Papers by Author: Wei Qiang Liu

Abstract: Typical combustible particle coal has been analyzed by using turbulence-chemistry interaction models to realize which models are more accurate and reasonable on pulverized coal MILD combustion. Three turbulence-chemistry interaction models are examined: the Equilibrium Mixture Fraction/PDF (PDF), the Eddy Break Up (EBU), the Eddy Dissipation Concept (EDC). All of three models can give a suitable prediction of axial velocity on combustible particle coal MILD combustion because turbulence-chemistry interaction models have little influence on flow field and flow structure. The Eddy Dissipation Concept model (EDC), based on advanced turbulence-chemistry interaction with global and detailed kinetic mechanisms can produce satisfactory results on chemical and fluid dynamic behavior of combustible particle coal MILD combustion, especially on temperature and species concentrations.

Abstract: Four turbulent models are introduced. The hypersonic aerodynamic heating calculation results by Shear Stress Transport (SST) turbulent model of different grid scale shows that near wall y+ spacing approximate to one third of the upper limit prescribed by turbulent model. Then, the comparison of the hypersonic aerodynamic heating calculation results by different turbulent model and the test data shows that SST turbulent model can give an enough accurate result.

Abstract: Forward-facing cavity mounted on the blunt nose of hypersonic vehicle is a good choice to reduce the stagnation heating. Presently, the study on hypersonic vehicles nose tip with forward-facing cavity mainly focus on its thermology characteristic, and little work can be found investigating the effect of cavity on aerodynamic force for a holistic vehicle. The CFD method is developed to investigate the effect of cavity geometry on aerodynamic performance of hypersonic vehicle with a forward-facing cavity on the nose-tip. Drag coefficient, lift coefficient and pitching moment coefficient of the vehicle for different attack angle are calculated. It is found that the cavity length to diameter (L/D) can not be a characteristic parameter in aerodynamic research, though it was used as a main characteristic parameter in investigation on the thermal protection. The length of the cavity L has little effect on aerodynamic characteristic of the vehicle, and the cavity diameter D has a crucial influence on the aerodynamic performance and the aerodynamic performance decrease with the D increasing. With the attack angle increasing, the drag coefficient, lift coefficient, pitching moment coefficient and lift-drag ratio of the hypersonic vehicle all increase.

Abstract: To study the effects of wall thickness, rib height and groove width on cooling effect and pressure drop, three dimensional heat transfer of liquid propellant rocket engine with cooling groove is numerically investigated using gas-solid-liquid coupled heat transfer model. The one-dimensional model is adopted to describe the coolant flow and 3D heat transfer model is used to calculate the coupling heat transfer through the wall. In this text, wall thickness, rib height and groove width varied while the groove number is fixed and coolant mass flow rate remains constant. When liner material is QZr0.2 alloy, we find the optimal design point of the aspect ratio. Moreover, a fitting function of the optimal aspect ratio is acquired. The biggest error of the fitting function is 3.3% compared with numerical results.

Abstract: By the uses of finite element method and finite volume method, we calculated the solid domain and fluid domain of windward leading edge which is flying under one condition. And the paper proved that heat pipes which covered on the leading edge have effect on thermal protection. The maximum temperature of the head decreased 12.2%. And the minimum temperature of after-body increased 8.85%. Achieving the transfer of heat from head to after-body, the front head of the thermal load was weakened and the ability of leading edge thermal protection was strengthen. The effect of the thickness of heat pipe, black level of covering materials and equivalent thermal conductivity of heat pipes on the wall temperature were discussed for the selection of thermal protection materials of windward leading edge to provide a frame of reference.

Abstract: Two-dimensional transient heat transfer model of the plug of regenerative cooling plug nozzle is built. Based on the convective heat-transfer coefficient and the radiation heat flux obtained using analytic method and axisymmetric unstructured Delaunay grid applied to mesh the simplified physical model, numerical simulations of transient temperature field and thermal distortion are carried out by finite element method combined with thermal-structure coupling theory. Not only the results of numerical calculation under working conditions with and without regenerative cooling, but the results under low and high working conditions are compared. The results shows that thermal distortion can be reduced effectively when regenerative cooling method is adopted in the throat and combustion chamber that have the most serious thermal condition.

Abstract: To obtain temperature distribution in regenerative-cooled liquid propellant rocket nozzle quickly and accurately, three-dimensional numerical simulation employed using empirical formulas. A reduced one-dimensional model is employed for the coolant flow and heat transfer, while three dimensional heat transfer model is used to calculate the coupling heat transfer through the wall. The geometrical model is subscale hot-firing chamber. The numerical results agree well with experimental data, while temperature field in nozzle obtained. In terms of computing time and accuracy of results, this method can provide a reference for optimization design and performance estimation.

Abstract: Platelet transpiration cooling is one of the key techniques for the developing reusable launch vehicle. The thinner of the platelet, the better effect plate transpiration will gain. Meanwhile, the platelet unit may get wrinkled if thermal stress is large enough. One-dimensional non-equilibrium model is adopted to analyze the heat transfer characteristics of platelet transpiration cooling. The assumption of rectangular plate with three-side simple supported and one-side free is taken and Galerkin method is applied for analyzing the stability of platelet unit. Analysis indicates that as the heat transfer intensity increases, the thermal soaking depth decreases, while more coolant is needed to keep the heated wall at design temperature. Also, the critical thickness for the platelet not to get wrinkled gets larger with the increasing thermal soaking depth.

Abstract: The GO2/ethanol/water tripropellant evaporation and combustion in axisymmetric combustion chamber was numerically simulated. The different characteristics of the evaporation and combustion between dilative and traditional un-dilative entrance, and the different dilation-angles of the combustion chamber entrance are analyzed. The results indicate that the dilative entrance combustion chamber is benefit for thermal protection of the injection, and the flamelet backpedals with increase of the entrance dilation-angle. At the same time, that dilative inlet combustion chamber reduces the evaporation of the liquid component seriously. The evaporation rate decreases with the increase of the dilation-angle at first, but after the dilation-angle is bigger than a critical one, it increases.

Abstract: Under thermal stress, the formed platelet of Liquid Rocket Engine (LRE) transpiration cooling structure may result in wrinkling. The stability of rectangular sheet with three simple supported-sides and one free-side is simplified as the model of formed platelet. Applying the Galerkin method for analysis, the relationship of the critical thickness of formed platelet and the transpiration width is obtained. Also, the influence of different material properties on the critical thickness is presented. The theory and method proposed in this paper are applicable for more complicated temperature distribution and also can be used to choose material for transpiration cooling.