Design and compression efficiency analysis of a Mach 0∼4 variable TBCC intake

This paper aims to develop an intake with balanced wide-speed-range performance for TBCC. A type of simple adjusting mechanism for intake compression section is proposed, which enables contraction ratio (CR) largely varying within 3.60∼7.14 (the change ratio reaches to 98.3%). The CR distribution locates close to ‘Isentropic Limit’ to obtain both good compression ratio and start ability within Mach 0∼4. The numerical methods are validated depending on comparison with supersonic wind tunnel test results. The upward migration effects of terminal shock (TS) at ramjet and transition modes are detail analyzed. Empirical curves are established based on intensive simulation cases to explain the change of intake compression ability under varying inflow speeds and backpressure values. Furthermore, a compression index (CI) is newly defined based on Waltrup's and Tani's previous research foundation, which achieves a more precise evaluation for intake efficiency. The CI theory also manages comparison between different intakes with any working condition and any configuration. In contrast to most recent variable TBCC intakes and typical high-speed intakes, the current variable TBCC intake is proved to be in a high level of CI at design (CI= 0.82) condition and at the whole speed range (CI= 0.75∼0.82). •A novel variable TBCC intake with 1 degree of freedom is designed, which achieves large-scale change in contraction ratio (3.60∼7.14).•A quantitative evaluating method for intake efficiency is developed, which manages comparison despite of speed magnitudes and intake types.•Response hysteresis effect is utilized to obtain a balanced performance of wide-range intake start and high compression efficiency.