Low speed longitudinal dynamic stability analysis of a hypersonic waverider using unsteady Reynolds averaged Navier Stokes forced oscillation simulations

2020 ◽  
Vol 103 ◽  
pp. 105883 ◽  
Author(s):  
Tamas Bykerk ◽  
Dries Verstraete ◽  
Johan Steelant
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Forced Oscillation ◽  
Navier Stokes ◽  
Low Speed ◽  
Longitudinal Dynamic ◽  
Reynolds Averaged Navier Stokes

scholarly journals A numerical study into the longitudinal dynamic stability of the tailless aircraft

2019 ◽  
Vol 91 (3) ◽  
pp. 428-436 ◽  
Author(s):  
Agnieszka Kwiek
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Numerical Study ◽  
Aircraft Design ◽  
Content Type ◽  
Preliminary Stage ◽  
Longitudinal Dynamic ◽  
Stability Derivatives ◽  
The Impact ◽  
Tailless Aircraft

Purpose The purpose of this research is a study into a mathematical approach of a tailless aircraft dynamic stability analysis. This research is focused on investigation of influence of elevons (elevator) on stability derivatives and consequently on the aircraft longitudinal dynamic stability. The main research question is to determine whether this impact should be taken into account on the conceptual and preliminary stage of the analysis of the longitudinal dynamic stability. Design/methodology/approach Aerodynamic coefficients and longitudinal stability derivatives were computed by Panukl (panel methods). The analysis of the dynamic stability of the tailless aircraft was made by the Matlab code and SDSA package. Findings The main result of the research is a comparison of the dynamic stability of the tailless aircraft for different approaches, with and without the impact of elevator deflection on the trim drag and stability derivatives. Research limitations/implications This paper presents research that mostly should be considered on the preliminary stage of aircraft design and dynamic stability analysis. The impact of elevons deflection on the aircraft moment of inertia has been omitted. Practical implications The results of this research will be useful for the further design of small tailless unmanned aerial vehicles (UAVs). Originality/value This research reveals that in case of the analysis of small tailless UAVs, the impact of elevons deflection on stability derivatives is bigger than the impact of a Mach number. This impact should be taken into consideration, especially for a phugoid mode.

scholarly journals Conceptual design of an aircraft for Mars mission

2019 ◽  
Vol 91 (6) ◽  
pp. 886-892
Author(s):  
Agnieszka Kwiek
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Conceptual Design ◽  
Design Stage ◽  
Content Type ◽  
Mars Mission ◽  
Longitudinal Dynamic ◽  
Short Period ◽  
The Impact ◽  
Tailless Aircraft

Purpose The purpose of this paper is to present the results of a conceptual design of Martian aircraft. This study focuses on the aerodynamic and longitudinal dynamic stability analysis. The main research questions are as follows: Does a tailless aircraft configuration can be used for Martian aircraft? How to the short period characteristic can be improved by side plates modification? Design/methodology/approach Because of a conceptual design stage of this Martian aircraft, aerodynamic characterises were computed by the Panukl package by using the potential flow model. The longitudinal dynamic stability was computed by MATLAB code, and the derivatives computed by the SDSA software were used as the input data. Different aircraft configurations have been studied, including different wing’s aerofoils and configurations of the side plate. Findings This paper presents results of aerodynamic characteristics computations and longitudinal dynamic stability analysis. This paper shows that tailless aircraft configuration has potential to be used as Martian aircraft. Moreover, the study of the impact of side plates’ configurations on the longitudinal dynamic stability is presented. This investigation reveals that the most effective method to improve the short period damping ratio is to change the height of the bottom plate. Practical implications The presented result might be useful in case of further design of the aircrafts for the Mars mission and designing the aircrafts in a tailless configuration. Social implications It is considered by the human expedition that Mars is the most probable planet to explore. This paper presents the conceptual study of aircraft which can be used to take the high-resolution pictures of the surface of Mars, which can be crucial to find the right place to establish a potential Martian base. Originality/value Most of aircrafts proposed for the Mars mission are designed in a configuration with a classic tail; this paper shows a preliminary calculation of the tailless Martian aircraft. Moreover, this paper shows the results of a dynamic stability analysis, where similar papers about aircrafts for the Mars mission do not show such outcomes, especially in the case of the tailless configuration. Moreover, this paper presents the results of the dynamic stability analysis of tailless aircraft with different configurations of the side plates.

Performance of Unsteady Reynolds-Averaged Navier-Stokes and Hybrid Scale-Resolving Simulation Approaches in Simulating a Low-Speed Axial Compressor Rotor

2021 ◽  
Author(s):  
Xiangyi Chen ◽  
Björn Koppe ◽  
Martin Lange ◽  
Wuli Chu ◽  
Ronald Mailach
Keyword(s):  
Experimental Data ◽  
Turbulence Modeling ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Low Speed ◽  
Turbulent Characteristics ◽  
Sst Model ◽  
Reynolds Averaged Navier Stokes ◽  
Sas Model ◽  
Les Model

Abstract Aerodynamics phenomena in compressors are highly unsteady and turbulent. Selecting a proper turbulence-modeling method is significant to reveal the complex flow mechanism in turbomachines. In the current paper, the shear stress transport (SST) model as an unsteady Reynolds-averaged Navier-Stokes (RANS) method, the scale-adaptive simulation (SAS) model, and the zonal wall-modeled large eddy simulation (zonal-LES) as two hybrid scale-resolving simulation approaches have been compared. These turbulence-modeling methods were employed to simulate a single rotor of a low-speed research compressor featuring a tip clearance of 1.3% of chord length. Comparisons were made between the simulation results and the experimental data at three operating points, and the flow fields at the design point have been specifically discussed in detail. The results show that the advantage of the zonal-LES model becomes obvious as the compressor throttles. The zonal-LES model brings a significant improvement over both the SST model and the SAS model in capturing the experimental data, especially the velocity distribution in the low-span region, as well as the loss near the endwalls. The SAS model as a scale-resolving method presents no benefits in predicting the relevant flow compared with the SST model, as the activation of the SAS source term is limited for this test case. For the loss prediction, the variation in the upper half-span region is mainly due to the different results in modeling turbulent characteristics of the tip leakage flow, whereas the mechanism behind the higher loss at the lower half-span predicted by the zonal-LES model is a consequence of the complex topology of the corner separation and the intensive mixing.

A hybrid viscous body force model for low-speed centrifugal compressors

2020 ◽  
pp. 095765092094426 ◽  
Author(s):  
Zhiyuan Liu ◽  
Qingjun Zhao ◽  
Xiaorong Xiang ◽  
Wei Zhao ◽  
Xiaoyong Zhou
Keyword(s):  
Body Force ◽  
Navier Stokes ◽  
Force Model ◽  
Tip Leakage Flow ◽  
Centrifugal Compressors ◽  
Low Speed ◽  
Force Method ◽  
Body Force Method ◽  
Body Forces ◽  
Reynolds Averaged Navier Stokes

The flow in centrifugal compressors is viscous and unsteady. Flow separation off the blades challenges the accuracy of simulations. A viscous body force model is expected to speed up numerical convergence and reduce the computational costs of unsteady simulations. In this paper, both stability and accuracy of the viscous body force model are investigated based on the case of a low-speed centrifugal compressor. First, two formulations of the viscous body forces are obtained from the expression of the viscous flux. Then, the numerical stability of two body force models is found to be related to drag coefficient and flow angle. For large negative drag coefficients, the viscous body forces would lead to divergences. Since unsteady Reynolds-averaged Navier–Stokes simulations show that two formulas have considerable accuracy, stability is considered as the main factor for modeling. With the findings, a hybrid viscous body force method is proposed. To assess the applicability of the hybrid model, two test cases are compared against the results obtained by unsteady Reynolds-averaged Navier–Stokes simulations. The first case is the capability evaluation of unsteady characteristics capture for low-speed centrifugal compressors. The simulation results show that the hybrid viscous body force model can capture main unsteady viscous characters, including wake vortexes and tip leakage flow. The other is the case in which the inlet total pressure is disturbed. It is found that fluctuations of pressure, temperature, and velocity predicted by the viscous body force method are close to unsteady Reynolds-averaged Navier–Stokes results. In addition, the time-accurate overall performance of the compressor with disturbance is also predicted satisfactorily. With the advantage in lowering computer resource requirement, the viscous body force model is a promising method for long length scale unsteady cases.

Sign in / Sign up

Export Citation Format

Share Document