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Oblique shock

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82: 25: 149: 998: 987: 141: 976: 1010:. A type of these inlets is wedge-shaped to compress air flow into the combustion chamber while minimizing thermodynamic losses. Early supersonic aircraft jet engine intakes were designed using compression from a single normal shock, but this approach caps the maximum achievable Mach number to roughly 1.6. 200:
can be supersonic (weak shock wave) or subsonic (strong shock wave). Weak solutions are often observed in flow geometries open to atmosphere (such as on the outside of a flight vehicle). Strong solutions may be observed in confined geometries (such as inside a nozzle intake). Strong solutions are
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Oblique shocks are often preferable in engineering applications when compared to normal shocks. This can be attributed to the fact that using one or a combination of oblique shock waves results in more favourable post-shock conditions (smaller increase in entropy, less stagnation pressure loss,
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Many supersonic aircraft wings are designed around a thin diamond shape. Placing a diamond-shaped object at an angle of attack relative to the supersonic flow streamlines will result in two oblique shocks propagating from the front tip over the top and bottom of the wing, with
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required when the flow needs to match the downstream high pressure condition. Discontinuous changes also occur in the pressure, density and temperature, which all rise downstream of the oblique shock wave.
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changes in the thermodynamic properties of a gas occur. While the upstream and downstream flow directions are unchanged across a normal shock, they are different for flow across an oblique shock wave.
1233: 108:, is inclined with respect to the direction of incoming air. It occurs when a supersonic flow encounters a corner that effectively turns the flow into itself and compresses. The upstream 231: 971:{\displaystyle M_{2}={\frac {1}{\sin(\beta -\theta )}}{\sqrt {\frac {1+{\frac {\gamma -1}{2}}M_{1}^{2}\sin ^{2}\!\beta }{\gamma M_{1}^{2}\sin ^{2}\!\beta -{\frac {\gamma -1}{2}}}}}.} 1034:
As the Mach number of the upstream flow becomes increasingly hypersonic, the equations for the pressure, density, and temperature after the oblique shock wave reach a mathematical
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lines. The red line separates the strong and weak solutions. The blue line represents the point when the downstream Mach number becomes sonic. The chart assumes
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For a perfect atmospheric gas approximation using γ = 1.4, the hypersonic limit for the density ratio is 6. However, hypersonic post-shock dissociation of O
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etc.) when compared to utilizing a single normal shock. An example of this technique can be seen in the design of supersonic aircraft engine intakes or
1445: 1014:(which first flew in 1969) used variable geometry wedge-shaped intakes to achieve a maximum speed of Mach 2.2. A similar design was used on the 81: 664:{\displaystyle {\frac {\rho _{2}}{\rho _{1}}}={\frac {(\gamma +1)\ M_{1}^{2}\sin ^{2}\!\beta }{(\gamma -1)M_{1}^{2}\sin ^{2}\!\beta +2}}} 399:, with the larger angle called a strong shock and the smaller called a weak shock. The weak shock is almost always seen experimentally. 1476: 1563: 109: 217:
does not change across the shock, trigonometric relations eventually lead to the θ-β-M equation which shows θ as a function of M
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are uniformly deflected after the shock wave. The most common way to produce an oblique shock wave is to place a wedge into
1356:{\displaystyle {\frac {T_{2}}{T_{1}}}\approx {\frac {2\gamma \ (\gamma -1)}{(\gamma +1)^{2}}}\ M_{1}^{2}\sin ^{2}\!\beta .} 367:
and θ, but this approach is more complicated, the results of which are often contained in tables or calculated through a
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created at the two corners of the diamond closest to the front tip. When correctly designed, this generates lift.
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Supersonic wind tunnel test demonstration (Mach 2.5) with flat plate and wedge creating an oblique shock(Video)
391:. A θ-β-M diagram, common in most compressible flow textbooks, shows a series of curves that will indicate θ 120:. Similar to a normal shock wave, the oblique shock wave consists of a very thin region across which nearly 1227:
into O and N lowers γ, allowing for higher density ratios in nature. The hypersonic temperature ratio is:
1023: 1452: 1133:{\displaystyle {\frac {p_{2}}{p_{1}}}\approx {\frac {2\gamma }{\gamma +1}}\ M_{1}^{2}\sin ^{2}\!\beta } 152:
This chart shows the oblique shock angle, β, as a function of the corner angle, θ, for a few constant M
512:{\displaystyle {\frac {p_{2}}{p_{1}}}=1+{\frac {2\gamma }{\gamma +1}}(M_{1}^{2}\sin ^{2}\!\beta -1)} 402:
The rise in pressure, density, and temperature after an oblique shock can be calculated as follows:
1372: 388: 33: 1597: 129: 50: 1592: 779: 159: 90: 762:{\displaystyle {\frac {T_{2}}{T_{1}}}={\frac {p_{2}}{p_{1}}}{\frac {\rho _{1}}{\rho _{2}}}.} 387:, the oblique shock wave is no longer attached to the corner and is replaced by a detached 1602: 395:
for each Mach number. The θ-β-M relationship will produce two β angles for a given θ and M
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Supersonic flow encounters a wedge and is uniformly deflected forming an oblique shock.
1540: 1521: 1498: 1470: 1209:{\displaystyle {\frac {\rho _{2}}{\rho _{1}}}\approx {\frac {\gamma +1}{\gamma -1}}.} 117: 188:, and corner angle, θ, the oblique shock angle, β, and the downstream Mach number, M 1018:(the F-14D was first delivered in 1994) and achieved a maximum speed of Mach 2.34. 368: 1567: 1382: 16:
Shock wave that is inclined with respect to the incident upstream flow direction
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It is always possible to convert an oblique shock into a normal shock by a
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The Dynamics and Thermodynamics of Compressible Fluid Flow, Volume 1
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It is more intuitive to want to solve for β as a function of M
1038:. The pressure and density ratios can then be expressed as: 1423: 192:, can be calculated. Unlike after a normal shock where M 1236: 1149: 1047: 805: 782: 680: 528: 411: 383:, exists for any upstream Mach number. When θ > θ 234: 162: 379:
Within the θ-β-M equation, a maximum corner angle, θ
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Jr. (January 2001) . 1585: 1475:: CS1 maint: archived copy as title ( 204: 1495:McGraw-Hill Science/Engineering/Math 1416: 981: 18: 13: 1561:NASA oblique shock wave calculator 85:An oblique shock at the nose of a 38:it lacks sufficient corresponding 14: 1614: 1554: 89:aircraft is made visible through 776:is solved for as follows, where 23: 1438: 1410: 1306: 1293: 1288: 1276: 1030:Waves and the hypersonic limit 843: 831: 620: 608: 571: 559: 506: 468: 338: 317: 135: 1: 1403: 215:tangential velocity component 1491:Fundamentals of Aerodynamics 1024:Prandtl-Meyer expansion fans 7: 1535:Shapiro, Ascher H. (1953). 1417:Hall, Nancy (13 May 2021). 1366: 10: 1619: 221:, β and ɣ, where ɣ is the 1373:Bow shock (aerodynamics) 375:Maximum deflection angle 1514:Elements of Gasdynamics 789:{\displaystyle \theta } 169:{\displaystyle \gamma } 130:Galilean transformation 53:more precise citations. 1357: 1210: 1134: 1002: 994: 972: 790: 763: 665: 513: 354: 213:and the fact that the 177: 170: 145: 93: 1419:"Oblique Shock Waves" 1358: 1211: 1135: 1000: 989: 973: 791: 764: 666: 514: 355: 171: 151: 143: 91:Schlieren photography 84: 1234: 1147: 1045: 803: 780: 678: 526: 409: 232: 160: 1335: 1115: 925: 891: 637: 591: 485: 316: 279: 223:Heat capacity ratio 211:continuity equation 1566:2011-07-18 at the 1518:Dover Publications 1353: 1321: 1206: 1130: 1101: 1003: 995: 993:intake ramp system 968: 911: 877: 786: 759: 661: 623: 577: 509: 471: 350: 302: 265: 205:The θ-β-M equation 178: 166: 146: 94: 1546:978-0-471-06691-0 1527:978-0-486-41963-3 1504:978-0-07-237335-6 1320: 1316: 1275: 1259: 1201: 1172: 1100: 1096: 1070: 1008:supersonic inlets 982:Wave applications 963: 962: 959: 875: 847: 754: 730: 703: 659: 576: 551: 466: 434: 348: 261: 118:compressible flow 79: 78: 71: 1610: 1550: 1539:. Ronald Press. 1531: 1508: 1493:(3rd ed.). 1481: 1480: 1474: 1466: 1464: 1463: 1457: 1451:. 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Retrieved 1422: 1412: 1388:Moving shock 1378:Gas dynamics 1218: 1033: 1020: 1004: 771: 401: 378: 362: 208: 180:For a given 179: 127: 106:normal shock 97: 95: 65: 56: 37: 1603:Shock waves 1572:Java applet 1393:Shock polar 1016:F-14 Tomcat 182:Mach number 136:Wave theory 110:streamlines 51:introducing 1587:Categories 1462:2013-01-01 1404:References 1398:Shock wave 209:Using the 114:supersonic 102:shock wave 100:wave is a 34:references 1348:β 1297:γ 1283:− 1280:γ 1271:γ 1262:≈ 1195:− 1192:γ 1181:γ 1175:≈ 1164:ρ 1154:ρ 1128:β 1087:γ 1082:γ 1073:≈ 950:− 947:γ 941:− 938:β 909:γ 904:β 866:− 863:γ 841:θ 838:− 835:β 829:⁡ 784:θ 746:ρ 736:ρ 650:β 615:− 612:γ 604:β 563:γ 543:ρ 533:ρ 501:− 498:β 457:γ 452:γ 389:bow shock 336:β 330:⁡ 321:γ 295:− 292:β 257:β 254:⁡ 242:θ 239:⁡ 164:γ 1564:Archived 1471:cite web 1367:See also 1012:Concorde 991:Concorde 47:improve 1543:  1524:  1501:  1430:9 June 1319:  1274:  1099:  575:  260:  36:, but 1456:(PDF) 1449:(PDF) 1223:and N 1036:limit 1541:ISBN 1522:ISBN 1499:ISBN 1477:link 1432:2024 1424:NASA 87:T-38 1338:sin 1118:sin 928:sin 894:sin 826:sin 640:sin 594:sin 488:sin 393:MAX 385:MAX 381:MAX 327:cos 282:sin 251:cot 236:tan 184:, M 96:An 1589:: 1520:. 1516:. 1497:. 1473:}} 1469:{{ 1421:. 371:. 225:. 132:. 116:, 1574:) 1570:( 1549:. 1530:. 1507:. 1479:) 1465:. 1434:. 1351:. 1342:2 1332:2 1327:1 1323:M 1311:2 1307:) 1303:1 1300:+ 1294:( 1289:) 1286:1 1277:( 1268:2 1255:1 1251:T 1245:2 1241:T 1225:2 1221:2 1204:. 1198:1 1187:1 1184:+ 1168:1 1158:2 1122:2 1112:2 1107:1 1103:M 1093:1 1090:+ 1079:2 1066:1 1062:p 1056:2 1052:p 966:. 957:2 953:1 932:2 922:2 917:1 913:M 898:2 888:2 883:1 879:M 873:2 869:1 857:+ 854:1 844:) 832:( 822:1 817:= 812:2 808:M 774:2 772:M 757:. 750:2 740:1 726:1 722:p 716:2 712:p 706:= 699:1 695:T 689:2 685:T 656:2 653:+ 644:2 634:2 629:1 625:M 621:) 618:1 609:( 598:2 588:2 583:1 579:M 572:) 569:1 566:+ 560:( 554:= 547:1 537:2 507:) 504:1 492:2 482:2 477:1 473:M 469:( 463:1 460:+ 449:2 443:+ 440:1 437:= 430:1 426:p 420:2 416:p 397:1 365:1 345:2 342:+ 339:) 333:2 324:+ 318:( 313:2 308:1 304:M 298:1 286:2 276:2 271:1 267:M 248:2 245:= 219:1 198:2 194:2 190:2 186:1 154:1 72:) 66:( 61:) 57:( 43:.

Index

references
inline citations
improve
introducing
Learn how and when to remove this message
Shock wave around an aircraft
T-38
Schlieren photography
shock wave
normal shock
streamlines
supersonic
compressible flow
discontinuous
Galilean transformation


Mach number
continuity equation
tangential velocity component
Heat capacity ratio
numerical method
bow shock

Concorde

supersonic inlets
Concorde
F-14 Tomcat
Prandtl-Meyer expansion fans

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