Performance of a Turbine Driven by a Pulsed Detonation Combustor

2011 ◽  
Author(s):  
Kurt P. Rouser ◽  
Paul I. King ◽  
Frederick R. Schauer ◽  
Rolf Sondergaard ◽  
John L. Hoke
Keyword(s):  
Reverse Flow ◽  
Specific Work ◽  
Time Resolved ◽  
Performance Variables ◽  
Pulsed Detonation ◽  
Fill Fraction ◽  
Pressure Gain Combustion ◽  
Time Histories ◽  
Exit Temperature ◽  
Integrated Performance

There is longstanding government and industry interest in pressure-gain combustion for use in Brayton cycle-based engines. Theoretically, pressure-gain combustion allows heat addition with reduced entropy loss. The pulsed detonation combustor (PDC) is a device that can provide such pressure-gain combustion and possibly replace the typical steady deflagration combustor. The PDC is inherently unsteady, however, and comparisons with steady deflagration combustors must be based upon time-integrated performance variables. In this study, the radial turbine of a Garrett automotive turbocharger was coupled directly to and driven, full admission, by a hydrogen-fueled PDC fueled. Data included pulsed-cycle time histories of turbine inlet and exit temperature, pressure, velocity, mass flow, and enthalpy. The unsteady inlet flowfield showed momentary reverse flow, and thus unsteady accumulation and expulsion of mass and enthalpy within the device. The coupled turbine-driven compressor provided a time-resolved measure of turbine power. Duty cycle increased with PDC frequency. Power and cycle-average specific work increased with PDC frequency and fill fraction.

Performance Evaluation of an Unsteady Turbine Driven by a Pulsed Detonation Combustor

2011 ◽  
Author(s):  
Kurt P. Rouser ◽  
Paul I. King ◽  
Frederick R. Schauer ◽  
Rolf Sondergaard ◽  
John L. Hoke
Keyword(s):  
Reverse Flow ◽  
Brayton Cycle ◽  
Rotor Speed ◽  
Performance Improvements ◽  
Pulsed Detonation ◽  
Time Histories ◽  
Exit Temperature ◽  
Shaft Torque ◽  
Low Entropy ◽  
Gas Pressures

Replacing a Brayton cycle near constant-pressure combustor with a pulsed detonation combustor (PDC) may take advantage of potential performance improvements from low-entropy, pressure-gain heat addition. In this paper, the radial turbine of a Garrett automotive turbocharger is coupled to a hydrogen fueled PDC. Unsteady turbine power is obtained with a conventional dynamometer technique. Sampling frequencies greater than 10 kHz resolve rapid flowfield transients of confined detonations which occur in less than a millisecond and include peak gas pressures exceeding 4 MPa and peak gas temperatures greater than 2,400 K. Results include 6 ms time histories of turbine inlet and exit temperature, pressure, mass flow, and enthalpy during blowdown of a PDC. The unsteady inlet flowfield included momentary reverse flow, which was not observed at the turbine exit. Full pulsed detonation cycle time histories of turbine power, rotor speed, rotational energy and net shaft torque are included to describe the turbine response to detonations. Rotor speed is periodic and net shaft torque oscillates in response to a detonation. Results are shown for fill fractions ranging from 0.5 to 1.0 with a 0.5 purge fraction. PDC operating frequencies in this study range from 10 Hz to 25 Hz.

Pressure Gain Combustion Application to Marine and Industrial Gas Turbines

2012 ◽  
Author(s):  
Philip H. Snyder ◽  
M. Razi Nalim
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Technology Development ◽  
Innovative Technology ◽  
Turbine Engines ◽  
Specific Work ◽  
Compression Pressure ◽  
Pressure Gain Combustion ◽  
Industrial Gas Turbines ◽  
Incremental Improvement

Renewed interest in pressure gain combustion applied as a replacement of conventional combustors within gas turbine engines creates the potential for greatly increased capability engines in the marine power market segment. A limited analysis has been conducted to estimate the degree of improvements possible in engine thermal efficiency and specific work for a type of wave rotor device utilizing these principles. The analysis considers a realistic level of component losses. The features of this innovative technology are compared with those of more common incremental improvement types of technology for the purpose of assessing potentials for initial market entry within the marine gas turbine market. Both recuperation and non-recuperation cycles are analyzed. Specific fuel consumption improvements in excess of 35% over those of a Brayton cycle are indicated. The technology exhibits the greatest percentage potential in improving efficiency for engines utilizing relatively low or moderate mechanical compression pressure ratios. Specific work increases are indicated to be of an equally dramatic magnitude. The advantages of the pressure gain combustion approach are reviewed as well as its technology development status.

scholarly journals Intake Flow Analysis of a Pulsed Detonation Engine

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Joshua A. Strafaccia ◽  
Semih M. Ölçmen ◽  
John L. Hoke ◽  
Daniel E. Paxson
Keyword(s):  
Fluid Dynamic ◽  
Flow Analysis ◽  
Engine Performance ◽  
Fuel Injector ◽  
Pulse Detonation ◽  
Pulsed Detonation Engine ◽  
Pulsed Detonation ◽  
Fill Fraction ◽  
Detonation Engine ◽  
Intake Flow

Unsteady flow within the intake system of a hydrogen–air pulse detonation engine (PDE) has been analyzed using a quasi-one-dimensional (Q1D) computational fluid dynamic (CFD) code. The analysis provides insight into the unsteady nature of localized equivalence ratios and their effects on PDE performance. For this purpose, a code originally configured to model the PDE tube proper was modified to include a 6.1 m long intake with a single fuel injector located approximately 3.05 m upstream of the primary intake valve. The results show that constant fuel mass flow rate injection from the injector creates large local variations in equivalence ratio throughout the PDE within a cycle. The effect of fill fraction on the engine performance is better described with the presence of the inlet model. However, the effect of ignition delay is shown to be better predicted with a model without the inlet.

Experimental Validation of the Addition Principle for Pulsating Flow in Close-Coupled Catalyst Manifolds

2006 ◽  
Vol 128 (4) ◽  
pp. 656-670 ◽  
Author(s):  
Tim Persoons ◽  
Ad Hoefnagels ◽  
Eric Van den Bulck
Keyword(s):  
Experimental Validation ◽  
Engine Speed ◽  
Reverse Flow ◽  
Pulsating Flow ◽  
Exhaust Manifold ◽  
Flow Uniformity ◽  
Blow Down ◽  
Time Resolved ◽  
Flow Through ◽  
Good Agreement

Designing an exhaust manifold with close-coupled catalyst (CCC) relies heavily on time-consuming transient computional fluid dynamics. The current paper provides experimental validation of the addition principle for pulsating flow in CCC manifolds. The addition principle states that the time-averaged catalyst velocity distribution in pulsating flow equals a linear combination of velocity distributions obtained for steady flow through each of the exhaust runners. A charged motored engine flow rig provides cold pulsating flow in the exhaust manifold featuring blow down and displacement phases, typical of fired engine conditions. Oscillating hot-wire anemometry is used to measure the bidirectional velocity, with a maximum measurable negative velocity of −1m∕s. In part load and zero load conditions, instantaneous reverse flow occurs following the blow-down phase. The two-stage nature of the exhaust stroke combined with strong Helmholtz resonances results in strong fluctuations of the time-resolved mean catalyst velocity. The validity of the addition principle is quantified based on the shape and magnitude similarity between steady and pulsating flow distributions. Appropriate nondimensional groups are used to characterize the flow and quantify the similarity. Statistical significances are provided for the addition principle’s validity. The addition principle is valid when the nondimensional scavenging number S exceeds a critical value Scrit, corresponding to cases of low engine speed and/or high flow rate. This study suggests that the CCC manifold efficiency with respect to catalyst flow uniformity could be quantified using a single scalar parameter, i.e., Scrit. The results from the current study are discussed with respect to previously reported results. The combined results are in good agreement and provide a thorough statistically founded experimental validation of the addition principle, based on a broad applicability range.

Experimental and Analytical Surge Cycle Analysis of a High Pressure Aero Engine Compressor

2012 ◽  
Author(s):  
Phillip Waniczek ◽  
Harald Schoenenborn ◽  
Peter Jeschke
Keyword(s):  
Flow Field ◽  
Reverse Flow ◽  
Flow Direction ◽  
Specific Work ◽  
Rotor Speed ◽  
Suction Surface ◽  
Trailing Edge ◽  
Wide Range ◽  
Aero Engine ◽  
Engine Compressor

The unsteady flow field during surge of the front rotor of an eight-stage axial aero engine compressor has been investigated experimentally and analytically. For that purpose, two newly designed multi-sensor probes are installed up- and downstream of the first rotor. Surge experiments are conducted at four different speed lines (75–93% speed) covering a wide range of the compressor map and measurements have been taken at two different channel heights (50% and 70% span). The results show that the flow field varies extremely during surge up- and downstream of the rotor. In contrast to the flow at the rotor leading edge, which is nearly independent of the rotor speed, the flow at the rotor trailing edge is highly dependent of the rotor speed. Therefore, the performance of the rotor during surge is dependent on the reverse through-flow of the stators. At low speeds the flow passes the stators without any changes in the flow direction. If speed is increased the reverse flow is guided more and more by the stators. These different flow conditions have a direct impact on the process of energy conversion of the rotor during the surge event. The incoming reverse flow at the rotor trailing edge impinges on the blade from the suction surface side at lower speeds and turns to the pressure surface side when speed is increased. Hence, the deviation and specific work grow. In addition to the surge experiments simulations of the surge events are conducted with a 1D code called SYSQ3D. The simulations and experiments match well and underline the capability of the new multi-sensor probes to accurately measure the flow patterns during surge.

Flow Field Investigation in a Low-Solidity Inducer by Laser-Doppler Velocimetry

1990 ◽  
Vol 112 (1) ◽  
pp. 91-97 ◽  
Author(s):  
A. Boccazzi ◽  
A. Perdichizzi ◽  
U. Tabacco
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Reverse Flow ◽  
Field Investigation ◽  
Design Flow ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Pressure Probe ◽  
Specific Work ◽  
Flow Angle

The results of an experimental investigation of the flow field within a low-solidity inducer at design and off-design flow rates are presented and discussed; particular attention is devoted to the analysis of the flow field, at the tip in front of the leading edge, for the flow rate close to the back-flow onset. The flow field was measured by means of a laser-Doppler velocimeter at four different axial positions upstream, within, and downstream of the inducer. Axial, tangential, and relative flow angle distributions, in the measuring planes, are presented for three different flow coefficients. At the lower flow rate, the plots show the presence of reverse flow in the region close to the hub downstream of the trailing edge. For the same flow rate, quite low axial velocities are detected at the tip. This is in agreement with pressure probe traverses carried out in a slightly downstream section; these measurements also show radial inward velocities of the same order of magnitude as the axial velocities. Circumferentially averaged losses were evaluated from specific work and total head rise given by pressure probes.

Influence of the Arrangement of Dilution Holes for Dilution Mixing in a Three-Injector Reverse Flow Combustor

2014 ◽  
Author(s):  
Wei Dai ◽  
Yan Zhang ◽  
Yuzhen Lin ◽  
Qian Yang ◽  
Chi Zhang
Keyword(s):  
Temperature Profile ◽  
Swirling Flow ◽  
Reverse Flow ◽  
Ambient Pressure ◽  
Outer Ring ◽  
Inlet Temperature ◽  
Test Model ◽  
Mixing Rate ◽  
Mixing Performance ◽  
Exit Temperature

The exit temperature profile has a great effect on the reliability and security in a gas turbine. In this paper, the exit temperature profile of a small engine reverse-flow combustor with three injectors test module was experimentally obtained to qualitatively analyze the influence of the dilution hole distribution. The test model was a three-injector rectangular reverse-flow combustor with swirling flow atomizing. A 1D moving thermocouple rake was used to measure the global exit temperature profile of the combustor. The pressure was at ambient pressure with the inlet temperature was 290K. The FAR was in the range of 0.03. The dilution holes were in opposed and staggered arrangements. The experimental results showed that the exit temperature profile was obviously influenced by the dilution holes. Compared with the opposed dilution jets, the staggered dilution jets provided more uniform circumferential exit temperature profile, but a little higher pattern factor of 0.1725. The numerical results showed that the staggered dilution jets generated a larger scale counter-rotating vortex pairs. The inner and outer jets not only did not interact with each other (especially at the outer ring of combustor), but also filled the intermediate regions of dilution jets, resulting in a higher gas mixing rate. Consequently, the staggered dilution jets provided a better mixing performance for the outer ring of combustor.

scholarly journals Turbulent separation upstream of a forward-facing step

2013 ◽  
Vol 724 ◽  
pp. 284-304 ◽  
Author(s):  
D. S. Pearson ◽  
P. J. Goulart ◽  
B. Ganapathisubramani
Keyword(s):  
Boundary Layer ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Steady Increase ◽  
Separation Region ◽  
Two Dimensional ◽  
Low Velocity ◽  
Time Resolved ◽  
Displacement Thickness ◽  
Forward Facing Step

AbstractThe turbulent flow over a forward-facing step is studied using two-dimensional time-resolved particle image velocimetry. The structure and behaviour of the separation region in front of the step is investigated using conditional averages based on the area of reverse flow present. The relation between the position of the upstream separation and the two-dimensional shape of the separation region is presented. It is shown that when of ‘closed’ form, the separation region can become unstable resulting in the ejection of fluid over the corner of the step. The separation region is shown to grow simultaneously in both the wall-normal and streamwise directions, to a point where the maximum extent of the upstream position of separation is limited by the accompanying transfer of mass over the step corner. The conditional averages are traced backwards in time to identify the average behaviour of the boundary-layer displacement thickness leading up to such events. It is shown that these ejections are preceded by the convection of low-velocity regions from upstream, resulting in a three-dimensional interaction within the separation region. The size of the low-velocity regions, and the time scale at which the separation region fluctuates, is shown to be consistent with the large boundary layer structures observed in the literature. Instances of a highly suppressed separation region are accompanied by a steady increase in velocity in the upstream boundary layer.

An Integrated Performance Modeling System

2004 ◽  
Author(s):  
David Kazmer ◽  
Liang Zhu
Keyword(s):  
Quality Control ◽  
Performance Modeling ◽  
Specification Limits ◽  
Performance Variables ◽  
Historical View ◽  
Decision Variables ◽  
Current Value ◽  
Integrated Performance ◽  
Control Limits ◽  
Function Matrix

An integrated performance modeling system is presented for use in general decision making problems including engineering design, manufacturing process and quality control, and other applications. The system relies on a function matrix that relates decision variables to performance variables. The system utilizes both global and local linearization of non-linear functions, after which the Extensive Simplex Method is used to derive the set of all feasible decisions based upon the specification limits for the performance variables and the control limits on the decision variables. Beyond current Six Sigma best practices, the described system explicitly considers both modeling uncertainty and uncontrolled variation. The specification limits may be automatically tightened by the confidence intervals and variation limits to ensure feasibility to a desired level of confidence and robustness. Three sets of feasible decisions are established including 1) the global feasible set that establishes the extreme limits of feasibility by allowing all the decision variables to vary simultaneously within their range of the control limits, 2) the local feasibility, which shows the immediate feasibility for each decision variable holding other decision variables at their current value, and 3) the controllable feasibility for each performance variable holding other performance variables at their current value. The system provides a perspective view of 1) the function matrix, 2) a historical view of the decision variables which may be used in a manner similar to statistical process control X-Bar charts, 3) a historical view of the performance variables which may be used in a manner similar to statistical quality control charts, 4) a set of decision windows showing the joint feasibility of all pairs of decision variables, which may be used in a manner similar to process windows, and 5) a set of performance windows showing the joint feasibility of all pairs of performance variables, which may be used in a manner similar to Pareto Optimal graphs. An example is provided for a beam design model with four decision variables and three performance variables.

scholarly journals Potentials for Pressure Gain Combustion in Advanced Gas Turbine Cycles

2019 ◽  
Vol 9 (16) ◽  
pp. 3211
Author(s):  
Nicolai Neumann ◽  
Dieter Peitsch
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Specific Work ◽  
Turbine Cooling ◽  
Turbine Efficiency ◽  
Optimization Study ◽  
Pressure Gain Combustion ◽  
Reduce Emissions ◽  
Secondary Air ◽  
Gas Turbine Cycle

Pressure gain combustion evokes great interest as it promises to increase significantly gas turbine efficiency and reduce emissions. This also applies to advanced thermodynamic cycles with heat exchangers for intercooling and recuperation. These cycles are superior to the classic Brayton cycle and deliver higher specific work and/or thermal efficiency. The combination of this revolutionary type of combustion in an intercooled or recuperated gas turbine cycle can, however, lead to even higher efficiency or specific work. The research of these potentials is the topic of the presented paper. For that purpose, different gas turbine setups for intercooling, recuperation, and combined intercooling and recuperation are modeled in a gas turbine performance code. A secondary air system for turbine cooling is incorporated, as well as a blade temperature evaluation. The pressure gain combustion is represented by analytical-algebraic and empirical models from the literature. Key gas turbine specifications are then subject to a comprehensive optimization study, in order to identify the design with the highest thermal efficiency. The results indicate that the combination of intercooling and pressure gain combustion creates synergies. The thermal efficiency is increased by 10 percentage points compared to a conventional gas turbine with isobaric combustion.

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