NASA-TN-D-523-1960 Investigation of the flow in a rectangular cavity in a flat plate at a mach number of 3 55《当马赫数为3 55时 平板中举行空腔中气流的研究》.pdf
《NASA-TN-D-523-1960 Investigation of the flow in a rectangular cavity in a flat plate at a mach number of 3 55《当马赫数为3 55时 平板中举行空腔中气流的研究》.pdf》由会员分享,可在线阅读,更多相关《NASA-TN-D-523-1960 Investigation of the flow in a rectangular cavity in a flat plate at a mach number of 3 55《当马赫数为3 55时 平板中举行空腔中气流的研究》.pdf(43页珍藏版)》请在麦多课文档分享上搜索。
1、NASA TN D-52: TECHNICAL NOTE 0-523 INVESTIGATION OF THE FLOW IN A RECTANGULAR CAVITY IN A FLAT PLATE AT A NlACH NUMBER OF 3.55 By Russell W. McDearmon Langley Research Center Langley Field, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON September i960 HASA-TN-D- 523) IN VESTIGATTON OF
2、THE PLOW 889-709 M IN A BECTANGULAR CAVITY IN A PLAT PLATE 8ACH NUMBEB OF 3.55 (NASA. I Langley Research Center) 43 p Unclas AT A 00/34 01990 38 c Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8 TECHNIC
3、AL NOTE D-523 . INVESTIGATION OF IXE FLOW IN A RECTANGULAR CAVITY IN A FLAT PLATE AT A MACH NUMBER OF 3.53 By Russell W. McDearmon SUMMARY An investigation has been made in the Mach 3.5 blowdown jet of the Langley High-Temperature Fluid Mechanics Section of the flow in a rectangular cavity in a flat
4、 plate. The results indicate that a criti- cal value of the ratio of depth to chord length existed between 0.093 and 0.146 such that the pressure distribution in the cavity was very sensitive to depth changes for ratios of depth to chord length less than the critical value and was insensitive to dep
5、th changes for ratios of depth to chord length greater than the critical value. tions had large effects on the pressure distribution only in the narrow cavities (cavities having ratios of span to chord length less than 0.25) at the moderately shallow depth (ratio of depth to chord length equal to 0.
6、093). Varying the upstream and downstream lip radii caused large changes in the pressure distribution only in the moderately wide (ratio of span to chord length equal to 0.75), moderately shallow cavity. Span varia- The critical depth of the cavity and the pressure distribution in the, very shallow
7、cavity (ratio of depth to chord length equal to 0.042) were predicted analytically over the supersonic Mach number range, and the predictions agreed with experiment at a Mach number of 3.55. The boundary layer of the flow approaching tne cavity v distances upstream of cavity lip are considered negat
8、ive, and distances downstream-of cavity lip are considered positive Y perpendicular distance above top of plate 6 thickness of boundary layer V Prandtl-Meyer angle (angle through which a supersonic stream is turned to expand from i.1 = 1 to ?I 1) cp Subscripts : two-dimensional flow-deflection angle
9、 through shock 0 1 conditions immediately upstream of cavity (fig. 11) conditions in upstream corner of very shallow cavity (fig. 11) 2 conditions in midportion of very shallow cavity (fig. 11) 3 corditions in downstream corner of very shallow cavity (fig. 11) Provided by IHSNot for ResaleNo reprodu
10、ction or networking permitted without license from IHS-,-,-4 4 W conditions immediately downstream of cavity (fig . 11) free-stream conditions * APPARATUS Wind Tunnel The tests were conducted in the Mach 3.5 blowdown jet of the Langley High-Temperature Fluid Mechanics Section. For this facility, dry
11、 air from high-pressure storage tanks is exhausted through a stagnation cham- ber to a nozzle with a rectangular test section about 5 inches square. The air then passes through a fixed diffuser to the atmosphere. pressure in the stagnation chamber can be controlled and held constant. The Models A dr
12、awing of the model is presented in figure 1. The pressure distributions in the cavity were obtained by means of 0.020-inch- diameter orifices in the model and a multiple-tube mercury manometer. The locations of the orifices are given in figure 2. The various depths of the cavity and the provisions f
13、or varying the upstream and downstream lip radii are also shown in figure 2. 0 The cavity was located in the plate so that the Mach lines from the corners of the leading edge fell outside of the cavity side faces. The model was made of steel and the top of the plate and the interior surfaces of the
14、cavity were highly polished. The leading edge of the plate was made as sharp as possible. the cavities were varied by means of metal inserts, and the span and lip-radii variations were obtained by using mahogany inserts. in the exposed surfaces resulting from the insertions were carefully filled in
15、with plaster. The depth and chord length of Any gaps All model configurations were tested with and without an aluminum- oxide transition strip on the plate (abbreviated “t.s.“ on the figures). The strip was approximately 0.007 inch thick; other dimensions and the locations of the strip are given in
16、figure 1. PRECIS ION . The estimated probable errors in the test parameters and variables are as follows: L 5 1 8 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-5 M. kO.05 For lCpl = 0.010 kO.0004 For ICpl = 0.200 kO.008 For lCpl = 1.300 kO.030 d/c
17、kO.001 b/c kO.O1 ru/c . kO.01 cp : x/c kO.002 rd/c . koa01 The angle of attack of the top of the flat plate was maintained at Oo, within +O.lO and -O.Oo. Throughout the tests the moisture content in the tunnel was ascer- tained (by dewpoint measurements) to be so low that the effects of condensation
18、 were negligible. RESULTS AND DISCUSSION Boundary Layer In order to identify the boundary layxr of the flow approaching (The exact location of the survey was 97 percent of the the cavity, pitot surveys were made immediately ahead of the upstream cavity lip. distance from the plate leading edge to th
19、e upstream cavity lip on the longitudinal center line of the plate.) without a transition strip affixed near the plate leading edge. Surveys were made with and The boundary-layer Mach number distributions obtained in tne surveys are presented in figure 3(a). strip had little effect on the shape of t
20、he curve, although it increased the boundary-layer thickness from approximately 0.043 inch to 0.054 inch. The presence of the transition Nondimensional velocity profiles were computed and are compared with theoretical laminar profiles from reference 8 and theoretical tur- bulent profiles in figure 3
21、(b). The experimental profiles with the transition strip off and on agree well with the 1/9-power turbulent profile; this indicates that natural transition from laminar to turbu- lent flow occurred on the plate upstream of the cavity. Pressure-distribution measurements ir, the cavity with the transi
22、- tion strip off and on were made over the range of depth, span, and Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 . (. lip-radii variations of the tests. effects on the pressure distributions; therefore the data with the tran- sition strip on wi
23、ll not be presented. The transition strip had negligible Effects of Depth on Flow in Cavity Pressure distributions.- The effects of depth on the pressure dis- tribution in the cavity are shown in figure 4. The data presented were obtained for the widest cavity tested for each chord length (b/c = 2.0
24、0 for c = 0.500 inch and c = 1.000 inch; b/c = 1.25 for L c = 1.500 inches) 5 data was minimized. 1 8 so that the influence of the cavity side faces on the Figure 4 shows that markedly different pressure distributions were obtained for d/c = 0.042 and d/c = 0.093. Increasing d/c from 0.093 to 0.146
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