建筑给排水外文文献翻译

1、MX建薯土摩本科毕业设计外文文献及译文文献、资料题目： Sealed buildi ng drain ageand vent systems文献、资料来源：国道数据库文献、资料发表（出版）日期 ：2016.6 院 （部）：市政与环境工程学院专 业 :给水排水工程班 级：水工122姓 名：学 号：20120411048指导教师：翻译日期 ：2016.6外文文献:Sealed build ing drain age and vent systemsan applicati on of active air pressure tran sie nt con trol and suppressi on

2、AbstractThe in troducti on of sealed buildi ng drain age and vent systems is con sidered a viable propositi on for complex build ings due to the use of active pressure tran sie nt con trol and suppressi on in the form of air admitta nee valves and positive air pressure atte nu ators coupled with the

3、 in terc onnection of the n etwork's vertical stacks.This paper prese nts a simulati on based on a four-stack n etwork that illustrates flow mecha ni sms with in the pipework follow ing both applia nee discharge gen erated, and sewer imposed, tran sie nts. This simulati on ide ntifies the role o

4、f the active air pressure con trol devices in maintaining system pressures at levels that do not deplete trap seals.Further simulati on exercises would be n ecessary to provide proof of con cept, and it would be adva ntageous to parallel these with laboratory, and possibly site, trials for validatio

5、n purposes. Despite this caution the initial results are highly en courag ing and are sufficie nt to confirm the pote ntial to provide defi nite ben efits in terms of enhanced system security as well as in creased reliability and reduced in stallati on and material costs.Keywords: Active con trol; T

6、rap rete nti on; Tran sie nt propagati onNome nclatureC+-characteristic equati onscwave speed, m/sDbranch or stack diameter, mffriction factor, UK definition via Darcy Ah=4fLu 2/2Dggaccelerati on due to gravity, m/s2Kloss coefficie ntLpipe len gth, m2pair pressure, N/mttime, sumean air velocity, m/s

7、xdista nee, myratio specific heatshhead loss, m2ppressure differe nee,N/mttime step, sxinterno dal len gth, m3pden sity, kg/mArticle Outli neNome nclature1. In troducti on air pressure tran sie nt con trol and suppressi on2. Mathematical basis for the simulati on of tran sie nt propagati on in multi

8、-stack build ing dra in age n etworks3. Role of diversity in system operati on4. Simulati on of the operati on of a multi-stack sealed buildi ng drain age and vent system5. Simulati on sig n conven tio ns6. Water discharge to the n etwork7. Surcharge at base of stack 18. Sewer imposed tran sie nts9.

9、 Trap seal oscillation and retention10. Con clusi onviability of a sealed buildi ng dra in age and vent system1. Air pressure tran sie nts gen erated with in buildi ng dra in age and vent systems as a n atural con seque nee of system operation may be responsible for trap seal depletion and cross con

10、tamination of habitable space 1. Traditi onal modes of trap seal protect ion, based on the Victoria n engin eer's obsessi on with odour exclusi on 2, 3 and 4, depend predominantly on passive solutions where relianee is placed on cross connections and vertical stacks ven ted to atmosphere 5 and 6

11、. This approach, while both prove n and traditi on al, has in here nt weak nesses, in cludi ng the remote ness of the vent termi natio ns 7, leadi ng to delays in the arrival of reliev ing reflect ions, and the multiplicity of ope n roof level stack termi natio ns in here nt within complex buildi ng

12、s. The complexity of the vent system required also has significant cost and space implications 8.The developme nt of air admitta nee valves (AAVs) over the past two decades provides the desig ner with a means of alleviati ng n egative tran sie nts gen erated as ran dom applia nee discharges con trib

13、ute to the time depe ndent water-flow con diti ons withi n the system. AAVs represe nt an active con trol soluti on as they resp ond directly to thelocal pressure con diti ons, ope ning as pressure falls to allow a relief air inflow and hence limit the pressure excurs ions experie need by the applia

14、 nee trap seal 9.However, AAVs do not address the problems of positive air pressure tran sie nt propagati on with in build ing drain age and vent systems as a result of in termitte nt closure of the free airpath through the n etwork or the arrival of positive tran sie nts gen erated remotely with in

15、 the sewer system, possibly by some surcharge event dow nstream in cludi ng heavy rain fall in comb ined sewer applicati ons.The developme nt of variable volume containment atte nu ators 10 that are desig ned to absorb airflow drive n by positive air pressure tran sie nts completes the n ecessary de

16、vice provisi on to allow active air pressure tran sie nt con trol and suppressi on to be in troduced into the desig n of build ing drain age and vent systems, for both standard' Idiuigs and those requiring particular attention to be paid to the security implications of multipleroof level ope n s

17、tack term in atio ns. The positive air pressure atte nu ator (PAPA) con sists of a variable volume bag that expa nds un der the in flue nee of a positive tran sie nt and therefore allows system airflows to atte nu ate gradually, therefore reduci ng the level of positive tran sie nts gen erated. Toge

18、ther with the use of AAVs the in troducti on of the PAPA device allows con siderati on of a fully sealed buildi ng drain age and vent system.Fig. 1 illustrates both AAV and PAPA devices, note that the waterless sheath trap acts as an AAV under n egative line pressure.:Fig. 1. Active air pressure tra

19、n sie nt suppressi on devices to con trol both positive and n egative surges.Active air pressure tran sie nt suppressi on and con trol therefore allows for localized in terve nti on to protect trap seals from both positive and n egative pressure excurs ions. This has disti net adva ntages over the t

20、raditi onal passive approach. The time delay in here nt in await ing the return of a relievi ng reflect ion from a vent ope n to atmosphere is removed and the effect of the transient on all the other system traps passed during its propagation is avoided.2. Mathematical basis for the simulati on of t

21、ran sie nt propagati on in multi-stack buildi ng drain age n etworks.The propagati on of air pressure tran sie nts with in build ing drain age and vent systems bel ongs to a well un derstood family of un steady flow con diti ons defi ned by the St Venant equati ons of continuity and mome ntum, and s

22、olvable via a fin ite differe nee scheme utiliz ing the method of characteristics tech niq ue. Air pressure tran sie nt gen erati on and propagati on with in the system as a result of air entrainment by the falli ng annu lar water in the system vertical stacks and the reflect ion and tran smissi on

23、of these tran sie nts at the system boun daries, in clud ing ope n term in ati ons, connections to the sewer, applia nee trap seals and both AAV and PAPA active con trol devices, may be simulated with proven accuracy. The simulation 11 provides local air pressure, velocity and wave speed information

24、 throughout a network at time and distance intervals as short as 0.001 s and 300 mm. In addition, the simulation replicates local appliance trap seal oscillations and the operation of active control devices, thereby yieldi ng data on n etwork airflows and ide ntify ing system failures and con seque

25、nces. While the simulatio n has bee n exte nsively validated 10, its use to in depe nden tly confirm the mecha nism of SARS virus spread within the Amoy Garde ns outbreak in 2003 has provided further con fide nce in its predict ions 12.Air pressure transient propagation depends upon the rate of chan

26、ge of the system conditions. Increasing annu lar dow nflow gen erates an enhanced entrained airflow and lowers the system pressure. Retardi ng the entrained airflow gen erates positive tran sie nts. External events may also propagate both positive and n egative tran sie nts into the n etwork.The ann

27、ular water flow in the wet ' stack entrains an airflow due to the condition of no slip ' established betwee n the annu lar water and air core surfaces and gen erates the expected pressure variati on dow n a vertical stack. Pressure falls from atmospheric above the stack en try due to frictio

28、 n and the effects of draw ing air through the water curta ins formed at discharg ing branch junctions. In the lower wet stack the pressure recovers to above atmospheric due to the tract ion forces exerted on the airflow prior to falli ng across the water curta in at the stack base.The applicatio n

29、of the method of characteristics to the modelli ng of un steady flows was first recog ni zed in the 1960s 13. The relationships defined by Jack 14 allows the simulation to model the traction force exerted on the entrained air. Extensive experimental data allowed the definition of a-friction factor &

30、#39;applicasledio thewet stack and operable across the water annu lar flow/e ntrained air core in terface to allow comb ined discharge flows and their effect on air entrainment to be modelled.The propagati on of air pressure tran sie nts in buildi ng drain age and vent systems is defi ned by the St

31、Venant equatio ns of continuity and mome ntum 9,rSu/Sx + 2/(y l)c 2c/8t + u£c/£x = Q,(1)|2/(y l)c0c/6i + 9u/6t + u3u/&l+ 4fa | u |/2D = 0-(2)Lqii.ilNHihliinc. ILi 心 i：vtiflp) nrQ=rtO eK.These quasi-linear hyperbolic partial differential equations are amenable to finite difference solut

32、ion once tran sformed via the Method of Characteristics into fin ite differe nce relati on ships, Eqs. (3) (6), that link con diti ons at a node one time step in the future to curre nt con diti ons at adjace nt upstream and dow nstream no des, Fig. 2.Bi iirhiryCUflditkil) Ln bewilved w iihi-hnnii hr

33、ri、li,at boundarh.Fig.2. St Venant equations of continuity and momentum allow airflow velocity and wave speed to be predictedon an x-t grid as shown. Note < . IQ ,兰一 -：.For the C+ characteristic:2、Atup nu 4-孑 (c? cr) -k 4f 口以 |ur | = Q(3)whe n(4)and the C characteristic:Sup us 1 fcp 磚)+ 就= 9>1

34、whe n|(6)|where the wave speed c is give n byc=( Y p p)0'5.These equations involve the air mean flow velocity, u, and the local wave speed, c, due to the interdependence of air pressure and den sity. Local pressure is calculated asPZL = Kp昨巾扁附血呼加叫(8)Suitable equati ons link local pressure to air

35、flow or to the in terface oscillati on of trap seals.The case of the applia nee trap seal is of particular importa nee. The trap seal water colu mn oscillates un der the action of the applied pressure differential between the transients in the network and the room air pressure. The equation of motio

36、n for the U-bend trap seal water column may be written at any time as+ pg (AH5_a - dH)-ApF = (mJAT)Au/At(9)It should be recognized that while the water column may rise on the appliance side, conversely on the system side it can never exceed a datum level drawn at the branch connection.In practical t

37、erms trap seals are set at 75 or 50 mm in the UK and other international standards dependent upon appliance type. Trap seal retention is therefore defined as a depth less than the initial value. Many standards, recog nizing the tran sie nt n ature of trap seal depleti on and the opport un ity that e

38、xists for re-charge on applia nce discharge allow 25% depleti on.The boun dary equatio n may also be determ ined by local con diti ons: the AAV ope ning and subseque nt loss coefficie nt depe nds on the local li ne pressure predicti on.Empirical data identifies the AAV opening pressure, its loss coe

39、fficient during opening and at the fully open con diti on. Applia nce trap seal oscillati on is treated as a boun dary con diti on depe ndent on local pressure. Deflect ion of the trap seal to allow an airpath to,or from, the appliance or displacement leading to oscillation alone may both be modelle

40、d. Reduct ions in trap seal water mass duri ng the tran sie nt in teracti on must also be in cluded.3. Role of diversity in system operati onIn complex buildi ng drain age n etworks the operati on of the system applia nces to discharge water to the n etwork, and hence provide the con diti ons n eces

41、sary for air entrainment and pressure tran sie nt propagati on, is entirely random. No two systems will be identical in terms of their usage at any time. This diversity of operation implies that in ter-stack venting paths will be established if the in dividual stacks withi n a complex buildi ng n et

42、work are themselves interconnected. It is proposed that this diversity is utilized to provide venting and to allow serious con siderati on to be give n to sealed drain age systems.In order to fully impleme nt a sealed buildi ng drain age and vent system it would be n ecessary for the n egative tran

43、sie nts to be alleviated by draw ing air into the n etwork from a secure space and not from the exter nal atmosphere. This may be achieved by the use of air admitta nee valves or at a predeterm ined locati on with in the build ing, for example an accessible loft space.Similarly, it would be n ecessa

44、ry to atte nu ate positive air pressure tran sie nts by means of PAPA devices.In itially it might be con sidered that this would be problematic as positive pressure could build with in the PAPA installations and therefore negate their ability to absorb transient airflows. This may again be avoided b

45、y linking the vertical stacks in a complex build ing and utiliz ing the diversity of use in here nt in buildi ng dra in age systems as this will ensure that PAPA pressures are themselves alleviated by allowing trapped air to vent through the in terc onn ected stacks to the sewer n etwork.Diversity a

46、lso protects the proposed sealed system from sewer drive n overpressure and positive tran sie nts. A complex building will be interconnected to the main sewer network via a number of connecting smaller bore drains. Adverse pressure con diti ons will be distributed and the n etwork in terc onnection

47、will continue to provide venting routes.These con cepts will be dem on strated by a multi-stack n etwork.4. Simulati on of the operati on of a multi-stack sealed buildi ng drain age and vent systemFig. 3 illustrates a four-stack network. The four stacks are linked at high level by a manifold leading

48、 to a PAPA and AAV in stallati on. Water dow nflows in any stack gen erate n egative tran sie nts that deflate the PAPA and ope n the AAV to provide an airflow into the n etwork and out to the sewer system. Positive pressure gen erated by either stack surcharge or sewer tran sie nts are atte nu ated

49、 by the PAPA and by the diversity of use that allows one stack-to-sewer route to act as a relief route for the other stacks.The n etwork illustrated has an overall height of 12m. Pressure tran sie nts gen erated with in the n etwork will approximately 0.08s and from stack base to stack base of appro

50、ximately 0.15pagate at the acoustic velocity in airThis implies pipe periods, from stack base to PAPA ofIn order to simplify the output from the simulation no local trap seal protection is included for example the traps could be fitted with either or both an AAV and PAPA as examples of active c

51、on trol. Traditi onal n etworks would of course in clude passive venting where separate vent stacks would be provided to atmosphere, however a sealed buildi ng would dispe nse with this venting arra ngeme nt.All pipri 0.1 rfi durncier,I and 3只;irl 8L4JT1U IfiN.mii ?1Pipesll-U. H-l7, 19-22,；il* 加i k&

52、#39;tig們严d. IX Z Arid空竺一Dtiid EetdjJP4Fig.3.Four stack buildi ng drain age and vent system to dem on strate the viability of a sealed buildi ng system.Ideally the four sewer connections shown should be to separate collection drains so thatdiversity in the sewer network also acts to aid system self v

53、enting. In a complex building this requirement would not be arduous and would in all probability be the no rm. It is en visagedthat the stack connections to the sewer n etwork would be distributed and would be to a below gro und dra in agen etwork that i ncreased in diameter dow nstream. Other conne

54、ctions to then etwork would in all probability be from buildi ngs that in cluded the more traditi onal ope n vent system desig n so that a further level of diversity is added to offset any dow nstream sewer surcharge eve nts of long duratio n. Similar con siderati ons led to the curre nt desig n gui

55、da nee for dwelli ngs.It is stressed that the n etwork illustrated is represe ntative of complex buildi ng drain age n etworks. Thesimulati on will allow a range of applia nee discharge and sewer imposed tran sie nt con diti ons to be in vestigated.The follow ing applia nee discharges and imposed se

56、wer tran sie nts are con sidered:1. w.c. discharge to stacks - 3 over a period 1 - 6s and a separate w.c. discharge to stack 4 between 2 and 7s.2. A minimum water flow in each stack continues throughout the simulation, set at O.IL/s, to represent trailing water following earlier multiple appliance d

57、ischarges.3. A 1s duratio n stack base surcharge event is assumed to occur in stack 1 at 2.5s.4. Seque ntial sewer tran sie nts imposed at the base of each stack in tur n for 1.5s from 12 to 18s.The simulatio n will dem on strate the efficacy of both the con cept of active surge con trol and in ter-

58、stack ven ti ng in en abli ng the system to be sealed, i.e. to have no high level roof pen etrati ons and no vent stacks ope n to atmosphere outside the buildi ng en velope.The imposed water flows within the network are based on real ' system values, being representative of current w.c. discharge characteristics in terms of peak flow, 2l/s, overall volume, 6l, and duration, 6s. The sewer tran sie nts at 30mm water gauge are represe ntative but not exc