【正文】 ater flows in each stack. 9. Trap seal oscillation and retentionThe appliance traps connected to the network monitor and respond to the local branch air pressures. The model provides a simulation of trap seal deflection, as well as final retention. Fig. 11(a,b) present the trap seal oscillations for one trap on each of the stacks 1 and 2, respectively. As the air pressure falls in the network, the water column in the trap is displaced so that the appliance side water level falls. However, the system side level is governed by the level of the branch entry connection so that water is lost to the network. This effect is illustrated in both Fig. 11(a) and (b). Transient conditions in the network result in trap seal oscillation, however at the end of the event the trap seal will have lost water that can only be replenished by the next appliance usage. If the transient effects are severe than the trap may bee totally depleted allowing a potential cross contamination route from the network to habitable space. Fig. 11(a) and (b) illustrate the trap seal retention at the end of the imposed network transients..(a) Trap seal oscillation, trap 2. (b) Trap seal oscillation, trap 7.Fig. 11(a), representing the trap on pipe 2, illustrates the expected induced siphonage of trap seal water into the network as the stack pressure falls. The surcharge event in stack 1 interrupts this process at 2s. The trap oscillations abate following the cessation of water downflow in stack 1. The imposition of a sewer transient is apparent at 12s by the water surface level rising in the appliance side of the trap. A more severe transient could have resulted in ‘bubbling through’ at this stage if the trap system side water surface level fell to the lowest point of the Ubend. The trap seal oscillations for traps on pipes 7, Fig. 11(b) and 15, are identical to each other until the sequential imposition of sewer transients at 14 and 16s. Note that the surcharge in pipe 1 does not affect these traps as they are remote from the base of stack 1. The trap on pipe 20 displays an initial reduction in pressure due to the delay in applied water downflow. The sewer transient in pipe 19 affects this trap at around 18s. As a result of the pressure transients arriving at each trap during the simulation there will be a loss of trap seal water. This overall effect results in each trap displaying an individual water seal retention that depends entirely on the usage of the network. Trap 2 retains 32mm water seal while traps 7 and 15 retain 33mm. Trap 20 is reduced to 26mm water seal. Note that the traps on pipes 7 and 15 were exposed to the same levels of transient pressure despite the time difference in arrival of the sewer transients. Fig. 11(a) and (b) illustrate the oscillations of the trap seal column as a result of the solution of the trap seal boundary condition, Eq. (10), with the appropriate C+ characteristic. This boundary condition solution continually monitors the water loss from the trap and at the end of the event yields a trap seal retention value. In the example illustrated the initial trap seal values were taken as 50mm of water, mon for appliances such as .39。s and sinks. 10. Conclusion—viability of a sealed building drainage and vent systemThe simulation presented confirms that a sealed building drainage system utilizing active transient control would be a viable design option. A sealed building drainage system would offer the following advantages: ? System security would be immeasurably enhanced as all highlevel open system terminations would be redundant.? System plexity would be reduced while system predictability would increase.? Space and material savings would be achieved within the construction phase of any installation.These benefits would be realized provided that active transient control and suppression was incorporated into the design in the form of both AAV to suppress negative transients and variable volume containment devices (PAPA) to control positive transients. The diversity inherent in the operation of both building drainage and vent systems and the sewers connected to the building have a role in providing interconnected relief paths as part of the system solution. The method of characteristics based finite difference simulation presented has provided output consistent with expectations for the operation of the sealed system studied. The accuracy of the simulation in other recent applications, including the accurate corroboration of the SARS spread mechanism within the Amoy Gardens plex in Hong Kong in 2003, provides a confidence level in the results presented. Due to the random mode of operation of building drainage and vent systems further simulations, laboratory and site investigations will be undertaken to ensure that the concept is wholly viable. 32中文譯文：密封的建筑排水系統(tǒng)和通氣系統(tǒng)——活性氣壓的瞬變控制和抑制摘要由于通過成對的吸氣閥和正壓衰減器與管網中的立管互相連接能控制和抑制活性氣壓瞬變，因此在綜合樓中采用密封的建筑排水系統(tǒng)和通氣系統(tǒng)被認為是一個可行的提議。文章通過四根立管提出一種模擬實驗，說明了瞬時產生和加強的氣壓在排水管中的流動機制。這種模擬實驗在水封不被破壞，系統(tǒng)壓力得以維持的條件下，能夠辨認活性氣壓控制設備的作用。系統(tǒng)安全性提高、可靠性增加且設施和材料費減少，可見這種最初結果是令人高度鼓舞的，且足以證實潛在的明確利益，但進一步的模擬實驗有必要提供概念上的證明，且它與其他以檢驗為目的的實驗室、可能的地方、試驗相比是有利的。關鍵詞：活性氣壓控制，存水彎保持，瞬變傳播。命名原則C+——特征方程c——波速, m/s D——分支或堆積直徑, m f——摩擦因子， 英國定義通過Darcy Δh=4fLu2/2Dg g——重力加速度, m/s2 K——損失系數(shù)L——管長, m p——壓力, N/m2 t——時間, s u——空氣速度, m/s x——距離, mγ——比熱率Δh——水頭損失, m Δp——壓力差, N/m2 Δt——時間間隔, s ρ——密度, kg/m3目錄命名原則――瞬時氣壓的控制和抑制。6．排入管網的水7．立管1底部排水8．瞬時氣壓強加于污水管9．水封的振動和保持——密封建筑排水和通氣系統(tǒng)的可行性――瞬時氣壓的控制和抑制作為系統(tǒng)操作的自然結果，建筑排水系統(tǒng)和通氣系統(tǒng)內部產生的氣壓瞬變對于水封破壞和交叉污染的可居住空間來說也是可靠的。[1]水封保護的傳統(tǒng)模式，基于維多利亞女王時代的工程師對氣味排除的觀念[2]、[3]和[4]，通過交叉連接和立管排入大氣[5]和[6]，主要取決于信任基礎上的消極的解決方法。這種方法盡管既被證明了，也是傳統(tǒng)的，但也有其內在弱點，如通氣管末端較遠[7]，導致了綜合樓緩解反應到達較遲和敞開屋面立管末端內在的多樣性。復雜的通氣系統(tǒng)需要大量費用且于空間有密切聯(lián)系[8]。在過去20年里，吸氣閥（AAVs）的發(fā)展給設計師提供了一種緩解瞬時負壓的方法，如在隨機的潔具排水過程中，吸氣閥有助于系統(tǒng)中水力條件的恢復。當吸氣閥直接反映本地壓力條件時，它們代表了一種控制活性氣壓的解決方法，它們自動打開，使新鮮空氣進入管道系統(tǒng)，從而使系統(tǒng)的壓力得到平衡并保護了冰封[9]。然而，吸氣閥不能解決建筑排水系統(tǒng)和通氣系統(tǒng)中瞬時正壓傳播的問題，污水管網中自由水流或遠處產生的瞬時正壓的到達通路間歇的關閉，