本文選題：微型擺式發(fā)動機 + 回熱器��； 參考：《南京航空航天大學》2016年碩士論文

【摘要】：為了滿足便攜式電子產品越來越大的用電需求,采用碳氫燃料的微動力發(fā)電裝置因其在能量轉化方面的巨大優(yōu)勢,迅速成為新一代便攜式電源的發(fā)展趨勢。微型擺式發(fā)動機具有便于微型化,能量密度高的特點,是未來便攜式電源的發(fā)展趨勢之一,但由于發(fā)動機尾氣帶走了燃燒產生的大部分熱量,其熱效率低下,為此引入回熱技術對提升發(fā)動機性能十分必要。適用于微型擺式發(fā)動機的回熱器具有冷熱氣流量小,脈沖特性明顯的特點,與常規(guī)回熱器工作流動形式差異明顯。本文為對微型脈沖式回熱器進行試驗研究,設計了微型脈沖式回熱器試驗臺,并對回熱器換熱效率影響因素進行了試驗和數(shù)值模擬研究。本文首先對加裝微型回熱器后的微型擺式發(fā)動機運行困難的問題進行分析,改進發(fā)動機結構,并采用混合動力循環(huán)驅動發(fā)動機正常運行。分析發(fā)動機工作循環(huán),獲得回熱器冷熱氣真實流動情況。模擬回熱器冷熱氣進出口條件,設計試驗臺及試驗測量方案。查閱文獻可知,微型化后發(fā)動機內泄漏對發(fā)動機影響較大。建立發(fā)動機內泄漏數(shù)學模型,對發(fā)動機內泄漏進行分析,并設計試驗臺封嚴手段,研究結果表明:由于尺寸微小化,樣機內泄漏流質量占到樣機內氣體總質量的大部分;通過改變泄漏縫隙尺寸和樣機運行頻率可抑制有效樣機內泄漏;提出了一種新型逆向射流式多級凹槽封嚴技術,通過數(shù)值計算,驗證其封嚴效果較好,可抑制泄漏流量達到12%以上。對回熱器換熱效率的影響因素冷氣單次進氣量和脈沖頻率進行了數(shù)值模擬研究,結果發(fā)現(xiàn):由于冷氣單次進氣量和脈沖頻率變化對回熱器內流場的影響,導致回熱器冷氣對流換熱能力增強,使得回熱器換熱效率雖然由于冷氣需吸收的熱量增加和換熱時間較少的原因出現(xiàn)下降,但下降幅度不大。同時發(fā)現(xiàn)回熱器換熱效率較定常流動時降低,造成這種變化的原因為微型化后,脈沖效應引起的回熱器內沿換熱間壁的軸向導熱引起的。接著對回熱器換熱效率的影響因素進行試驗研究。目前試驗臺目前工作頻率可達25Hz,熱氣溫度可上升至700℃。在試驗臺調試階段發(fā)現(xiàn)脈沖流發(fā)生器內泄漏嚴重,增壓較低,驗證了泄漏問題的嚴重影響,并驗證了運行頻率對泄漏的抑制。采用油脂密封和篦齒封嚴應用于試驗臺,從試驗數(shù)據(jù)來看,油脂密封能夠獲得較好的密封效果,可應用于試驗臺上;篦齒封嚴技術可一定程度上抑制泄漏流,但目前效果不明顯。進行了微型脈沖式回熱器換熱效率試驗,試驗中由于散熱和試驗管路導熱的原因,導致測量得到的換熱效率較低,考慮兩者影響后,試驗換熱效率達到60%左右,通過分析,符合預期效果,且試驗規(guī)律驗證了數(shù)值模擬結果。
[Abstract]:In order to meet the increasing demand of portable electronic products, the new generation of portable power supply is rapidly becoming the development trend of the new generation portable power supply because of its great advantage in energy conversion. Micro pendulum engine is one of the development trends of portable power supply in the future because of its convenience for miniaturization and high energy density. However, because engine exhaust takes away most of the heat produced by combustion, its thermal efficiency is low. Therefore, it is necessary to introduce regenerative technology to improve engine performance. The recuperator suitable for micro pendulum engine has the characteristics of low flow rate of cold and hot air and obvious pulse characteristics, which is different from the working flow form of conventional recuperator. In this paper, in order to study the miniature pulse regenerator, a miniature pulse regenerator test-bed is designed, and the factors affecting the heat transfer efficiency of the regenerator are studied by experiment and numerical simulation. In this paper, the difficulty of the micro pendulum engine with micro regenerator is analyzed, the engine structure is improved, and the hybrid cycle drive engine is used to run normally. The real flow of hot and cold gas in the regenerator is obtained by analyzing the engine working cycle. Simulates the inlet and outlet condition of the regenerator, designs the test bed and the test measurement scheme. It can be seen from the literature that the internal leakage of the engine after miniaturization has a great influence on the engine. The mathematical model of engine internal leakage is established, the internal leakage of engine is analyzed, and the sealing method of test bed is designed. The results show that the mass of leakage flow in the prototype accounts for the majority of the total mass of gas in the prototype because of the miniaturization of the size; The leakage in the prototype can be restrained by changing the leak slot size and the operating frequency of the prototype, and a new type of reverse jet multistage groove sealing technology is proposed. The numerical results show that the sealing effect is good. The leakage rate can be restrained by more than 12%. The factors affecting the heat transfer efficiency of the regenerator are numerically simulated. The results show that the flow field in the regenerator is affected by the variation of the single air intake and the pulse frequency. As a result, the convection heat transfer capacity of the regenerator is enhanced, and the heat transfer efficiency of the regenerator is reduced because of the increase of the heat absorbed by the air conditioner and the decrease of the heat transfer time, but the decrease is not significant. At the same time, it is found that the heat transfer efficiency of the regenerator is lower than that of the steady flow, which is caused by the axial heat conduction of the inner wall of the regenerator caused by the pulse effect after miniaturization. Then the factors affecting the heat transfer efficiency of the regenerator are studied experimentally. At present, the operating frequency of the test bed can reach 25 Hz, and the hot gas temperature can rise to 700 鈩，

本文編號：2013129