Underexpanded jet

Underlying Flow Regime 1-01 © copyright ERCOFTAC 2004

Quality Review

'Underlying Flow Regime Title': The under-expanded jet

UFR Author and UFR number: Dr J Kidger, HSL, UFR 1-01

'Reviewer (Name/Organisation) : Prof. Dr.-Ing. 'M. Sommerfeld, MLU-Halle

1	TOP LEVEL CHECK	YES	NO	CO
1. 1	Is the selected test-case study a good representation of the assigned UFR?	n	q	q
1. 2	Does the test-case study include both flow measurements and CFD calculations?	n	q	q
1. 3	Does the document under review comply with the D32 template	n	q	q
1. 4	Should any parts be expanded, condensed or deleted?	q	n	q
1. 5	Are the illustrations and their captions clear and informative?	n	q	q
1. 6	Are the references adequate and complete?	n	q	q
1. 7	If any hyperlinks are used, do these function correctly?	n	q	q

Comments:

DETAILED CHECK

2	REVIEW OF UFR STUDIES AND CHOICE OF TEST CASE	YES	NO	CO
2. 1	Have past studies of the UFR been reviewed adequately?	q	q	n
2. 2	Is the chosen test-case study selected from an established database or comparison exercise?	q	n	q
2. 3	Have the test-case experiments been devised for CFD validation?	n	q	q

Comments:
2.1 I dont know, but I hope

3	DESCRIPTION OF THE STUDY TEST CASE	YES	NO	CO
3. 1	Is the geometry described adequately, including an appropriate sketch?	q	q	n
3. 2	Are the flow parameters defining the flow regime specified?	n	q	q
3. 3	Are the principal measured quantities (i.e. those by which success or failure of CFD is to be judged) specified?	n	q	q
3. 4	Is the description fully self-contained and sufficiently detailed ? (the level of detail required depends on whether a hyperlink to a detailed database is provided)	n	q	q

Comments:
3.1 More geometrical details of the converging-diverging nozzle should to be provided,
e.g. length of diverging part, angle of divergence, geometry of the through.

Comment by UFR author: Geometrical details of the shape of the converging-diverging nozzle used by Seiner & Norum (1979,1980) are not referenced. However the authors state they used design guidelines (unreferenced) and a method of characteristics to ensure that the flow was parallel and supersonic at the stated Mach number at the nozzle exit. The situation is similar for the converging nozzle used by Donaldson & Snedecker (1971). There is no reason to suspect that the nozzles were not well designed and gave the stated performance. This being the case, CFD simulations can be undertaken without geometrical details of the upstream part of these nozzles: The domain boundary can be coincident with the nozzle exit. Because the flow is choked at the nozzle exit, no information from the downstream computation can propagate upstream into the nozzle.

4	Test CASE EXPERIMENTS	YES	NO	CO
4. 1	Is the test-case facility described adequately?	n	q	q
4. 2	Are the measurement techniques explained?	n	q	q
4. 3	Is the quality/accuracy of the measured data discussed?	n	q	q
4. 4	Are the following quality aspects addressed in this discussion :-			n
a)	Closeness of flow to target/design conditions?	q	q	q
b)	Accuracy estimation of measured quantities?	q	q	q
c)	Checks on global conservation of conserved quantities?	q	q	q
d)	Consistency in the measurements of different quantities?	q	q	q
e)	Other (briefly describe)			q
4. 5	Is the evidence of data quality judged to be sufficient?	n	q	q
4. 6	Is the information provided at the flow boundaries sufficient to specify or estimate reasonably well the boundary conditions required for a CFD calculation?	n	q	q
4. 7	Is the overall discussion self-contained and sufficiently detailed? (the level of detail required depends on whether a hyperlink to a detailed database is provided)	n	q	q

Comments:
4.4 This information was not provided in the respective references.

5	CFD METHODS	YES	NO	CO
5. 1	Is an overview given of the methods used?	n	q	q
5. 2	Have the following aspects of the methods used been explained adequately:-
a)	The codes employed?	n	q	q
b)	The turbulence/physical models used?	n	q	q
c)	The wall treatments applied?	n	q	q
d)	The numerical boundary conditions?	n	q	q
5. 3	Are comments made on how well the boundary conditions replicate conditions in the test rig?	n	q	q
5. 4	Is the quality of the calculations discussed?	n	q	q
5. 5	Are the following quality aspects addressed in this discussion?			q
a)	The discretisation scheme(s) and solver(s)?	n	q	q
b)	The sufficiency of grid resolution(s) ?	n	q	q
c)	Sensitivities to uncertainties in the boundary conditions	n	q	q
d)	Comparisons between separate calculations using the same physical model	q	q	n
e)	Other (briefly describe)			q
5. 6	Is the evidence of CFD quality judged to be sufficient in all cases?	n	q	q

Comments:
5.5 d) such information was not available in the associated references

6	COMPARISON OF CFD CALCULATIONS WITH EXPERIMENT	YES	NO	CO
6. 1	Are key comparisons of CFD results with experiment presented in the form of tables or plots?	n	q	q
6. 2	Do these comparisons include the assessment quantities?	n	q	q
6. 3	Are further comparisons available via hyperlinks to a results database?	q	n	q
6. 4	Is the performance of the CFD calculations judged by comparison with experiments discussed and analysed in all cases?	n	q	q

Comments:

7	BEST PRACTICE ADVICE FOR THE UFR	YES	NO	CO
7. 1	Are model abilities for this test case discussed and analysed in sufficient detail?	n	q	q
7. 2	Are recommendations provided on which models should be used for this UFR?	n	q	q
7. 3	Are these recommendations supported by the evidence?	n	q	q

Comments: