ɐ fˈoːɹθ, ʌnjˈuːʒuːəl, tˈaɪp ɪz ðə fɹˈiːpˈɪstən ɡˈæs dʒˈɛnɚɹˌeɪɾɚ, wˌɪtʃ kəmbˈaɪnz ðə fˈʌŋkʃənz ʌv kəmpɹˈɛsɚ ænd kəmbˈʌstʃən tʃˈeɪmbɚɹ ɪn wˈʌn jˈuːnɪt.
A fourth, unusual, type is the free-piston gas generator, which combines the functions of compressor and combustion chamber in one unit.