This might help:

IF object_id('TempDB..#Temp') IS NOT NULL

DROP TABLE #Temp

CREATE TABLE #Temp (DateTimeRow DATETIME)

DECLARE @STARTDATE DATETIME, @StartTimeChar CHAR(5), @EndTimeChar CHAR(5);

SELECT

@STARTDATE = CAST(GETDATE() AS DATE),

@StartTimeChar = '08:00', -- note left-padded digit

@EndTimeChar = '10:00';

-- inline tally table CTE

WITH E1(N) AS (

SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL

SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL

SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1), -- 10 rows

E2(N) AS (SELECT 1 FROM E1 a, E1 b),-- 10*10 = 100 rows

iTally(N) AS (SELECT 1 FROM E2 a, E2 b)-- 100*100 = 10000 rows max

INSERT INTO #Temp

(DateTimeRow)

SELECT TOP(1+DATEDIFF(minute,@StartTimeChar,@EndTimeChar)/15) -- number of rows to collect

DateTimeRow = DATEADD(minute,((ROW_NUMBER() OVER(ORDER BY (SELECT NULL))-1)*15),StartDateTime)

FROM iTally -- row source - inline tally table

CROSS APPLY (

SELECT StartDateTime =

DATEADD(hour,CAST(LEFT(@StartTimeChar,2) AS INT),@STARTDATE)

) x;

SELECT * FROM #Temp;