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  本文關鍵詞：不同激勵方式對矩形聲場均勻性的影響　出處：《陜西師范大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 正弦信號 合成信號 諧振帶寬 聲場分布 均勻性

【摘要】：大功率超聲設備一般由超聲波發(fā)生器和超聲波換能器兩部分組成。由信號發(fā)生器產生特定頻率的信號激勵換能系統(tǒng),使系統(tǒng)保持在諧振狀態(tài)下工作。在大功率超聲的各類應用中,聲場的分布情況對應用效果的影響起著重要的作用。本文根據聲波疊加原理和波動聲學理論,利用聲波的不相干性和擴散聲場的特點設計出一種頻率連續(xù)變化的窄帶多頻合成信號激勵相應換能系統(tǒng)工作,并結合實驗研究對比分析了不同激勵方式下矩形聲場的分布情況。具體工作包括以下幾個方面：1根據波動聲學理論和聲波疊加原理分析了單頻聲波和多頻不相干聲波在矩形空間的分布情況。研究表明：多頻下的聲場是由單頻大量的簡正振動方式疊加與多頻不相干聲波疊加而成的,且頻率越高,簡正振動方式越多,聲場越均勻。2根據白噪聲信號在固定頻帶寬度時頻譜連續(xù)且均勻的特點,設計出經帶通濾波器濾波之后的白噪聲信號作為多振子換能系統(tǒng)的激勵信號,可以滿足系統(tǒng)保持長期穩(wěn)定工作的需求。本文采用Matlab軟件編程生成信號,并經過第三方軟件UltraWave將信號引入函數發(fā)生器,實現信號的分析。結果發(fā)現：白噪聲信號經濾波之后幅值很低,不能驅動相應換能系統(tǒng)工作。進一步提出并確定等幅正弦疊加的多頻合成信號作為系統(tǒng)的激勵信號。3將矩形超聲換能系統(tǒng)的諧振特性分別在小信號模式和大信號模式下進行測量與分析,以便對合成信號的帶寬進行準確設計。研究發(fā)現：兩種激勵方式下系統(tǒng)的諧振特性是不同的,主要表現在：兩種方式下系統(tǒng)的諧振帶寬均隨著頻率的增加而加寬；系統(tǒng)在大信號激勵方式下諧振頻率fs和諧振帶寬△fs整體偏大。根據大功率超聲換能系統(tǒng)實際工作需要,確定依據大信號激勵方式下的諧振頻率和諧振帶寬作為合成信號參數設計的標準。4基于大信號方式下測得的諧振帶寬△fs,對信號分別在帶寬△f△fs、Δf=Δfs、ΔfΔfs進行合成信號設計,結合系統(tǒng)工作時的電參數和染色法聲場分布與正弦信號激勵下的情況進行對比分析。結果表明：合成信號帶寬范圍設計在△f△fs時,系統(tǒng)整體的性能較好,且在高頻系統(tǒng)中更為穩(wěn)定；電參數下的有功功率和電效率相比正弦信號呈現出稍微降低的趨勢,且在低頻信號表現更為明顯,但聲場的均勻性都得到一定的改善。而在△f≥△fs,不論是電參數還是聲場均勻性方面,效果均不如△f△fs信號的情況。綜合分析指出合成信號的最佳帶寬選取在諧振帶寬一般時,即△f=△fs/2,系統(tǒng)的各方面性能最好。5測試信號分別選取正弦信號和最佳帶寬的合成信號激勵矩形換能系統(tǒng),并通過銅版紙染色法和水聽器聲壓測量法對矩形槽內的聲場進行了測量與分析。實驗結果表明：在聲場均勻性方面,高頻聲場優(yōu)于低頻聲場,合成信號優(yōu)于正弦信號。聲壓測點的平均效果表現為合成信號聲壓相對值大于對應位點正弦信號聲壓相對值,間接地說明了合成信號的電聲轉化效率要高于正弦信號。
[Abstract]:The high power ultrasonic equipment is usually composed of two parts: ultrasonic generator and ultrasonic transducer. A signal generator is generated by a signal generator to stimulate the energy exchange system to keep the system working in a resonant state. In the various applications of high power ultrasound, the distribution of sound field plays an important role in the effect of the application. According to the principle of superposition and acoustic wave acoustics theory, the coherence and diffuse field acoustic features designed to change a narrow-band continuous frequency multi frequency synthesis signal excitation corresponding transducer system, and combined with the experimental study on comparative analysis of the distribution of rectangular field under different seismic excitations. The specific work includes the following aspects: 1. According to the wave acoustic theory and the superposition principle, the distribution of single frequency and multi frequency incoherent sound waves in rectangular space is analyzed. The research shows that the sound field at multiple frequencies is superimposed by a large number of single mode normal mode superposition and multiple frequency uncorrelated sound waves, and the higher the frequency, the more the normal mode of vibration is, the more uniform the sound field is. 2, according to the continuous and uniform spectrum of white noise signal in fixed band width, we design a white noise signal filtered by bandpass filter as the excitation signal of multi oscillator energy conversion system, which can meet the needs of long-term stable work of the system. In this paper, the signal is generated by Matlab software programming, and the signal is analyzed by introducing the signal into a function generator through third party software UltraWave. The results show that the amplitude of the white noise signal is very low after filtering, and it can not drive the work of the corresponding energy exchange system. The multi frequency synthetic signal with equal amplitude sinusoidal superposition is further proposed and determined as the excitation signal of the system. 3, the resonant characteristics of the rectangular ultrasonic energy conversion system are measured and analyzed under small signal mode and large signal mode respectively, so as to accurately design the bandwidth of the synthetic signal. The study found that: the resonant characteristics of two kinds of incentive modes of system is different, mainly in two ways: the resonant bandwidth system was widened with the increase of frequency; large signal excitation system in the resonant frequency of FS resonant FS overall larger bandwidth. According to the actual working needs of the high-power ultrasonic energy conversion system, we must determine the resonance frequency and the vibration bandwidth according to the large signal excitation mode as the design criteria of the synthetic signal parameters. 4 based on the mode of large signal measurement of the resonant bandwidth FS, the signal which are synthesized signal design in bandwidth delta f delta FS, Delta f=, delta FS, delta f delta FS, combined with the electrical parameters and dyeing method and field distribution of sine signal excitation system is working under the condition of comparative analysis. The results show that the synthetic signal bandwidth design in delta f delta FS, the overall system performance is better, and in the high frequency system is more stable; electrical parameters of the active power and power efficiency compared to the sinusoidal signal shows a slightly decreasing trend, and the performance in the low frequency signal is more obvious, but the uniformity of sound field to get some improvement. In the delta f delta FS, whether electric parameters or acoustic field uniformity, the effects are not the delta f delta FS signal. Comprehensive analysis points out that the optimum synthetic bandwidth signal selection in resonant bandwidth, namely Delta f= Delta fs/2, the best performance of the system. 5, the test signal selects the sinusoidal signal and the best bandwidth synthetic signal excitation rectangle energy conversion system respectively, and the sound field in the rectangular groove is measured and analyzed by the method of the coated paper stain and the hydrophone's sound pressure measurement. The experimental results show that the high frequency sound field is superior to the low frequency sound field in the field uniformity, and the synthetic signal is better than the sinusoidal signal. The average effect of sound pressure measurement points is that the relative value of synthetic signal pressure is greater than that of corresponding location sinusoidal signal, which indirectly indicates that the efficiency of synthetic signal's electroacoustic conversion is higher than that of sinusoidal signal.
【學位授予單位】：陜西師范大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB55

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