Experimental Investigation of a Long Rise- Time Pressure Signature through Turbulent Medium

Transcription

1 Experimental Investigation of a Long Rise- Time Pressure Signature through Turbulent Medium Boeing Executive Seminar November 20 th 2014 Tohoku University Takahiro Ukai Institute of Fluid Science, Tohoku University, Japan

2 Super Sonic Transport (SST) 1 Requirements for SST Sonic boom reduction Low-fuel consumption Sonic boom signatures Concorde SST, (cited 19 January 2010) Normal Normal boom shape signature Rise time Low boom signature Overpressure

3 Estimation tools Sonic boom estimation 2 Numerical simulation Wind tunnel testing Design procedure JAXA HP Concept Sonic boom estimation Design Evaluation Manufacture Sonic boom estimation is important to realize SST

4 Effect of the real atmosphere Sonic boom propagating Real atmosphere Various conditions Turbulence Humidity Temperature 3 Carlson, NASA SP-147, p.10, (1967) The pressure waveforms affected by turbulence Lee et. al, AL-TR , (1991)

5 Rise-time Effect of turbulence Turbulence interaction Overpressure decreases Rise-time increases 4 Overpressure Normal sonic boom signature Low sonic boom signature Typical waveforms Turbulence effects Known Unknown

6 Phenomenon observed in flight tests 5 Estimated waveform Kenneth et al. AIAA paper (2004) Measured at the ground The low sonic boom signature is also affected by turbulence Plotkin et al. AIAA paper , (2005)

7 Laboratory-scale experiments 6 Spark generator Ballistic range Controllable turbulence Controllable turbulence Arbitrarily shaped Waveform Waveform with N-shape flow Wind tunnel Uncontrollable turbulence Ballistic ranges have ability to simulate turbulence Arbitrarily interaction shaped with a Waveform low sonic boom

8 7 Objective Investigate the effect of turbulence on a pressure signature with the long rise time in a ballistic range facility Evaluate a distortion of a waveform with N-shape Evaluate a distortion of a waveform with the long rise time

9 Experimental setup 8 Ballistic range in Institute of Fluid Science, Tohoku Univ. Flight Mach number up to 7.2 Projectile diameter of 15 mm Test section: L= 12 m, D= 1.66 m Measurement techniques Propellant chamber Recovery tank Launch tube Optical windows Pressure transducer: Pressure waveform PCB Piezotronics, INC. Model-113B28 Rise time under 1 μs, resolution of 7 Pa Schlieren photography and point diffraction interferometry : Density field HPV-X Shimadzu Corp., high-speed camera 200 kfps and the exposure time of 1 μs

10 Test section 9 Projectile Flight direction 140 Lasers Light source (green laser, λ = 532 nm) Flat mirror Expanding lens Paraboloidal mirror Blast tube Pressure transducer Jet nozzle 100 Pressure transducer Launch tube Jet nozzle Flight path Catch tank Imaging lens Pin hole High-speed camera Optical window Paraboloidal mirror Flat mirror

11 Projectiles 10 Polyamide resin Cylindrical projectile Polyamide resin Steel Conical projectile Setup flight Mach number of 1.4 and 1.5

12 U mean [m/s] Specification of jet impingement 11 Flight direction Projectile Jet nozzle x Shock wave 60kPa y 112, 102 Flash-mounted pressure transducer V rms /U mean Jet nozzle: 4.5 mm in inner diameter Jet gas: Dry air

13 Results

14 Schlieren image (Cylindrical projectile) 12 Flight direction Recompressed shock Cylindrical projectile Secondary shock Bow shock Pressure transducer Without shock-turbulence interaction, M = 1.50

15 Sequential PDI images 13 Δt = 0 μs Jet nozzle location Pressure transducer Δt = 25 μs Bow shock Δt = 125 μs Without interaction With interaction

16 ΔP (kpa) ΔP (kpa) ΔP (kpa) Processed pressure waveforms t [ms] Without turbulence t [ms] t [ms] With turbulence

17 Schlieren image (Conical projectile) Flight direction 15 Connection part Conical projectile Recompressed shock Expansion shock Primary shock Gap shocks Pressure transducer Without shock-turbulence interaction, M = 1.35

18 Without interaction With interaction Sequential schlieren images 16 Δt = 0 μs Primary shock Jet nozzle location Primary shock Pressure transducer Δt = 150 μs Gap shocks Primary shock Gap shocks Primary shock Δt = 200 μs Gap shocks Primary shock Distorted gap shocks Primary shock

19 ΔP [kpa] ΔP [kpa] Pressure waveforms 17 Gap shocks Recompressed shock 0.5 kpa Primary shock t [ms] Without interaction 0.5 kpa The turbulence effect was not critical issue t [ms] for the long rise time pressure signature With interaction

20 Summary 18 Turbulence effect on a pressure signature with the long rise time was experimentally investigated in a ballistic range facility The effect of turbulence on the N-shape waveform can be investigated in present experiment because of consistent with previous observation. The shock wave front was distorted by turbulence. The turbulence might not affect the pressure field generating the long rise time. Future works Evaluate statistics value for the effect of turbulence on the long rise time pressure signature. Define the standard for evaluation of the long rise time pressure signature.

21 Thank you for your attention Questions?