1、NASA TECHNICAL NASA TM X-3222M E M OR“AN.D U MNIS(NASA-TM-X-3222) EFFECT OF ENTRY-LIP DESIGN N75-22278ON AERODYNAMICS AND ACOUSTICS OF HIGH THROATM ACH NUMBER INLETS FOR THE QUIET, CLEAN,SHORT-HAfL EXPERIMENTAL ENGINE (NASA) 45 p UnclasHC $3.75 CSCL 01A H1/02 21039EFFECT OF ENTRY-LIP DESIGNON AERODY
2、NAMICS AND ACOUSTICSOF HIGH-THROAT-MACH-NUMBER INLETSFOR THE QUIET, CLEAN, SHORT-HAULEXPERIMENTAL ENGINEBrent A. Miller, Benjamin J. Dastoli,and Howard L. Wesoky -Lewis Research Center “Cleveland, Ohio 44135NATIONAL AERONAUTICS AND SPACE ADMINISTRATION * WASHINGTON, D. C. * MAY 1975Provided by IHSNo
3、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Report No. 2. Government Accession No. 3. Recipients Catalog No.NASA TM X-32224. Title and Subtitle EFFECT OF ENTRY-LIP DESIGN ON AERODY- 5. Report DateNAMICS AND ACOUSTICS OF HIGH-THROAT-MACH-NUMBER May 1975INLETS F
4、OR THE QUIET, CLEAN, SHORT-HAUL 6. Performing Organization CodeEXPERIMENTAL ENGINE7. Author(s) 8. Performing Organization Report No.Brent A. Miller, Benjamin J. Dastoli, and Howard L. Wesoky E-816010. Work Unit No.9. Performing Organization Name and Address 505-03Lewis Research Center 11. Contract o
5、r Grant No.National Aeronautics and Space AdministrationCleveland, Ohio 44135 13. Type of Report and Period Covered12. Sponsoring Agency Name and Address Technical MemorandumNational Aeronautics and Space Administration 14. Sponsoring Agency CodeWashington, D. C. 2054615. Supplementary Notes16. Abst
6、ractResults of scale model tests of high-throat-Mach-number inlets designed to suppress inlet-emitted engine machinery noise conducted in the Lewis 2. 74- by 4. 58-meter (9- by 15-ft)V/STOL wind tunnel are presented. A vacuum system was used to induce inlet airflow witha siren as a noise source. Inl
7、et mass flow was 11. 68 kilograms (25. 75 ibm) per second ata throat Mach number of 0. 79. The effect of entry-lip design (contraction ratio and diam-eter ratio) on inlet total-pressure recovery, steady-state pressure distortion, performanceat high incidence angles, and noise suppression was determi
8、ned. With proper entry-lip de-sign, total-pressure recovery in excess of 0. 988 could be obtained statically at an averagethroat Mach number of 0. 79. Total-pressure distortion was 5 percent. The reduction in thesiren tone sound pressure lever transmitted through the inlet was 10 to 14 dB relative t
9、othat measured at throat Mach 0. 6. Good inlet performance was also obtained to high inci-dence angles at free-stream velocities of 41 and 61 meters per second. At an incidenceangle of 500, a throat Mach number of 0. 79, and a free-stream velocity of 41 meters persecond, total-pressure recovery was
10、0. 982 with a total-pressure distortion of 14 percent. Atthis condition the reduction in inlet-emitted siren tone sound pressure level was 23 decibelsrelative to that measured at 0. 6 throat Mach number.17. Key Words (Suggested by Author(s) 18. Distribution StatementInlet design Inlet lip design Unc
11、lassified - unlimitedSonic inlet High Mach number inlet STAR category 02 (rev.)Choked inlet Wind tunnel tests19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price*Unclassified Unclassified 44 $3. 75* For sale by the National Technical Information Serv
12、ice, Springfield, Virginia 22151Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EFFECT OF ENTRY-LIP DESIGN ON AERODYNAMICS AND ACOUSTICS OF HIGH-THROAT-MACH-NUMBER INLETS FOR THE QUIET, CLEAN,SHORT-HAUL EXPERIMENTAL ENGINEby Brent A. Miller, Benjamin
13、 J. Dastoli, and Howard L. WesokyLewis Research CenterSUMMARYScale model tests of high-throat-Mach-number inlets designed to suppress inlet-emitted engine machinery noise were conducted in the Lewis 2. 75- by 4. 58-meter (9- by15-ft) V/STOL wind tunnel. The tests were conducted to support the develo
14、pment of aquiet, clean, short-haul experimental engine (QCSEE). The effect of entry-lip designon inlet total-pressure recovery, steady-state total-pressure distortion, performance athigh incidence angles, and noise suppression was determined. Four entry lips weretested. Three had external forebody d
15、iameter ratios of 0. 905 and internal area contrac-tion ratios of 1. 37, 1.46, and 1. 56. The fourth had an external forebody diameter ratioof 0. 935 and a contraction ratio of 1. 46.At static conditions the two entry lips having a diameter ratio of 0. 905 and contrac-tion ratios of 1. 46 and 1. 56
16、generally showed the better performances. At 0. 79 throatMach number, these entry lips produced a pressure recovery in excess of 0. 988. Total-pressure distortion was approximately 5 percent. The noise transmitted through the in-let was reduced 10 to 14 decibels from the value at a throat Mach numbe
17、r of 0.6.The entry lips with contraction ratios of 1. 46 and 1. 56 and diameter ratio of 0. 905showed the best performance when subjected to an 18-meter-per-second (35-knot) 900crosswind. At these conditions separation-free operation was obtained over a widerange of average throat Mach numbers. Thes
18、e two entry lips also operated free fromlarge-scale flow separations at incidence angles in excess of 600, at a free-stream ve-locity of 41 meters per second (80 knots) and a throat Mach number of 0. 79. At a 500incidence angle, a 0. 79 throat Mach number and a 41-meter-per-second (80-knot) free-str
19、eam velocity, these entry lips produced a sound pressure level reduction of approxi-mately 23 decibels relative to that measured at throat Mach number of 0. 6. The corre-sponding total-pressure recovery was 0. 982 with a total-pressure distortion of approxi-mately 14 percent.Provided by IHSNot for R
20、esaleNo reproduction or networking permitted without license from IHS-,-,-INTRODUCTIONLewis Research Center and the General Electric Co., as primary contractor, aredeveloping the technology for a quiet, clean, short-haul, experimental engine (theQCSEE engine). Such an engine, intended for applicatio
21、n to short takeoff and landing(STOL) aircraft, requires a close integration of the engine and its nacelle. The QCSEEinlet, which is an important part of the nacelle, is the subject of this report.Two major factors contribute to making the inlet design more difficult for theQCSEE application than for
22、 conventional subsonic engines: the low noise goal set forthe aircraft that will use the QCSEE engine (ref. 1) and the large upwash angles gener-ated by STOL aircraft takeoff and landing operations (ref. 2).An appreciable reduction in inlet-emitted engine machinery noise must be made toenable a four
23、-engine aircraft to meet a noise goal of 95 effective perceived noise deci-bels (EPNdB) along a 152-meter (500-ft) sideline. Numerous investigations (refs. 3 to 8)have demonstrated that reductions in inlet-emitted engine noise can be achieved by in-creasing the inlet average throat Mach number above
24、 the values typically used with con-ventional inlets. A high-throat-Mach-number inlet was, therefore, selected for QCSEE.A design throat Mach number of 0. 79 was tentatively selected to be representative ofthis type of inlet (refs. 6 to 8). This compares with 0. 6 to 0. 7 for conventional sub-sonic
25、inlets.The large upwash angles generated by the high wing-lift coefficients characteristicof STOL aircraft operations are of concern to the inlet designer. Typical low-speedconditions at which the QCSEE inlets will be judged are static conditions, a 900 cross-wind at 18 meters per second (35 knots),
26、 and a 500 incidence angle at 41 meters persecond (80 knots). Reference 9 indicates that inlet performance at low forward speeds,especially at high incidence angles, is strongly affected by inlet entry-lip design. Pen-alties for unsatisfactory entry-lip design are a loss in engine thrust and stall m
27、argin,with possible increased engine noise generation (ref. 10) and vibration. The resultspresented in reference 11 indicate that entry-lip design also significantly affects theacoustic suppression properties of high-throat-Mach-number inlets. A properly de-signed entry lip is thus essential.The tas
28、k of designing an inlet capable of operating satisfactorily at the high throatMach numbers required for engine noise suppression while immersed in the high upwashflow characteristic of short-haul operation is difficult. An analytical study of proposedinlets for the QCSEE application (ref. 12) indica
29、ted that high surface Mach numbers andstrong adverse pressure gradients would be encountered on the inlet entry lip at theQCSEE low-speed operating conditions. No experimental data could be found for inletsdesigned to operate at these conditions.The purpose of the present investigation was to determ
30、ine experimentally the effectof entry-lip design on the low-speed performance of the high-throat-Mach-number inlet2Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-proposed for QCSEE. The inlets selected for testing were designed jointly by GeneralEle
31、ctric Co., Douglas Aircraft Company (a subcontractor), and Lewis Research Centerpersonnel. The scale model inlets were then tested in a 2. 74- by 4. 58-meter (9- by15-ft) V/STOL wind tunnel at Lewis. Measurements were made to determine inlet total-pressure recovery, steady-state total-pressure disto
32、rtion, incidence angle at flow sep-aration, and inlet-emitted noise. Two major entry-lip geometric variables were inves-tigated: the internal lip area contraction ratio and the external forebody diameter ratio.Three of the entry lips tested had internal lip contraction ratios of 1. 37, 1.46, and 1.
33、56.The external forebody diameter ratio of these lips was 0. 905. The effect of the externalforebody diameter ratio was investigated with a fourth entry lip where the ratio was0. 935. The contraction ratio of this entry lip was 1. 46.The four entry lips were tested with the same inlet centerbody and
34、 diffuser. Thediffuser-exit diameter was 30. 48 centimeters (12 in.). The tests were conducted with-out a fan by using a vacuum system and the appropriate valves and controls to induceinlet airflow. A siren was used to simulate engine machinery noise so that the noisesuppression properties of the in
35、lets could be determined. The inlets were tested attunnel airflow velocities of 0, 18, 41, and 61 meters per second (0, 35, 80, and 120knots) at incidence angles of 00 to 900. Inlet average throat Mach number was variedover a wide range both above and below the design value of 0. 79.SYMBOLSa major a
36、xis of internal lip (fig. 4)b minor axis of internal lip (fig. 4)D diametergmax inlet total-pressure distortion parameter, (maximum total pressure)- (minimum total pressure)/(average total pressure)L axial length of inlet (fig. 3)Mt one-dimensional average throat Mach numberp total pressurep static
37、pressureSPL sound pressure level, dBA(SPL)BPF reduction in one-third-octave band sound pressure level at siren bladepassing frequency, dBV velocity, m/sec (knots)x axial distance from inlet highlight (fig. 3)3Provided by IHSNot for ResaleNo reproduction or networking permitted without license from I
38、HS-,-,-Y external forebody thickness (fig. 4(a)a incidence angle (angle between free-stream velocity and inlet centerline), deg0m diffuser maximum local wall angle (fig. 3), degX external forebody length (fig. 4(a)/ inlet circumferential position, degSubscripts:c centerbodyd diffusere diffuser exith
39、l highlightm inlet maximumt throat0 free stream1 rake measuring planeAPPARATUS AND PROCEDURETest FacilityInlet tests were conducted in a 2. 74- by 4. 58-meter (9- by 15-ft) V/STOL windtunnel (ref. 13). A vacuum system was used in place of a fan or compressor to induceinlet flow. A schematic view of
40、the test installation and facility is shown in figure 1.A venturi, calibrated in place against a standard ASME bellmouth that had beencorrected for boundary-layer growth, was used to measure inlet airflow. The scatterin the airflow calibration data was approximately 0. 2 percent at the design inlet
41、massflow of 11. 68 kilograms per second (25.75 lbm/sec). Inlet airflow was remotely variedusing two butterfly valves arranged to give both course and fine adjustment. Inlet in-cidence angle was also remotely varied by mounting the test apparatus on a turntable.A swivel joint, containing a low-leakag
42、e-pressure seal, provided 3600 rotation capability.To determine the acoustic suppression properties of the inlet using the vacuum flowsystem a siren was installed in the duct downstream of the inlet. The siren was a13. 97-centimeter (5. 5-in.) diameter single-stage fan modified by the addition of st
43、rutsand a screen just upstream of the rotor to increase its noise level. The siren was lo-cated appproximately three inlet diameters downstream of the simulated fan face (fig. 1).Figure 1 also shows the microphones located in the wind tunnel approximately 20 meters4Provided by IHSNot for ResaleNo re
44、production or networking permitted without license from IHS-,-,-upstream of the test section. The microphones were used to measure the siren noisetransmitted through the inlet. A photograph of the model, as it appeared in the wind-tunnel test section, is shown in figure 2.Inlet DesignThe major varia
45、bles defining inlet design are shown in figure 3. The inlets testedhad a diffuser-exit diameter De (equivalent to the fan diameter) of 30. 48 centimetersand a throat diameter Dt of 25. 31 centimeters. At the model design throat Mach num-ber of 0. 79, inlet airflow was 11. 68 kilograms per second.In
46、keeping with the major objective of the test program (i. e., the selection of aninlet entry lip to permit high incidence angle operation) the inlets were fabricated inthree parts, allowing replacement of the entry lip. The three parts are the removableentry lip, the diffuser, and the nonrotating cen
47、terbody. Four entry lips, one diffuser,and one centerbody were tested.The variations in entry-lip design tested are shown schematically in figure 4. Fig-ure 4(a) shows the dimensions used to define the external forebody and internal lip pro-portions. Two major entry-lip geometric variables were inve
48、stigated: the internal liparea contraction ratio (Dhl/Dt)2 and the external forebody diameter ratio Dhl/Dm . Allentry lips were designed for cruise Mach numbers of approximately 0. 7. Three of theentry lips tested, designated by the numbers 1, 2, and 3, had respective internal liparea contraction ra
49、tios of 1. 37, 1. 46, and 1. 56. The external forebody diameter ratiofor these entry lips was 0. 905 with a forebody length to maximum diameter X/Dm of0. 2. These three entry lips are shown in figure 4(b). A fourth entry lip, number 4,had a diameter ratio of 0. 935 and a contraction ratio of 1. 46. The external forebodylength of this entry lip was 0. 175 times its maximum diameter. This entry lip is com-pared with
