Fig.1

Typical two-stage aerospace vehicle

Fig.2

Working envelope of various propulsion systems［6］

Fig.3

SABRE engine

Fig.4

TRRE engine［15］

Fig.5

Schematic diagram of typical rectangular adjustable inlet （operating Mach number 2-5）

Table 1

Adjustment requirements of rectangular adjustable inlet （operating Mach number 2-5）

Fig.6

Comparison between inlets for traditional flight vehicles and aerospace vehicles

Fig.7

Comparison of total pressure recovery coefficient of fixed geometry inlet with that listed in American MIL-E-5008B standard

Fig.8

Different flow structures that may be formed when external compression shock waves impinge on inner surface of cowl near leading edge （NPLS images）［19］

Fig.9

Different separation structures formed by cowl shock waves at different angles of attack［20］

Fig.10

Schlieren images of shock surge phenomenon in isolator［20］

Fig.11

Thrust and drag profile of typical hypersonic aircraft［21］

Fig.12

Three core requirements and key issues in adjustable inlet for aerospace vehicles

Fig.13

Sketch of inlet adjustment by translation

Fig.14

Sketch of inlet adjustment by rotation

Fig.15

Sketch of inlet adjustment by deformation

Fig.16

Shock wave control method based on wall hot bump［22］

Fig.17

Shock system control method of inlet external compression based on wall plasma excitation［23］

Fig.18

Inlet capture flow regulation method based on upper lip energy deposition［24］

Fig.19

Shock system adjustment method based on local mass addition principle［25］

Fig.20

Rectangular adjustable inlet with rotation compression surface［27］

Fig.21

Rectangular adjustable inlet with compression surface rotating synchronously with diffuser inclined plate［28］

Fig.22

Rectangular adjustable inlet with two different sides and two entrances rotating simultaneously with compression surface and diffuser inclined plate［29］

Fig.23

Rectangular adjustable inlet with synchronous adjustment of compression surface， throat， and diffuser wall［30］

Fig.24

Adjustable inlet based on four-link mechanism adopted in FAP［31］

Fig.25

Rectangular adjustable inlet with four-link mechanism and deformable diffuser

Fig.26

Partially planarized three-dimensional inward turning inlet with four-link adjustment device

Fig.27

Axisymmetric adjustable inlet with two-stage translation adjustment of cowl

Table 2

Performance of axisymmetric adjustable inlet under critical condition

Fig.28

Experimental verification of adjustable inlet based on external compression ramp deformation［39］

Fig.29

Schematic diagram of axisymmetric adjustable inlet based on special airbag

Fig.30

Numerical and experimental results of axisymmetric adjustable inlet based on special airbag

Fig.31

Adjustable supersonic inlet with fixed geometry based on plasma discharge control［23］

Table 3

Plasma control effect in off-design state of inlet （Ma=4）［41］

Fig.32

Schematic diagram of adjustable supersonic inlet with fixed geometry based on jet control technology［42］

Fig.33

Schematic diagram of adjustable supersonic inlet with fixed geometry based on new jet control technology

Fig.34

Variable geometry axisymmetric inlet based on local secondary flow circulation［43］

Fig.35

Schematic diagram of working principle of fixed geometry inlet based on magnetic fluid control［44］

Fig.36

Typical restart process of hybrid inlet［46］

Fig.37

Typical flow field structure of hybrid inlet［47］

Fig.38

Typical flow characteristics during buzz of mixed-compression inlet［58］

Fig.39

Schematic diagram of new oscillation mechanism of hybrid supersonic inlet

Fig.40

Schematic diagram of unstart flow structure caused by large ICR

Fig.41

Unstart flow field of large ICR inlet［88］

Table 4

Main parameters of oscillation in unstarted large ICR inlet［88］

Fig.42

Schematic diagram of physical model of self-excited oscillation induced by large ICR inlet［88］

Fig.43

Hysteresis caused by throat adjustment of large ICR adjustable inlet

Fig.44

Flow hysteresis phenomenon induced by variation of entrance Mach number

Fig.45

Flow hysteresis induced by changes in downstream throttling［105］

Fig.46

Flow hysteresis induced by changes in ICR

Fig.47

Classic start/unstart dual solution region

Fig.48

Kantrowitz hypothesis and actual inlet flow field structure during inlet restart［93］

Fig.49

Unstart and restart boundary prediction results［81］

Fig.50

Active flow control method based on jet and energy injection

Fig.51

Comparison of hysteresis loops between uncontrolled and controlled schemes during throat regulation process［88］

Fig.52

Inlet experimental model adopted by Albertson et al.［120］

Fig.53

Time-varying curves of inlet flow of low-speed duct and high-speed duct

Fig.54

Schematic diagram of inlet model studied by NASA［123］

Fig.55

Variation of geometry ICR and unstart and restart boundaries of dual-solution area［125］

Fig. 56

Flow field of high/low speed duct under different back pressure during mode transition of internal combined cycle engine inlet［126］

Fig.57

Comparison of quasi-steady and unsteady numerical simulation results of mode transition process of internal combined cycle engine inlet［127］

Fig.58

Flow field at typical moments during mode transition process of internal combined cycle engine inlet［128］