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摘要 在眾多的工業(yè)現(xiàn)場中,兩相(氣/液,氣/固和液/固)流體的測量是一個(gè)長期未能得到很好解決的難題�；ハ嚓P(guān)技術(shù)和超聲波傳感器的出現(xiàn)使兩相流的非接觸式測量成為可能。因此,超聲波互相關(guān)流速計(jì)的研究是一項(xiàng)具有重大意義的課題。 本文提出了一種采用互相關(guān)技術(shù)實(shí)現(xiàn)氣/液、液/固兩相流流速及流量非接觸式測量的方案。該方案的核心器件為fpga芯片ep1k50qc208-3，利用fpga數(shù)字硬件電路運(yùn)算的快速性和可開發(fā)性構(gòu)成流速計(jì)，勿需其它處理器單元。a/d采樣控制、相關(guān)運(yùn)算、峰值搜索和流速及流量計(jì)算均由fpga完成。由于所有運(yùn)算都由數(shù)字硬件電路完成，所以具有運(yùn)算速度快、實(shí)時(shí)性強(qiáng)、可靠性高的特點(diǎn)。 由fpga實(shí)現(xiàn)的功能主要有以下幾部分：外圍電路控制器，互相關(guān)器和通訊接口控制器。核心部分是互相關(guān)器，所有的功能模塊均由vhdl語言開發(fā)。并且為滿足互相關(guān)運(yùn)算的要求，在fpga內(nèi)部還設(shè)計(jì)了兩個(gè)ram作為上、下游流動(dòng)噪聲信號(hào)的緩存。該實(shí)時(shí)測量系統(tǒng)的外圍電路包括超聲波傳感器、發(fā)射器振蕩電路、接收器信號(hào)處理電路和a/d芯片。而外圍電路控制器的主要作用則是控制a/d芯片采 ……（快文網(wǎng)http://hoachina.com省略825字，正式會(huì)員可完整閱讀）…… this paper introduces a non-contact measurement scheme using cross-correlation method to measure flow velocity and flux of gas/liquid and liquid/solide two-phase flow. the core device is a fpga chip, ep1k50qc208-3, to take advantage of fpga’s fast computing and programmable without other processors. a/d sample controlling, cross-correlation computing, peak value searching, and flow velocity and flux calculating are all achieved through the fpga chip. because all operations are executed by digital hardware circuit, the instrument has many merits, such as fast computation, real-time operation and high accuracy. the functions achieved by the fpga consist of the cross-correlation and peripheral circuit and communication port control. the core unit was a cross-correlator and all modules were developed in vhdl. to meet the demands of data processing, two rams were designed as flowing noise signal storage in the fpga. ultrasonic transducers, oscillatory source circuit, receiving signal disposal circuit, and an a/d chip formed the peripheral circuit of the real-time measurement system. the function of the peripheral circuit controller was to manipulate a/d sampling and to buffer data. transmitted ultrasonic signal is modulated by solid particles in the flow and then received by the ultrasonic receivers. the signal is amplified and filtered by the disposal circuit, then be sampled by the a/d chip and be buffered into the ram in fpga. according to upstream and ……（未完，全文共47498字，當(dāng)前只顯示2144字，請(qǐng)閱讀下面提示信息。收藏索海東大論文） 上一篇：轉(zhuǎn)變干部作風(fēng)演講稿——為民便民利民為我們工作的出發(fā)點(diǎn) 下一篇：社區(qū)文明創(chuàng)建實(shí)施方案 相關(guān)欄目：文教論文 綜合論文 |