型線結(jié)構(gòu)對渦旋膨脹機性能影響的研究
發(fā)布時間：2018-07-20 16:24
【摘要】：利用有機朗肯循環(huán)回收發(fā)動機廢氣余熱,是實現(xiàn)節(jié)能減排和環(huán)境保護(hù)的有效技術(shù)途徑之一。本文對有機朗肯循環(huán)發(fā)動機廢氣余熱回收系統(tǒng)的關(guān)鍵部件渦旋膨脹機進(jìn)行了相關(guān)模擬和研究,研究內(nèi)容如下。首先,對渦旋型線嚙合理論進(jìn)行了介紹,明確了渦旋型線嚙合的基本條件。構(gòu)造出線段漸開線、正四邊形漸開線和圓漸開線三種等壁厚漸開線類渦旋型線并對其結(jié)構(gòu)參數(shù)進(jìn)行了計算,分析了三種型線對渦旋膨脹機結(jié)構(gòu)參數(shù)和工作性能的影響,得出如下結(jié)論:在小型輕量化的前提下,圓漸開線優(yōu)于另外兩種型線。其次,針對本課題組有機朗肯循環(huán)系統(tǒng)中的渦旋膨脹機,在保證其占用空間不變的前提下,建立了高次曲線組合型線、圓弧組合型線及變徑基圓漸開線渦旋型線三種變壁厚渦旋膨脹機的幾何模型,為之后的膨脹機流場仿真及性能的分析奠定了基礎(chǔ)。再次,以R123為工質(zhì),采用RNG k??湍流模型、PISO流場求解算法及動網(wǎng)格技術(shù)對渦旋膨脹機內(nèi)部流場進(jìn)行了三維非定常數(shù)值模擬,得到了各曲軸轉(zhuǎn)角下渦旋膨脹機內(nèi)部壓力、速度及溫度的分布情況及變化規(guī)律,并對膨脹機排氣過程進(jìn)行了分析。由于渦旋膨脹機的工作過程是非穩(wěn)態(tài)過程,其質(zhì)量流量、輸出扭矩、功率等參數(shù)隨運行時間不斷變化。文章最后針對建立的三種變壁厚渦旋齒膨脹機模型,利用Fluent進(jìn)行膨脹機工作過程的非穩(wěn)態(tài)數(shù)值模擬,得出型線類型及運行工況對渦旋膨脹機性能的影響規(guī)律:(1)針對本課題組所用圓漸開線渦旋膨脹機,當(dāng)占用空間及運行工況相同時,變徑基圓漸開線與圓漸開線渦旋膨脹機相比,扭矩增大0.03Nm,功率提高5.33W,效率提升3.3%。組合型線與圓漸開線渦旋膨脹機相比,扭矩、功率及效率均有所下降。(2)對于高次曲線組合型線渦旋膨脹機,當(dāng)進(jìn)出口邊界條件相同時,輸出扭矩隨轉(zhuǎn)速的增大而降低,輸出功率及效率隨轉(zhuǎn)速的增大先升高隨后降低;當(dāng)膨脹機進(jìn)口過熱度、轉(zhuǎn)速及出口壓力一定時,輸出扭矩、功率及效率隨進(jìn)口壓力的增加而增加。
[Abstract]:The recovery of engine exhaust heat by organic Rankine cycle is one of the effective technical ways to realize energy saving and environmental protection. In this paper, the vortex expander, a key component of the exhaust gas waste heat recovery system of organic Rankine cycle engine, is simulated and studied. The research contents are as follows. Firstly, the theory of vortex line meshing is introduced, and the basic conditions of vortex line meshing are defined. The involute, quadrilateral involute and circular involute are constructed, and the structure parameters of involute are calculated. The influence of the three kinds of involute on the structure parameters and working performance of the scroll expander is analyzed. The conclusion is as follows: the circular involute is superior to the other two shapes on the premise of small weight. Secondly, in view of the vortex expander in the organic Rankine circulatory system of our group, on the premise of keeping its occupied space unchanged, the combination curve of high order curve is established. The geometric models of three kinds of variable wall thickness vortex expander with combined arc profile and variable diameter base circle involute vortex line have laid a foundation for the simulation of flow field and the analysis of the performance of the expander. Thirdly, using R123 as working medium, using RNG KG? The turbulent model PISO flow field solution algorithm and dynamic grid technique are used to simulate the internal flow field of the vortex expander. The distribution and variation of the internal pressure, velocity and temperature of the vortex expander under the crankshaft rotation angle are obtained. The exhaust process of the expander is analyzed. Since the working process of the vortex expander is unsteady, the mass flow, output torque and power of the vortex expander vary with the running time. In the end of this paper, the unsteady numerical simulation of the expander's working process is carried out by using fluent, aiming at the three kinds of models of variable wall thickness vortex tooth expander. The effects of profile type and operating conditions on the performance of scroll expander are obtained. (1) for the circular involute scroll expander used in our group, when the space is occupied and the operating conditions are the same, the involute of variable diameter base circle is compared with the circular involute vortex expander. Torque increased by 0.03Nm, power increased by 5.33W, efficiency increased by 3.3Nm. Compared with the circular involute vortex expander, the torque, power and efficiency of the combined involute vortex expander are decreased. (2) for the high order curve combined type vortex expander, when the inlet and outlet boundary conditions are the same, the output torque decreases with the increase of the rotational speed. The output power and efficiency first increase and then decrease with the increase of rotational speed, and when the inlet superheat, speed and outlet pressure of the expander are fixed, the output torque, power and efficiency increase with the increase of inlet pressure.
【學(xué)位授予單位】：北京理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X734.2;U464
本文編號：2134089
[Abstract]:The recovery of engine exhaust heat by organic Rankine cycle is one of the effective technical ways to realize energy saving and environmental protection. In this paper, the vortex expander, a key component of the exhaust gas waste heat recovery system of organic Rankine cycle engine, is simulated and studied. The research contents are as follows. Firstly, the theory of vortex line meshing is introduced, and the basic conditions of vortex line meshing are defined. The involute, quadrilateral involute and circular involute are constructed, and the structure parameters of involute are calculated. The influence of the three kinds of involute on the structure parameters and working performance of the scroll expander is analyzed. The conclusion is as follows: the circular involute is superior to the other two shapes on the premise of small weight. Secondly, in view of the vortex expander in the organic Rankine circulatory system of our group, on the premise of keeping its occupied space unchanged, the combination curve of high order curve is established. The geometric models of three kinds of variable wall thickness vortex expander with combined arc profile and variable diameter base circle involute vortex line have laid a foundation for the simulation of flow field and the analysis of the performance of the expander. Thirdly, using R123 as working medium, using RNG KG? The turbulent model PISO flow field solution algorithm and dynamic grid technique are used to simulate the internal flow field of the vortex expander. The distribution and variation of the internal pressure, velocity and temperature of the vortex expander under the crankshaft rotation angle are obtained. The exhaust process of the expander is analyzed. Since the working process of the vortex expander is unsteady, the mass flow, output torque and power of the vortex expander vary with the running time. In the end of this paper, the unsteady numerical simulation of the expander's working process is carried out by using fluent, aiming at the three kinds of models of variable wall thickness vortex tooth expander. The effects of profile type and operating conditions on the performance of scroll expander are obtained. (1) for the circular involute scroll expander used in our group, when the space is occupied and the operating conditions are the same, the involute of variable diameter base circle is compared with the circular involute vortex expander. Torque increased by 0.03Nm, power increased by 5.33W, efficiency increased by 3.3Nm. Compared with the circular involute vortex expander, the torque, power and efficiency of the combined involute vortex expander are decreased. (2) for the high order curve combined type vortex expander, when the inlet and outlet boundary conditions are the same, the output torque decreases with the increase of the rotational speed. The output power and efficiency first increase and then decrease with the increase of rotational speed, and when the inlet superheat, speed and outlet pressure of the expander are fixed, the output torque, power and efficiency increase with the increase of inlet pressure.
【學(xué)位授予單位】：北京理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X734.2;U464
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