Investigation of cowl vent slots for stability enhancement in MITS scramjet inlets

White, Michael E.; Stevens, J. R.; Wie, David Van; Mattes, L.; Keirsey, James L.

doi:10.2514/6.1988-2956

Cited by 2 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An extensive inlet performance data base was obtained providing the information required to make performance tradeoffs necessary for choosing an optimum inlet configuration. 2 For all configurations tested, the cowl vent slots provided a significant improvement in the measured supercritical inlet stability. In general, the effectiveness of the cowl vent slots for improving supercritical inlet stability was enhanced as the inlet module was operated at more leeward angles of attack.…”

Section: Discussionmentioning

confidence: 95%

“…I). 2 The first test series was conducted at Mach 4 to demonstrate the feasibility of using cowl vent slots for supercritical stability enhancement with an inlet model designed such that the forebody shock-on-lip condition was at a freestream Mach number of 6. The internal compression field was designed to be isentropic and focused at a point inside the inlet innerbody at a freestream Mach number of 4.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of cowl vent slots for supercritical stability enhancement in dual-mode ramjet inlets

White

Stevens

Wie

et al. 1990

Journal of Propulsion and Power

View full text Add to dashboard Cite

T HE supercritical stability margin of inward-turning scoop inlets applicable to dual-mode ramjet engines has been greatly enhanced by the incorporation of a series of cowl vent slots just downstream of the inlet throat. Data has been obtained over a range of Mach number, angle of attack, and roll angle, using two single-module inlet models. A data base has been established to characterize the effect of varying available slot spill area on the stable operating range of the inlet and on the maximum inlet air capture and pressure recovery. IntroductionA particularly attractive cycle for hypersonic air-breathing propulsion systems is the dual-mode ramjet, which operates in a subsonic combustion mode at low supersonic Mach numbers and transitions smoothly to a supersonic combustion mode of operation as the flight Mach number increases. An experimental program has been completed in which the performance of cowl vent slots for use in improving the supercritical stability margin in dual-mode ramjet inlets was demonstrated. Tests have been conducted between Mach 3 and 6 using two singlescoop inlet models consistent with a multiple inward-turning scoop (MITS) inlet concept.The MITS inlet concept incorporates four "scramjet" scoops, located around a vehicle periphery, each of which captures a portion of the required engine airflow and compresses the captured air by turning it inward toward the vehicle centerline. Furthermore, the internal inlet ducting wraps the flow captured by the four scoops such that at the combustor exit a completely annular stream is delivered. These inlets are designed to operate in a dual mode in that the internal ducting downstream of the inlet throat also serves as an isolator duct for stabilization of the inlet precombustion shock system. 1 The performance payoff possible with the use of controlled inlet bypass becomes especially beneficial for a dual-mode engine operating with a multimodule inlet feeding a common combustor. When the vehicle is operating at angle of attack the leeward modules are in a less favorable flowfield and are operating at a significantly reduced performance level. Typically, the maximum thrust level attainable corresponds to the

show abstract

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Investigation of cowl vent slots for supercritical stability enhancement in dual-mode ramjet inlets

White

Stevens

Wie

et al. 1990

Journal of Propulsion and Power

View full text Add to dashboard Cite

show abstract

“…Some (White et al, 1988) refer to dual-mode as a scramjet which can operate both in ramjet and scramjet modes at separate times and make the transition between the two modes via either a change in geometry, inflow conditions and/or fuelling rates and locations. Whereas other types (Vinogradov et al, 1990) incorporate two combustion chambers where combustion occurs subsonically in one and supersonically in the other.…”

Section: Introductionmentioning

confidence: 99%

Investigation of pre-combustion shock trains in a sramjet using a shock tunnel at Mach 8 flight conditions

Ridings¹

View full text Add to dashboard Cite

One of the major challenges to scramjet propulsion is the ability to operate over a wide range of Mach numbers. The dual-mode scramjet has the advantage that it can operate much like a ramjet at low Mach numbers, with subsonic flow entering the combustion chamber, and as a conventional scramjet at higher Mach numbers where the flow remains supersonic throughout the engine. A dual-mode scramjet is able to operate as a ramjet by allowing a shock train to form in the section between the inlet and combustor known as the isolator. This pre-combustion shock train, which is a series of intersecting shock and expansion waves, provides additional compression of the flow allowing subsonic flow to be supplied to the combustion chamber.Free-piston shock tunnels, such as Stalker Tubes, are typically used to test scramjet engines due to the high enthalpy flows which these facilities can produce. However these impulse type wind tunnels have short test times of the order of milliseconds. As the pre-combustion shock train involves large regions of separated flow, which take longer than attached flow to establish, there is some question as to whether dual mode can be modelled in Stalker Tubes.This work investigates whether pre-combustion shock trains can be studied in shock tunnels at the upper end of the dual-mode regime and if so, how this phenomenon affects scramjet performance. Experiments were conducted in the T4 Stalker Tube at The University of Queensland at a condition which represents flight at Mach 8 at an altitude of 26 km. This corresponds to a dynamic pressure of 105 kPa and a total enthalpy of 3.1 MJ kg −1 .The experiments were conducted using a simple axi-symmetric scramjet, which comprised a short inlet, an isolator, fuel injectors and three interchangeable combustion chambers. The set of combustion chambers consisted of a constant area and two divergent combustors with half-cone angles of 1 • and 2 • . The different combustion chambers were tested to assess the effect which area expansion has on the shock train and on the overall combustion efficiency of the engine. The model was arranged in a semi-direct connect configuration to produce the desired conditions at the isolator entrance. Gaseous hydrogen was used as the fuel and was injected via six port-hole injectors equally spaced around the circumference. Wall static pressures were measured along the isolator and combustor walls. A quasi-one-dimensional cycle analysis code, ii which is capable of modelling separated flow, is used to model the flow through the engine and provides estimates of the combustion efficiency and distribution of heat release.Robust combustion was observed in the experiments over a range of fuel equivalence ratios between 0.5 and 1.35, for all three combustor configurations. Results for the constant area combustor show that at an equivalence ratio approximately equal to 0.7 the boundary layer separates due to the pressure rise generated from combustion, forming a shock train upstream of fuel injection. With increasing equivalence...

show abstract

Investigation of cowl vent slots for stability enhancement in MITS scramjet inlets

Cited by 2 publications

References 0 publications

Investigation of cowl vent slots for supercritical stability enhancement in dual-mode ramjet inlets

Investigation of cowl vent slots for supercritical stability enhancement in dual-mode ramjet inlets

Investigation of pre-combustion shock trains in a sramjet using a shock tunnel at Mach 8 flight conditions

Contact Info

Product

Resources

About