| Inertance tubes are widely used to adjust the phase angle between the mass flow rate and pressure wave at the cold end of pulse tube cryocoolers for the purpose of improving their performance and optimizing their efficiency. The phase shift mechanism is very sensitive to the dimensions of the inertance tube, such as diameter and length. However, due to variations in fabrication or assembly, it is often uncertain whether the installed fixed dimensions inertance tubes produce the desired phase shift. Therefore, the variable inertance tubes allowing continuous adjustments to their geometry during operation has been constructed and mounted on a linear compressor to explore the phase shift behavior of the inertance tube.;The first chapter summarizes the background and gives a broad review of inertance tubes using in the pulse tube cryocooler. The second chapter describes the theoretical simulations of the linear adjustable inertance tubes. Details regarding the adjustable length inertance tube are provided along with a description of the mass flow meter and other components utilized in the verification test, including a LabVIEW-based lock-in amplifier. The Distributed Component Model (DCM) is discussed to help the design of the inertance tubes. Based on the distributed component model, the design method of the adjustable inertance tube is generated by using Matlab internal functions. A figure of merit for the different adjustable inertance tubes is also discussed in this thesis.;The third chapter provides the design methods of the conical and threaded adjustable diameter inertance tube. Also, details about how to fabricate the prototype of the conical adjustable diameter inertance tube will be described in this chapter. The fourth section describes the modified Distributed Component Model, regarding the leakage and entrance effects from the cylindrical threaded adjustable inertance tube. The calculated model results match the experimental data at different working conditions. The detailed adjustable inertance tube experimental operation procedure and test results are illustrated in this chapter.;The fifth chapter summarizes the entire adjustable inertance tube model and experimental results. |
