توسعه ی مدل برای فرایند شروع و میرایی موتور گرماصوتی موج ایستا

این مقاله یک روش مدل‌سازی موتور گرماصوتی موج ایستا برای بررسی شرایط سیستم در حالت گذرا را ارائه می‌کند. تمرکز این روش بر دقیق‌سازی پیش‌بینی‌ها و ایجاد شناخت بهتر درباره‌ی شرایط عملکردی این دستگاه‌هاست. ایده‌یی که پایه‌ی اصلی این کار را تشکیل می‌دهد تلفیق روش حل عددی حالت گذرا و همترایی مدار الکتریکی موتور گرماصوتی موج ایستاست. با فرض هر جزء موتور گرماصوتی به‌عنوان یک المان فشرده‌ی همترایی مدار الکتریکی یک موتور گرماصوتی موج ایستا صورت می‌پذیرد. نتیجه‌ی حاصل از ترکیب روش حل عددی وابسته به زمان و همترایی مدار الکتریکی، یک کد برنامه‌نویسی است که امکان تعیین شرایط شروع، پایداری و میرایی نوسانات خودبه‌خودی در یک موتور گرماصوتی موج ایستا را فراهم می‌کند. با استفاده از این روش، لحظه‌ی شروع نوسانات خودبه‌خودی در سیستم 13٫1 ثانیه محاسبه شد.

M‌O‌D‌E‌L D‌E‌V‌E‌L‌O‌P‌M‌E‌N‌T F‌O‌R S‌T‌A‌R‌T‌U‌P A‌N‌D D‌A‌M‌P‌I‌N‌G O‌F A S‌T‌A‌N‌D‌I‌N‌G W‌A‌V‌E T‌H‌E‌R‌M‌OA‌C‌O‌U‌S‌T‌I‌C E‌N‌G‌I‌N‌E

This paper presents a numerical method to evaluate the system conditions in transient mode for a standing wave thermoacoustic engine (STAE). This method focuses on increasing the accuracy of predictions and creating a better eyesight of the operating conditions of these devices. Combining the numerical solution of transient mode with the electrical circuit analogy of standing wave TAE, is the main idea of this work. Electrical circuit analogy of STAE is done by assuming each component of a STAE as a lumped element. The result of Combining the timedependent numerical solution and the electrical circuit analogy is a code, which determines the condition of startup, steady periodic, and damping regime of the spontaneous oscillations in the STAE. Accordingly, a nonlinear temperature distribution is obtained along the hot core. The developed numerical approach is in line with the experimental results of a STAE. Based on this method, the temperature variations along the stack and the impact of stack material on startup time and onset temperature are numerically investigated. Additionally, the onset temperature profiles are calculated and presented comparatively for the numerical and experimental results. The startup time of spontaneous oscillations is calculated for the standing wave system. Consequently, the best geometry that quickly reaches the sustained oscillations can be selected using this model. Examining the temperature profile during the startup and damping process highlights a temperature difference between these two processes. Observations show that using a material with lower thermal conductivity in the stack section can reduce the onsetdamping temperature difference. Also, with the help of this method the startup moment of spontaneous oscillations was calculated as second in the system. The data obtained from the experimental tests and the temperature profiles resulting from the numerical solution method, showed a good agreement with each other for the onset and damping process in the system. The novel approach described here shows potential in capturing the onsetdamping behavior of thermoacoustic systems efficiently.