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首頁> 外文學(xué)位 >Application of low-dimensional techniques for closed-loop control of turbulent flows.
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Application of low-dimensional techniques for closed-loop control of turbulent flows.

機譯：低維技術(shù)在湍流閉環(huán)控制中的應(yīng)用。

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摘要

The groundwork for an advanced closed-loop control of separated shear layer flows is laid out in this document. The experimental testbed for the present investigation is the turbulent flow over a NACA-4412 model airfoil tested in the Syracuse University subsonic wind tunnel at Re=135,000. The specified control objective is to delay separation - or stall - by constantly keeping the flow attached to the surface of the wing. The proper orthogonal decomposition (POD) is shown to he a valuable tool to provide a low-dimensional estimate of the flow state and the first POD expansion coefficient is proposed to he used as the control variable. Other reduced-order techniques such as the modified linear and quadratic stochastic measurement methods (mLSM, mQSM) are applied to reduce the complexity of the flow field and their ability to accurately estimate the flow state from surface pressure measurements alone is examined. A simple proportional feedback control is successfully implemented in real-time using these tools and flow separation is efficiently delayed by over 3 degrees angle of attack. To further improve the quality of the flow state estimate, the implementation of a Kalman filter is foreseen, in which the knowledge of the flow dynamics is added to the computation of the control variable to correct for the potential measurement errors. To this aim, a reduced-order model (ROM) of the flow is developed using the least-squares method to obtain the coefficients of the POD/Galerkin projection of the Navier-Stokes equations from experimental data. To build the training ensemble needed in this experimental procedure, the spectral mLSM is performed to generate time-resolved series of POD expansion coefficients from which temporal derivatives are computed. This technique, which is applied to independent PIV velocity snapshots and time-resolved surface measurements, is able to retrieve the rational temporal evolution of the flow physics in the entire 2-D measurement area. The quality of the spectral measurements is confirmed by the results from both the linear and quadratic dynamical systems. The preliminary results from the linear ROM strengthens the motivation for future control implementation of a linear Kalman filter in this flow.
機譯：本文檔介紹了對分離的剪切層流進行高級閉環(huán)控制的基礎(chǔ)。用于本研究的實驗性試驗臺是在錫拉丘茲大學(xué)亞音速風(fēng)洞中Re = 135,000處測試的NACA-4412模型機翼上的湍流。規(guī)定的控制目標是通過不斷保持氣流附著在機翼表面上來延遲分離或失速。適當?shù)恼环纸猓≒OD）被顯示為提供低維流動狀態(tài)估計的有價值的工具，并且建議將第一POD膨脹系數(shù)用作控制變量。還應(yīng)用了其他降階技術(shù)，例如改進的線性和二次隨機測量方法（mLSM，mQSM）來降低流場的復(fù)雜性，并檢查了它們僅通過表面壓力測量即可準確估算流態(tài)的能力。使用這些工具可以成功地實時實現(xiàn)簡單的比例反饋控制，并且流分離有效地延遲了超過3度的迎角。為了進一步提高流動狀態(tài)估計的質(zhì)量，可以預(yù)見卡爾曼濾波器的實現(xiàn)，其中將流動動力學(xué)的知識添加到控制變量的計算中以校正潛在的測量誤差。為此，使用最小二乘法開發(fā)了流的降階模型（ROM），以從實驗數(shù)據(jù)中獲得Navier-Stokes方程的POD / Galerkin投影系數(shù)。為了建立此實驗過程中所需的訓(xùn)練合奏，執(zhí)行頻譜mLSM以生成時間分辨的POD擴展系數(shù)序列，并從中計算時間導(dǎo)數(shù)。該技術(shù)適用于獨立的PIV速度快照和時間分辨的表面測量，能夠檢索整個二維測量區(qū)域中流動物理學(xué)的合理時間演變。線性和二次動力學(xué)系統(tǒng)的結(jié)果證實了光譜測量的質(zhì)量。線性ROM的初步結(jié)果加強了在此流程中對線性卡爾曼濾波器進行未來控制的動機。

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  • 作者

    Ausseur, Julie.;

  • 作者單位

    Syracuse University.;

  • 授予單位 Syracuse University.;
  • 學(xué)科 Engineering Aerospace.
  • 學(xué)位 Ph.D.
  • 年度 2007
  • 頁碼 188 p.
  • 總頁數(shù) 188
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 航空、航天技術(shù)的研究與探索;
  • 關(guān)鍵詞

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