1、Lessons Learned Entry: 0337Lesson Info:a71 Lesson Number: 0337a71 Lesson Date: 1994-07-13a71 Submitting Organization: LARCa71 Submitted by: Bernard LewisSubject: A Colored Water Technique for Analyzing Complex Flow Fields Description of Driving Event: For many years, LARC has been studying cavity fl
2、ow fields at supersonic speeds. This research has included various flow visualization wind tunnel tests to document both the cavity surface and off-body flow fields. During one of these tests, water was injected through pressure measurement orifices located on the model surface in an attempt to visu
3、alize vortices that typically form above certain cavity configurations. Because of the low static pressure in the tunnel, it was anticipated that the water would vaporize as it exited the orifice and the resulting vapor would be entrained into the vortices and render them visible. This technique did
4、 not work, and the water instead flowed along the model surface. Although the water was difficult to discern against the model surface, it was obvious that the water was being entrained by the model surface flows and had a fast response to the cavity flow unsteadiness. This impetus led to the develo
5、pment of a technique that uses colored water as a medium to visualize surface flows over wind tunnel models.The colored water surface flow visualization technique basically involves injecting colored water through the pressure measurement orifice tubes installed in a wind tunnel model. The colored w
6、ater exits the orifices and flows along the model surfaces to form streaklines. The resulting flow patterns are then photographed for later analysis. This method has several advantages over the conventional oil flow and tuft techniques that can make it a useful procedure for routine testing.Lesson(s
7、) Learned: A colored water technique which complements the oil flow and tuft techniques and gives researchers another test method to analyze complex flow fields, has been developed by NASA LARC researchers.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networking permitted withou
8、t license from IHS-,-,-Wind tunnel tests have been conducted using this technique to visualize surface flows at supersonic speeds in a rectangular box cavity that was mounted in a flat plate. Both video and still photographs of the resultant flow fields were obtained.Evidence of Recurrence Control E
9、ffectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Aircrafta71 Test Facilitya71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1994-08-11a71 Approval Name: Charles Cockrella71 Approval Organization: AFa71 Approval Phone Number: 804-864-3361Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
