ArE 311L & ArE343L Lctur Nots Lctur # 1: Shock Wavs and D Laval Nozzl Dr. Hui H Hu Dpartmnt of Arospac Enginring Iowa Stat Univrsity Ams, Iowa 50011, U.S.A
ArE311L Lab#3: rssur Masurmnts in a d Laval Nozzl Tank with comprssd air Tst sction Tap No. Distanc downstram of throat (inchs) Ara (Sq. inchs) 1-4.00 0.800-1.50 0.59 3-0.30 0.480 4-0.18 0.478 5 0.00 0.476 6 0.15 0.497 7 0.30 0.518 8 0.45 0.539 9 0.60 0.560 10 0.75 0.581 11 0.90 0.599 1 1.05 0.616 13 1.0 0.67 14 1.35 0.63 15 1.45 0.634
1st, nd and 3 rd critic conditions st critic condition 0 incrasing 1st critic condition 0 incrasing 3st critic condition
ArE311L Lab#4: rssur Masurmnts in a d Laval Nozzl 1. Undr-xpandd xpandd flow. 3rd critical 3. Ovr-xpandd xpandd flow with obliqu shocks 4. nd critical 5. Normal shock xisting insid th nozzl 6. 1st critical Rquird lots: lots of th masurd prssur (static and total prssur) as a function of distanc along th nozzl axis for th cass, 4, 5 and 6. lots of th thortically prdictd prssur (static and total prssur) as a function of distanc along th nozzl axis for th cass, 4, 5 and 6. lots with th masurd and prdictd valus of th wall prssur distribution on th sam graphs for th cass, 4, 5 and 6 for comparison. lots of th thortically prdictd and masurd Mach numbr as a function of distanc along th nozzl axis for th cass, 4, 5 and 6.
1st, nd and 3 rd critic conditions nd critical shock is at nozzl xit Flow clos to 3 rd critical Ovr-xpandd xpandd flow with shock btwn nozzl xit and throat Undr- xpandd flow Ovr- xpandd flow 1 st critical shock is almost at th nozzl throat.
rdiction of th rssur Distribution within a D Laval Nozzl by using Numrical Approach Throat, A* or A t T1 M<1 M>1 Shock A S T1 1 T M<1 A = atm = atm Using th ara ratio, th Mach numbr at any point up to th shock can b dtrmind: A * A = γ + 1 1 1 1 γ γ 1 + M M γ + 1 Aftr finding Mach numbr at front of shock, calculat Mach numbr aftr shock using: M γ 1 1+ M1 = γ 1 γ M1 Thn, calculat th A * γ 1 A = M As 1+ M γ + 1 ( ) γ + 1 γ 1 which allows us calculat th rmaining Mach numbr distribution A * A = γ + 1 1 1 1 γ γ 1 + M M γ + 1
rdiction of th rssur Distribution within a D Laval Nozzl by using Numrical Approach Throat, A* or A t T1 Shock A S 1 T1 T M<1 M>1 M<1 T A = atm = atm a.for 3rd Critical
rdiction of th rssur Distribution within a D Laval Nozzl by using Shock Tabl Mthod Throat, A* or A t T1 M<1 M>1 Shock A S T T1 1 T M<1 A = atm = atm mthod #1, by using quations: If th shockwav is locatd at position of tab#1: Mthod #: by using Isntropic Flow proprtis tabl (Appndix-A A of Andrson s s txtbook)
rdiction of th rssur Distribution within a D Laval Nozzl by using Shock Tabl Mthod By using th normal shock tabls with M1 = 1.64 w find that M = 0.686. (Appndix-B B of Andrson s s txtbook) Nxt, w find th sonic rfrnc ara bhind th shock using th ara-mach rlation. i.., M=0.686 (Appndix-A A of Andrson s s txtbook) Find sonic rfrnc bhind th shock using th ara-mach rlationship: i.., A*=0.557sq. Inchs If th shockwav is locatd at position of tab#1:
rdiction of th rssur Distribution within a D Laval Nozzl by using Shock Tabl Mthod With th xit prssur to b sa- lvl standard prssur. W now calculat th total prssur bhind th shock using this valu of xit prssur and th prssur ratio at th xit: t 1 t = = 14.7 = 19.53 0.758 Our last major task is to find th total prssur ahad of th shock, t1 = t1 1 t1 t 1 t
Som xampls of prvious studnt lab rports Thortical Data - Gaug rssur vs. osition 50 40 Gaug rssur, psi 30 0 10 0 35 30 Exprimntal 1-D Thory -10 0 1 3 4 5 osition along Nozzl Axis, inchs 3rd Critical nd Critical Normal Shock 1st Critical rssur (SI) 5 0 15 10 Gaug rssur, psi Exprimntal Rsults - rssur vs. Nozzl Location 90 80 70 60 50 40 30 0 10 0-10 0 1 3 4 5 Nozzl location, inchs 5 Total rssur = 34.336 SI 0-5 -4-3 - -1 0 1 Distanc from Troat (in) Undr-Expandd Flow Approximatly nd Critical Normal Shock