Raw and processed data for a loudspeaker-coupled thermoacoustic Stirling engine above the Hopf threshold

This dataset supports a study of a thermoacoustic Stirling engine loaded with an audio loudspeaker and operated above its Hopf threshold, where the loudspeaker acts as a linear alternator and the engine sustains a self-excited acoustic limit cycle. It provides the raw measurements, the processed signals, the apparatus specifications and calibration, and the identified model parameters, so that the saturated branch and its identification can be reproduced and independently checked. Data were gathered on a single rig at six supercritical conditions, set by the nominal hot-to-cold temperature difference from 365 K to 415 K in 10 K steps. At each condition the engine was driven from rest to a saturated limit cycle while four channels were sampled synchronously at 3276.8 Hz: the waveguide pressure at x = 0.44 m, the loudspeaker front-end pressure P+ at the front flange (x = -L_d = -1.890 m), the cone velocity from a laser Doppler vibrometer, and the terminal voltage. Both pressures used JTEKT PMS-5M-2 transducers (nominal sensitivity 7.49 Pa/mV); each transducer's own factory calibration was applied, so the records are stored directly in Pa. The heat-exchanger temperature histories are retained as the prescribed thermal forcing. The package has six documented folders (specifications, operating conditions, calibration and identified parameters, computed results, an onset reference, and the raw HDF5 records), with a README and cross-check log. The raw records carry a fundamental near 26 Hz. The fundamental envelope is recovered by demodulating about a fixed carrier and resampling to a 0.5 s grid, and the time axis is reconstructed from the sampling-rate attribute. Every figure and table of the related article reproduces from the processed CSV files without the raw records. Related article: S.-H. Hsu and C.-H. Lai, Adjoint identification of a loudspeaker-coupled thermoacoustic Stirling engine above the Hopf threshold (under review), with an accompanying Data in Brief article.