany have tremendous periodic air current roaring and acuteness machine vibration, these wave motion are operated in appearance dish pressure, discharge, oscillatory signal shows, can mirror clearly in the record come out, in the operation the spot also can become aware instantly get. By asthma brace up closely related the machine vibration frequency that cause, amplitude and size of cubage tubal a network, volume tubal a network is larger, rate of asthma Zhen Pin is lower, amplitude is bigger. The vent-pipe net size of a few machines is very large, right now rate of asthma Zhen Pin is less than 1Hz even. 3, cause machine of centrifugal type pneumatics to breathe heavily brace up reason At present the empty press inside station of my company pneumatics is machine of pneumatics of machine of pneumatics of ELLIOTT 1100DA3 centrifugal type and P700 centrifugal type. Machine of these two kinds of pneumatics has automatic double mode to control: The force of platoon atmospheric pressure of pneumatics machine is by set on the pressure value that place of a certain system needs, entrance adjustment guide vane (IGV) in pneumatics machine adjustable limits internal energy adjusts entrance tolerance, make pneumatics machine retains power of constant platoon atmospheric pressure. Should arrive at asthma brace up after reference point, entrance guide vane stops to close small, make the force of platoon atmospheric pressure of pneumatics machine rises to uninstall pressure set point, right now pneumatics machine will be uninstalled (entrance adjustment guide vane (IGV) shut, put empty a powerful person (BOV) is opened) . Pneumatics machine will maintain all the time uninstall condition be worth under the least pressure of set till exhaust pressure. Next pneumatics aircraft moves new to load to full discharge, begin a new circulation again. And in actual production moving process is not such, cause machine of centrifugal type pneumatics to breathe heavily among them brace up the element is very much, reduce the following respects: 3.1 produce asthma brace up main reason is the spot reduces air dosage lesser or the metabolic amount that the spot reduces air dosage is larger. Make when the spot compresses air to make dosage lesser compressor exports hold back to press easily, gas flows into compressor, create low flow of the gas inside machine; The negative charge that reduces the machining complex when air makes dosage bigger when the spot increases, compressor is carried not in time fast. A powerful person of 3.2 entrances guide vane (IGV) not movement or a powerful person of entrance guide vane (IGV) most bit set value is lesser. When increasing with tolerance, entrance guide vane drives the demand that spends short of operating mode, the entrance discharge of pneumatics machine decreases, and entrance discharge decreases to bring about pneumatics plane load to decrease directly, cannot furnish in time the spot uses tolerance, can cause asthma brace up; Put empty a powerful person (BOV) cannot be opened or put empty a powerful person (BOV) close career too fast. Put empty a powerful person cannot be opened in time or shut speed to make pneumatics machine exports hold back to press too quickly, gas flows into pneumatics machine, create low flow of the gas inside machine. The 2 class of machine of pneumatics of 3.3 centrifugal type or inlet temperature of 3 class entrance are exorbitant. When lifting as a result of inlet temperature, curve of pneumatics plane performance falls right move, rise to step up comparing to be less than asthma when temperature when Zhen Sheng pressure ratio, can produce asthma brace up. Do 3.4 entrances and exit atmospheric pressure differ: ? This? entrance and exit atmospheric pressure differ word fear to jump over incidental asthma greatly more brace up. Enter the mouth that is to say pressure is lower, pneumatics machine jumps over incidental asthma brace up, and outlet pressure jumps over incidental asthma higher brace up. The most serious breakdown that 3.5 impeller wear away or attaint pneumatics machine appears is impeller wear away or damage, and this kind of circumstance indissolubles in pneumatics machine is judged hard when body, accordingly, judgement of this kind of circumstance has certain difficulty. 4, be on guard measure 4.1 ensure the user uses tolerance smooth. Establish corresponding call mechanism, discover unfavorable climate is contacted in time try to adjust, make compress wave motion of air system pressure to be in can accuse limits inside, won’t happen with tolerance ignore big ignore small. Of machine of pneumatics of 4.2 pairs of centrifugal type prevent asthma brace up parameter is adjusted appropriately. Production of union of machine, report, technologist discusses the proposal that links manufacturer actually seriously, adjust a powerful person of entrance guide vane (IGV) most bit set value, reduce the risk with entrance discharge, low pressure; Adjust put empty a powerful person (BOV) shut answer speed, requirement of combinative system operating mode is adjusted commonly between 15-20 second, reduce pneumatics machine to export the occurence rate that hold back controls. 4.3 filter into gas the obstruction of the dirty filter that take energy of life should be core be less than 200 Pa, the filter core of filter is too dirty can make air sheds road block, make pneumatics machine produces asthma brace up. Although can undertake backflushing to filter core,be in in use process, but time still meets those who affect filter core for a long time filter precision, should differ a circumstance to change in time according to pressing so filter core, assure the quality of filter core. The inlet temperature between 4.4 class causes the reason with the exorbitant temperature between class too high to have: The pressure of too tall, cooling water crosses the temperature of cooling water the intermediate condenser of machine of low, pneumatics is dirty etc. Among them, the temperature between class is exorbitant be often uncared-for element, the wing that basically is the condenser intermediate piece cross air side and copper pipe to crossed cooling water side to arise dirty, , the heat that brings about condenser exchanges the effect to reduce. If be cooling water side dirty, can use cooling water recoil to wash, the result is bad to use chemical loop recoil to wash further, but must notice those who clean an agent to choose, the frequency that control cleans (the should control clear lotion strictly P H cost when cleaning, prevent acid too strong, corrode the housing) of pneumatics machine; If be a wing piece air side is dirty, criterion must condenser disintegrate, in immersing to be worth heating solution in appropriate PH, wash till spoil till. 4.5 after by cycle and pneumatics machine vibration condition undertakes pneumatics aircraft moves full 8000h overhauling maintaining checking impeller to be in, wait for the cracking circumstance of core parameter according to equipment vibration, undertake periodic overhaul maintains, the key checks impeller, diffuser, bearing to wait to whether have wear away, clearance whether to wait in normal limits value. Epilogue Through be opposite centrifugal pneumatics machine breathes heavily brace up analysis and research, people has realised asthma gradually brace up the inherent character that is centrifugal pneumatics machine, and be in manufacturing moving process happen possibly at any time. For this, through many practice and exploration, to breathing heavily brace up mechanism and the academic research that evolved into a process to undertake iteration and experiment analysis, sum up and induce an a lot of precaution and control asthma brace up method and experience. Accordingly, breathe heavily brace up it is to be able to be forecasted with pilot, and know and be mastered by people.