scholarly journals Uncertainty Analysis of Supersonic Biplane's Aerodynamic Characteristics

2019 ◽  
Vol 37 (5) ◽  
pp. 909-917
Author(s):  
Hongyu Zhu ◽  
Gang Wang ◽  
Yi Liu ◽  
Boping Ma
Keyword(s):  
Mach Number ◽  
Uncertainty Quantification ◽  
Pressure Pulsation ◽  
Poor Performance ◽  
Aerodynamic Characteristics ◽  
Wave Drag ◽  
Normal Distributions ◽  
Global Sensitivity ◽  
Expansion Waves ◽  
Uncertainty Parameters

Utilizing the interference of shock and expansion waves, supersonic biplane can reduce the wave drag remarkably. However, the supersonic biplane is only designed at special conditions, so that it has poor performance at off-design conditions. To analyze supersonic biplane's aerodynamic characteristics at off-design conditions, the non-instructive probabilistic collocation method has been employed to achieve uncertainty quantification. Besides, Sobol global sensitivity is adopted to accurately evaluate the influence of the input uncertainty parameters. The uncertainty parameters are Mach number and the angle of attack which both satisfy special normal distributions. Aerodynamic coefficients and pressure distribution from the biplane's surface as well as flow filed are studied. The results of uncertainty quantification show that the main reason for aerodynamic characteristics fluctuations is the pressure pulsation from the maximum thickness of the lower airfoil's upper surface. The results of global sensitivity show that Mach number is the most important factor for the variation of aerodynamic performance.

Aerodynamic analysis and design of Busemann biplane: towards efficient supersonic flight

2011 ◽  
Vol 226 (2) ◽  
pp. 217-238 ◽  
Author(s):  
D Maruyama ◽  
K Kusunose ◽  
K Matsushima ◽  
K Nakahashi
Keyword(s):  
Mach Number ◽  
Design Method ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
The Body ◽  
Analysis And Design ◽  
Expansion Waves ◽  
Mach Numbers ◽  
Inverse Design Method

Aiming to realize a low-drag supersonic transport, Busemann biplane concept was adopted in this study. Two- and three-dimensional (2D and 3D) biplanes were analysed and designed to improve their aerodynamic performance using computational fluid dynamics. It was confirmed that 3D biplane wings have better aerodynamic-performance areas than 2D biplane airfoils. A winglet is also useful for improvement of their aerodynamic performance. Aerodynamic characteristics of these biplanes at their off-design conditions were also analysed. In 3D wings, a flow choking and its attendant hysteresis as starting problems, which arise when the biplanes accelerate from low Mach numbers, disappear at lower Mach numbers than those in 2D airfoils. It was confirmed that hinged slats and flaps are effective to settle these issues. Finally, interference effects of a body with the biplanes were investigated. When the biplane wings are affected by the expansion waves from the body, their aerodynamic performance at the design Mach number and the starting Mach number are better and lower than those of their isolated wings, respectively. A 3D biplane wing obtained by an inverse-design method was applied to the body. The wing of this wing–body configuration achieves higher aerodynamic performance than the 2D flat-plate airfoil at sufficient lift conditions, which is the almost identical performance of 2D biplane airfoils.

A numerical study on the single pulsed energy addition based unsteady wave drag reduction at varied hypersonic flow regimes

2020 ◽  
pp. 095441002097313
Author(s):  
Dathi SNV Rajasekhar Rao ◽  
Bibin John
Keyword(s):  
Steady State ◽  
Mach Number ◽  
Drag Reduction ◽  
Shock Layer ◽  
Blunt Body ◽  
Wave Drag ◽  
Flow Features ◽  
Energy Pulse ◽  
Energy Addition ◽  
Wave Drag Reduction

In this study, unsteady wave drag reduction in hypersonic flowfield using pulsed energy addition is numerically investigated. A single energy pulse is considered to analyze the time-averaged drag reduction/pulse. The blast wave creation, translation and its interaction with shock layer are studied. As the wave drag depends only on the inviscid aspects of the flowfield, Euler part of a well-established compressible flow Navier-Stokes solver USHAS (Unstructured Solver for Hypersonic Aerothermodynamics) is employed for the present study. To explore the feasibility of pulsed energy addition in reducing the wave drag at different flight conditions, flight Mach numbers of 5.75, 6.9 and 8.0 are chosen for the study. An [Formula: see text] apex angle blunt cone model is considered to be placed in such hypersonic streams, and steady-state drag and unsteady drag reductions are computed. The simulation results indicate that drag of the blunt-body can be reduced below the steady-state drag for a significant period of energy bubble-shock layer interaction, and the corresponding propulsive energy savings can be up to 9%. For energy pulse of magnitude 100mJ deposited to a spherical region of 2 mm radius, located 50 mm upstream of the blunt-body offered a maximum percentage of wave drag reduction in the case of Mach 8.0 flowfield. Two different flow features are found to be responsible for the drag reduction, one is the low-density core of the blast wave and the second one is the baroclinic vortex created due to the plasma energy bubble-shock layer interaction. For the same freestream stagnation conditions, these two flow features are noted to be very predominant in the case of high Mach number flow in comparison to Mach 5.75 and 6.9 cases. However, the ratio of energy saved to the energy consumed is noted as a maximum for the lower Mach number case.

Experiments of Compressible Homogeneous and Isotropic Turbulence Interacting With Expansion Waves

2003 ◽  
Author(s):  
Savvas S. Xanthos ◽  
Yiannis Andreopoulos
Keyword(s):  
Mach Number ◽  
Shock Tube ◽  
Total Pressure ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Pressure Fluctuations ◽  
Incident Shock ◽  
Expansion Waves ◽  
Curvature Effects ◽  
Homogeneous And Isotropic Turbulence

The interaction of traveling expansion waves with grid-generated turbulence was investigated in a large-scale shock tube research facility. The incident shock and the induced flow behind it passed through a rectangular grid, which generated a nearly homogeneous and nearly isotropic turbulent flow. As the shock wave exited the open end of the shock tube, a system of expansion waves was generated which traveled upstream and interacted with the grid-generated turbulence; a type of interaction free from streamline curvature effects, which cause additional effects on turbulence. In this experiment, wall pressure, total pressure and velocity were measured indicating a clear reduction in fluctuations. The incoming flow at Mach number 0.46 was expanded to a flow with Mach number 0.77 by an applied mean shear of 100 s−1. Although the strength of the generated expansion waves was mild, the effect on damping fluctuations on turbulence was clear. A reduction of in the level of total pressure fluctuations by 20 per cent was detected in the present experiments.

Aerodynamic optimisation of the rocket plane in subsonic and supersonic flight conditions

2017 ◽  
Vol 231 (12) ◽  
pp. 2266-2281 ◽  
Author(s):  
Marcin Figat ◽  
Agnieszka Kwiek
Keyword(s):  
Mach Number ◽  
Main Part ◽  
Numerical Study ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Design ◽  
Supersonic Speed ◽  
Supersonic Flight ◽  
Special Vehicle ◽  
Speed Regime ◽  
The Impact

This paper presents the results of a numerical study of the aerodynamic shape of the Rocket Plane LEX. The Rocket Plane is a main part of the Modular Airplane System – MAS; a special vehicle devoted to suborbital tourist flights. The Rocket Plane was designed for subsonic and supersonic flight conditions. Therefore, the impact of the Mach number should be considered during the aerodynamic design of the Rocket Plane. The main goal of the investigation was to determine the sensitivity of the Rocket Plane aerodynamic characteristics to the Mach number during the optimisation of the LEX geometry. The paper includes results of the optimisation process for Mach number from the range Ma = 0.5 to Ma = 2.5. These results reveal that the aerodynamic characteristics of models optimised for the subsonic and transonic regime of Mach numbers (up to Ma = 1) were also improved for the supersonic speed regime. However, in the case of models optimised for the supersonic flight regime the aerodynamic characteristics in subsonic flight regime, are inferior compared to the model before the optimisation process.

The Aerodynamic Characteristics of the Pantograph When the Train Passes Through the Tunnel

2017 ◽  
Author(s):  
Dilong Guo ◽  
Wen Liu ◽  
Junhao Song ◽  
Ye Zhang ◽  
Guowei Yang
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Maximum Amplitude ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Expansion Waves ◽  
Compression And Expansion ◽  
High Speed Trains ◽  
Current Characteristics ◽  
Pass Through

The aerodynamic force acting on the pantograph by the airflow is obviously unsteady and has a certain vibration frequency and amplitude, while the high-speed train passes through the tunnel. In addition to the unsteady behavior in the open-air operation, the compressive and expansion waves in the tunnel will be generated due to the influence of the blocking ratio. The propagation of the compression and expansion waves in the tunnel will affect the pantograph pressure distribution and cause the pantograph stress state to change significantly, which affects the current characteristics of the pantograph. In this paper, the aerodynamic force of the pantograph is studied with the method of the IDDES combined with overset grid technique when high speed train passes through the tunnel. The results show that the aerodynamic force of the pantograph is subjected to violent oscillations when the pantograph passes through the tunnel, especially at the entrance of the tunnel, the exit of the tunnel and the expansion wave passing through the pantograph. The changes of the pantograph aerodynamic force can reach a maximum amplitude of 106%. When high-speed trains pass through tunnels at different speeds, the aerodynamic coefficients of the pantographs are roughly the same.

Influence of Skewing of Contact Face on Performance of Wave Rotor Refrigerators and Superchargers

2013 ◽  
Author(s):  
Yuqiang Dai ◽  
Fengxia Liu ◽  
Jintao Wu ◽  
Wei Wei ◽  
Dapeng Hu ◽  
...  
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Shock Waves ◽  
Rotational Speed ◽  
Channel Width ◽  
Wave Rotor ◽  
Coriolis Forces ◽  
Local Loss ◽  
Expansion Waves ◽  
Pressure Port

As a novel generation of rotational gas wave machines, wave rotor machines such as wave rotor refrigerators (WRR) and wave rotor superchargers (WRS) are unsteady flow devices. In their passages two gas streams (with different pressure or even different phases) comes into direct contact can exchange energy due to the movement of shock waves and expansion waves. A detailed study shows that, when rotor channels open to the high pressure port gradually, the contact face in rotor channels inevitably skews, which is always accompanied with reflection of shockwaves. This causes very large energy dissipation and influences adversely on the refrigeration performance of WRR or the supercharging performance of WRS. In this work, factors such as centrifugal forces, Coriolis forces, gradual channel opening and gradual channel closing, etc, which influence the wave transportation and skewing of shock waves and contact faces are studied by means of computational fluid dynamics and experiments. The skewing of contact faces causes uneven distribution of velocity and large local loss. With rotation Mach number smaller than 0.3, the skewing of contact face can be alleviated. To reduce the adverse influence of rotation Mach number, a smaller rotor channel width or higher rotational speed is necessary. The rotation effect plays an important role for the skewing of gas discontinuities. Both the centrifugal and Coriolis forces of wave rotor cannot be ignored with the Rossby number of 1.3∼3.5. To reduce the skewing loss of contact face, a lower rotational speed seems necessary. The rotation speed of wave rotors has dialectical influences on the skewing of shock waves and contact faces. The jetting width of high pressure port is the key factor of the gradual opening of rotor channels. A feasible way to reduce skewing losses of gas waves is to optimize the ratio between high pressure port width and channel width. The validation experiments have got at least 3∼5% rise of isentropic efficiency for WRRs.

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