【正文】 ++4++6+5. Simulation conventionsIt should be noted that heights for the system stacks are measured positive upwards from the stack base in each case. This implies that entrained airflow towards the stack base is negative. Airflow entering the network from any AAVs installed will therefore be indicated as negative. Airflow exiting the network to the sewer connection will be negative. Airflow entering the network from the sewer connection or induced to flow up any stack will be positive. Water downflow in a vertical is however regarded as positive. Observing these conventions will allow the following simulation to be better understood. 6. Water discharge to the networkTable 1 illustrates the . discharges described above, simultaneous from 1s to stacks 1–3 and from 2s to stack 4. A base of stack surcharge is assumed in stack 1 from to 3s. As a result it will be seen from Fig. 4 that entrained air downflows are established in pipes 1, 6 and 14 as expected. However, the entrained airflow in pipe 19 is into the network from the sewer. Initially, as there is only a trickle water flow in pipe 19, the entrained airflow in pipe 19 due to the . discharges already being carried by pipes 1, 6 and 14, is reversed, . up the stack, and contributes to the entrained airflow demand in pipes 1, 6 and 14. The AAV on pipe 12 also contributes but initially this is a small proportion of the required airflow and the AAV flutters in response to local pressure conditions. airflows during appliance discharge.Following the . discharge to stack 4 that establishes a water downflow in pipe 19 from 2本科畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文文獻(xiàn)、資料題目：Sealed building drainage and vent systems文獻(xiàn)、資料來(lái)源：國(guó)道數(shù)據(jù)庫(kù)文獻(xiàn)、資料發(fā)表（出版）日期：院 （部）： 市政與環(huán)境工程學(xué)院專 業(yè)： 給水排水工程班 級(jí)： 姓 名： 學(xué) 號(hào)：指導(dǎo)教師： 翻譯日期： 山東建筑大學(xué)畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文外文文獻(xiàn)：Sealed building drainage and vent systems—an application of active air pressure transient control and suppressionAbstractThe introduction of sealed building drainage and vent systems is considered a viable proposition for plex buildings due to the use of active pressure transient control and suppression in the form of air admittance valves and positive air pressure attenuators coupled with the interconnection of the network39。s onwards, the reversed airflow initially established diminishes due to the traction applied by the falling water film in that pipe. However, the suction pressures developed in the other three stacks still results in a continuing but reduced reversed airflow in pipe 19. As the water downflow in pipe 19 reaches its maximum value from 3s 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(guò)成對(duì)的吸氣閥和正壓衰減器與管網(wǎng)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(rèn)為是一個(gè)可行的提議。這種方法盡管既被證明了，也是傳統(tǒng)的，但也有其內(nèi)在弱點(diǎn)，如通氣管末端較遠(yuǎn)[7]，導(dǎo)致了綜合樓緩解反應(yīng)到達(dá)較遲和敞開(kāi)屋面立管末端內(nèi)在的多樣性。在過(guò)去20年里，吸氣閥（AAVs）的發(fā)展給設(shè)計(jì)師提供了一種緩解瞬時(shí)負(fù)壓的方法，如在隨機(jī)的潔具排水過(guò)程中，吸氣閥有助于系統(tǒng)中水力條件的恢復(fù)。這種模擬實(shí)驗(yàn)在水封不被破壞，系統(tǒng)壓力得以維持的條件下，能夠辨認(rèn)活性氣壓控制設(shè)備的作用。s. Fig. 5 illustrates the air pressure profile from the stack base in both stacks 1 and 4 at Trap retention。s and 300s, the increasing and decreasing phases of the transient propagation being presented sequentially. The traces illustrate the propagation of the positive transient up the stack as well as the pressure oscillations derived from the reflection of the transient at the stack termination at the AAV/PAPA junction at the upper end of pipe 11..(a) Sequential air pressure profiles in stack 1 during initial phase of stack base surcharge. (b) Sequential air pressure profiles in stack 1 during final phase of stack base surcharge. 8. Sewer imposed transientsTable 2 illustrates the imposition of a series of sequential sewer transients at the base of each stack. Fig. 8 demonstrates a pattern that indicates the operation of both the PAPA installed on pipe 13 and the selfventing provided by stack interconnection. airflows as a result of sewer imposed pressure transients.As the positive pressure is imposed at the base of pipe 1 at 12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(guó)定義通過(guò)Darcy Δh=4fLu2/2Dg g——重力加速度, m/s2 K——損失系數(shù)L——管長(zhǎng), m p——壓力, N/m2 t——時(shí)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(shí)間間隔, s ρ——密度, kg/m3目錄命名原則――瞬時(shí)氣壓的控制和抑制。正壓衰減器[10]被開(kāi)發(fā)用來(lái)吸收瞬時(shí)正壓產(chǎn)生的氣流，這種衰減器完成了必要的設(shè)備供應(yīng)，為劇烈的瞬時(shí)氣壓