Diverterless Supersonic Inlet Research Articles

Resolving puzzles in jet engines from history and future

In the past decades, taking an airplane has become one of the fastest travel methods, including transportation between two cities far away from each other or between two different countries across the earth. Jet engines take over most of the engine market on airplanes; while having over 20% of the cost to build a plane, economic efficiency is the first thing to consider. After that, due to the pollution of its fuel-burning process, environmentally friendly became another thing that needs to be valued. In this paper, the history and the basic principle of the jet engine will be demonstrated. Some recent improvements in jet engines would be provided, such as the Diverterless Supersonic Inlet (DSI) and a way to improve the components strength in building process solidification crystallization control technology. A way to improve both the service life and the component strength would be to discuss different materials, along with the looking-forward perspectives on jet engine advancement.

Numerical Simulation of a Y-Shaped Diverterless Supersonic Inlet

Three-dimensional (3-D) numerical simulations of a Y-shaped body-integrated diverterless supersonic inlet (DSI) have been investigated. A diverterless supersonic inlet is an external supersonic flow compression that uses a 3-D geometry of a bump for both supersonic flow compression and boundary-layer diversion. The simulations are performed in the presence of a typical body comprising an elliptical nose in order to model a more realistic approaching flow to the inlet entrance. All simulations were performed at a freestream Mach number of , the design Mach number, and at a 0 deg angle of attack (AOA) and 0 deg angle of sideslip (AOS). The Navier–Stokes relations along with shear stress transport equations are used to simulate turbulent flow on a multiblock structural grid. The present numerical simulation results show a good agreement with the wind-tunnel test data for the same DSI model. Moreover, the results show that the present numerical method has an acceptable accuracy in modeling a fully 3-D flow over the nose, along the supersonic compression region, and inside the inlet diffusers. The streamlines passed over the DSI supersonic compression clearly showed that the bump was successfully efficient in diverting the approaching boundary layer.

Symmetric and Asymmetric Performance Investigation of a Diverterless Supersonic Inlet

A series of wind-tunnel tests were conducted on a Y-shaped diverterless supersonic inlet (DSI) in order to investigate its performance at various operating conditions. The present DSI was designed for a freestream Mach number of . The experiments were performed at supercritical, critical, and subcritical operating conditions and at 0 deg angle of attack and angle of side slip. The results showed that the present DSI had an acceptable performance at its design condition. A symmetric supersonic flow pattern was observed at both supercritical and critical operating conditions. At low subcritical operating conditions, the supersonic flow pattern remained symmetric too. However, at high subcritical operating conditions, an asymmetric supersonic flow pattern was observed at both 0 deg angle of attack and sideslip angle. Moreover, an asymmetric pressure ratio distribution inside both diffusers, left and right, were observed. This asymmetric flow behavior in a perfectly symmetric Y-shaped DSI inlet seems to have not been noticed by the previous researchers, but if it has, the result has not been published yet. The performance curve of the current DSI presented at both symmetric and asymmetric flow patterns reveal a significant reduction in its performance characteristics at high subcritical operating conditions that is believed to be caused by the asymmetric flow patterns. In addition, symmetric and asymmetric secondary normal shock- wave patterns were further observed during both supercritical and high subcritical operating conditions. It is observed that the flow asymmetry in this inlet happened when the inlet exit area had blocked more than 50% of the aerodynamic interface plane.

Design and analysis of a Ventral Diverterless Supersonic Inlet

The diverterless supersonic inlet (DSI) has the advantages of good stealth performance and light structure weight. In this paper, the Bump surface is designed based on the flow field obtained by Taylor-Maccoll equation solving the supersonic conical flow, and a ventral diverterless supersonic inlet is given by the method. Numerical simulation is used to study the mechanism of the Bump surface for diverting the boundary layer. Results indicates: (1) the lateral pressure gradient created by the shock wave at the leading edge of the Bump surface is the main reason of pushing the boundary layer away; (2) the total pressure loss due to the shock wave will be small for better combination of the Bump surface and the lip; (3) it is necessary to design the duct of the DSI inlet with refinement to achieve low distortion.

Design and optimization of bump (compression surface) for diverterless supersonic inlet

In this article design and optimization scheme of a three-dimensional bump surface for a supersonic aircraft is presented. A baseline bump and inlet duct with forward cowl lip is initially modeled in accordance with an existing bump configuration on a supersonic jet aircraft. Various design parameters for bump surface of diverterless supersonic inlet systems are identified, and design space is established using sensitivity analysis to identify the uncertainty associated with each design parameter by the one-factor-at-a-time approach. Subsequently, the designed configurations are selected by performing a three-level design of experiments using the Box–Behnken method and the numerical simulations. Surrogate modeling is carried out by the least square regression method to identify the fitness function, and optimization is performed using genetic algorithm based on pressure recovery as the objective function. The resultant optimized bump configuration demonstrates significant improvement in pressure recovery and flow characteristics as compared to baseline configuration at both supersonic and subsonic flow conditions and at design and off-design conditions. The proposed design and optimization methodology can be applied for optimizing the bump surface design of any diverterless supersonic inlet system for maximizing the intake performance.

Flow Asymmetry in a Y-Shaped Diverterless Supersonic Inlet: A Novel Finding

Extensive wind-tunnel tests were performed on a Y-shaped diverterless supersonic inlet (DSI). All tests were conducted at a free stream Mach number of , the design Mach number for this inlet, and at both zero degrees angle of attack (AOA) and angle of sideslip (AOS). The experiments were performed at various inlet operating conditions comprising supercritical, critical, and subcritical conditions that covered almost all ranges of the engine operating for this DSI. The results showed that the DSI had relatively acceptable performance characteristics when operating at its design condition. A symmetric supersonic flow pattern was observed at both supercritical and critical operating conditions of the present Y-shaped DSI. However, both symmetric and asymmetric supersonic flow patterns were observed during the subcritical operating conditions of the present inlet. At low subcritical operating conditions, the supersonic flow pattern remained symmetric, similar to that of the critical operating condition case. As the inlet experienced higher subcritical operating conditions, the supersonic flow structures became suddenly asymmetric and a new flow pattern was noticed. This flow pattern was seen to be highly unstable; and significant asymmetric shock wave oscillations, boundary-layer thickening, and shock-/boundary-layer interaction were observed for these situations. To the authors’ knowledge, this novel phenomenon of asymmetric flow behavior in a perfectly manufactured symmetric Y-shaped DSI encountering symmetric flow (0 deg AOA and AOS) has not been noticed by previous researchers and, if so, the results have not been published yet.

Angle of Attack Investigations on the Performance of a Diverterless Supersonic Inlet

An extensive experimental investigation to study the effects of angle of attack (AOA) on the performance of a body-integrated supersonic inlet has been carried out. The present inlet, known as Diverterless Supersonic Inlet (DSI), is utilized with a three-dimensional bump to provide both supersonic flow compression and boundary layer diversion. Experiments were conducted at the presence of a typical fore-body including an elliptical nose to further contemplate the effects of fore-body geometry on the approaching flow. All tests were conducted at a constant free stream Mach number, M_∞=1.65 zero degrees angle of sideslip (AOS), and at various angles of attack (AOA) ranging from -2 to 6 degrees. The results showed that the present DSI had acceptable performance characteristics for all ranges of AOA tested. It should be noted that the present DSI does not have any moving, adjustable or auxiliary mechanisms as such systems or mechanism are used to improve the performance of an inlet.

Design and performance study of a parametric diverterless supersonic inlet

Diverterless supersonic inlet integration for a flight vehicle requires a three-dimensional compression surface (bump) design with an acceptable shock structure and boundary layer diversion; this results in a low drag induction system with acceptable propulsive efficiency. In this investigation, a computational fluid dynamics-based-generated bump is used to design an integrated diverterless supersonic inlet without any bleed mechanism on a forebody with a large wetted area. Numerical solution of the Navier–Stokes equations simulates the flow pattern of the configuration. The forebody design analysis includes simulating the effects of angle of attack and sideslip by dependent computational domains. Results demonstrate the ability of the bump surface to keep the shock structures in an operational mode even at high supersonic angles of attack. Analysis of shock structures and shock wave boundary layer interactions at supersonic maneuver conditions indicate that the aerodynamic efficiency of the diverterless supersonic inlet in conditions with a thick boundary layer and high angles of attack is sufficient to ensure operation throughout the supersonic flight envelope.

Effects of Mach Number on the Performance of a Diverterless Supersonic Inlet

Extensive experiments were conducted on a body-integrated diverterless supersonic inlet (DSI). Diverterless supersonic inlets are designed and developed in order to provide both supersonic flow compression and boundary-layer diversion by using a three-dimensional bump in combination with a suitable cowl lip. The present experiments were performed at three different freestream Mach numbers of , 1.65 (the design Mach number), and 1.85, as well as at 0 deg angles of attack and angles of sideslip. To model the performance accurately, the intake was integrated with a typical forebody including a nose with an elliptical cross section. Wind-tunnel tests were conducted at critical, subcritical, and supercritical operating conditions. The results showed that the present DSI has acceptable performance in these operating conditions and is able to provide the required mass flow and static pressure ratios. For all conditions examined in this study, as a significant result, the fixed geometry of the designed DSI showed acceptable performance in the ranges of supersonic Mach numbers tested: ; furthermore, its operation in the subsonic condition of was satisfactory. It should be mentioned that there were no movable parts or an auxiliary flow control system for this intake.

On the performance of a body integrated diverterless supersonic inlet

Extensive experimental investigations on a body integrated Diverterless Supersonic Inlet (DSI) were conducted. These inlets are implemented for both supersonic flow compression and boundary layer diversion using a three-dimensional bump in combination with a suitable cowl lip. Experiments were performed at a free stream Mach number of 1.65, the design Mach number, and at zero degrees angle of attack and zero degrees sideslip angle. To recreate the operational conditions more accurately and have a realistic performance characteristic, the intake was integrated with a fuselage and a forebody nose with an elliptical cross-section. Wind tunnel tests were conducted at critical, subcritical and supercritical operating conditions where DSI operates in its stable states. The results showed that the present DSI had acceptable performance characteristics in the stable operating conditions and provides the required mass flow and static pressure compression ratio. In addition, it has a wide stable subcritical operating condition. Moreover, a relatively different behavior in the DSI performance curve is evident due to its body integrated geometry and 3D configuration of the bump and cowl lip, especially in the supercritical conditions.

Effective optimization on Bump inlet using meta-model multi-objective particle swarm assisted by expected hyper-volume improvement

This paper presents an efficient multi-objective optimization method, focusing on aerodynamic optimization of a diverterless supersonic inlet (DSI) in transonic and supersonic flight conditions. The DSI inlet, through scrutinizing the Bump shape has potential to attain greater aerodynamic performance on exit plane of inlet. However, the high cost of computational fluid dynamic (CFD) simulations raises a significant challenge in the DSI optimization process. In order to obtain solution set in few numbers of objective function calls, a meta-model multi-objective particle swarm optimization (MOPSO) method is proposed based on a self-adaptive Kriging surrogate model, and applied to solve this kind of costly black-box optimization problem. The Kriging model is updated by using a dynamic expected hyper-volume improvement (EHVI) sample metric, which is developed by analyzing disadvantages of the original sample criterion. With the help of the dynamic sample metric, simulation results show that the surrogate-based MOPSO algorithm can obtain plenty enough non-dominated solutions and achieve high precision in the approximation of the Pareto front. In terms of DSI inlet optimization, the bump shape is parameterized by free form deformation (FFD) method, and the total pressure distortions of inlet exit plane are treated as two minimization objectives under transonic and supersonic flight conditions. A well distributed non-dominated solution set is generated by the proposed algorithm within the context of a small call number of cost evaluations, and optimized inlet configurated by the selected solution has better aerodynamic characteristics compared with the initial inlet.

Flow field and performance analysis of an integrated diverterless supersonic inlet

AbstractIn this paper the computed flow and performance characteristics at low angle-of-attack (AOA) of an integrated diverterless supersonic inlet (DSI) are presented. The subsonic characteristics are evaluated at M∞ = 0·8 while the supersonic characteristics are evaluated at M∞= 1·7, which is near the design Mach number for the intake. In addition to the external flow features, the internal intake duct flow behaviour is also evaluated. The results of this study indicate effective boundary layer diversion due to the ‘bump’ compression surface in both subsonic and supersonic regimes. At M∞ = 1·7, the shockwave structure (oblique/normal shockwave) on the ‘bump’ compression surface and intake inlet is satisfactory at design (critical) mass flow rate. The intake duct flow behaviour at subsonic and supersonic conditions is generally consistent with ‘Y’ shaped intake duct of the present configuration. The secondary flow structure inside the duct has been effectively captured by present computations. The computed intake total pressure recovery at M∞ = 1·7 exhibits higher-than-conventional behaviour at low mass flow ratios, which is attributed to unique inlet design. Overall computed subsonic and supersonic total pressure recovery characteristics are satisfactory under the evaluated conditions and are also in agreement with wind tunnel test data.